Ascertainment and Prevention of Genetic Disease

A genetic register system has been developed for the ascertainment and prevention of genetic disease. Its potential value is illustrated with data collected from 478 families with serious genetic disorders which had been seen during the past five years. Of these 249 were referred specifically for genetic counselling, autosomal dominant disorders accounting for the largest group of families with individuals at high risk of becoming affected. Of 717 individuals at high risk of having affected children (or carrier daughters in the case of X-linked recessive disorders), only 101 were referred specifically for counselling. Many were referred only after the birth of an affected child which might otherwise have been prevented. A genetic register system linked to practitioner, hospital, and health department records could be a valuable means of preventing genetic disease.     

Prospective study of genetic counselling.

A prospective study was carried out on 200 consecutive subjects seen for counselling (consultands) for serious genetic disorders. Educational and social background of consultands and their knowledge and understanding of their particular problem were assessed before counselling, and their response was determined immediately afterwards and three months and two years later by an independent observer not concerned in the genetic counselling. The husband''s educational background was particularly important in influencing a couple''s comprehension of counselling. X-linked recessive and chromosomal disorders presented the most difficulties in comprehension. The counsellors'' assessment of comprehension was a good guide to the consultands'' comprehension as assessed at subsequent follow-up. The proportion deterred from having children increased with time and over a third had been sterilised within two years of counselling. It is suggested that follow-up after counselling should be routine, especially when the counsellor suspects that comprehension has not been good, in X-linked recessive and chromosomal disorders, and when the risks of having an affected child are considered to be high.     

Learning to Eat Vegetables in Early Life: The Role of Timing,Age and Individual Eating Traits

Vegetable intake is generally low among children, who appear to be especially fussy during the pre-school years. Repeated exposure is known to enhance intake of a novel vegetable in early life but individual differences in response to familiarisation have emerged from recent studies. In order to understand the factors which predict different responses to repeated exposure, data from the same experiment conducted in three groups of children from three countries (n = 332) aged 4–38 m (18.9±9.9 m) were combined and modelled. During the intervention period each child was given between 5 and 10 exposures to a novel vegetable (artichoke puree) in one of three versions (basic, sweet or added energy). Intake of basic artichoke puree was measured both before and after the exposure period. Overall, younger children consumed more artichoke than older children. Four distinct patterns of eating behaviour during the exposure period were defined. Most children were “learners” (40%) who increased intake over time. 21% consumed more than 75% of what was offered each time and were labelled “plate-clearers”. 16% were considered “non-eaters” eating less than 10 g by the 5^th exposure and the remainder were classified as “others” (23%) since their pattern was highly variable. Age was a significant predictor of eating pattern, with older pre-school children more likely to be non-eaters. Plate-clearers had higher enjoyment of food and lower satiety responsiveness than non-eaters who scored highest on food fussiness. Children in the added energy condition showed the smallest change in intake over time, compared to those in the basic or sweetened artichoke condition. Clearly whilst repeated exposure familiarises children with a novel food, alternative strategies that focus on encouraging initial tastes of the target food might be needed for the fussier and older pre-school children.     

THE CHALLENGE OF THE “WELL CHILD”

Upon general practitioners and pediatricians falls the responsibility of recognizing and treating most emotional problems in young children. This may be best carried out by the anticipation of expected problems, and the advance guidance or counseling of parents. That such problems are of high incidence was indicated in experience at a pediatric clinic where approximately 40 per cent of 7,000 children observed had psychosomatic symptoms.In order to utilize effectively the limited time available in office practice for Well Child care, a physician must have at hand certain basic information on personality development. Many of the normal behavior patterns in children which frequently are misinterpreted as “behavior problems” by parents are presented herein in chart form, divided into critical age periods, to help physicians quickly recognize what is normal and what abnormal in various periods of maximal crisis. Most of the problems of conflict within a child and of conflict between parents and child, it is felt, could be and should be handled at the pediatric level. Some seriously disturbed children need to be referred for psychiatric care. When this is necessary, skillful preparation of the parent and the child by the family physician for referral is most important to successful psychotherapy.     

Association between Mouth Breathing and Atopic Dermatitis in Japanese Children 2–6 years Old: A Population-Based Cross-Sectional Study

As mouth breathing is associated with asthma and otitis media, it may be associated with other diseases. Therefore, this population-based cross-sectional study evaluated the association of mouth breathing with the prevalences of various diseases in children. Preschool children older than 2 years were included. A questionnaire was given to parents/guardians at 13 nurseries in Tokushima City. There were 468 valid responses (45.2%). We defined a subject as a mouth breather in daytime (MBD) if they had 2 or more positive items among the 3 following items: “breathes with mouth ordinarily,” “mouth is open ordinarily,” and “mouth is open when chewing.” We defined subjects as mouth breathers during sleep (MBS) if they had 2 or more positive items among the following 3 items: “snoring,” “mouth is open during sleeping,” and “mouth is dry when your child gets up.” The prevalences of MBD and MBS were 35.5% and 45.9%, respectively. There were significant associations between MBD and atopic dermatitis (odds ratio [OR]: 2.4, 95% confidence interval [CI]: 1.4–4.2), MBS and atopic dermatitis (OR: 2.4, 95% CI: 1.3–4.2), and MBD and asthma (OR: 2.2, 95% CI: 1.2–4.0). After adjusting for history of asthma and allergic rhinitis; family history of atopic dermatitis, asthma, and allergic rhinitis; and nasal congestion; both MBD (OR: 2.6, 95% CI: 1.3–5.4) and MBS (OR: 4.1, 95% CI: 1.8–9.2) were significantly associated with atopic dermatitis. In preschool children older than 2 years, both MBD and MBS may be associated with the onset or development of atopic dermatitis.     

Genetic counseling in carriers of reciprocal translocations involving two autosomes

One of the main genetic causes involve in the pathogenesis of recurrent abortion is parental chromosomal abnormalities. The central concept in genetic counseling with such families is to estimate the probability of recurrence of unfavorable pregnancy outcomes. The main questions that consultants usually ask are: Why did this happen? What is the risk to be done again?Our cases were two families with repeated miscarriage. The pedigrees were drawn, the chromosomes of couples were studied, and estimation for recurrent risk was done. We tried to answer those two main questions and clear the results for them.Parental chromosome abnormalities were founded after karyotyping with GTG technique at 450 band resolution, revealing 46 chromosomes with balanced translocation of autosomes in one of the partner in both families. Recurrent risk was estimated as “high” for their future pregnancies in each family.Couples in which one partner is the carrier of such balanced translocation have increased risks of infertility, recurrent abortion, and delivery of chromosomally abnormal offspring. Genetic counseling of such couples, therefore, presents a unique challenge and should be considered in dealing with such families.     

Preventive Psychiatry: The Psychiatric Team as Consultant to the Public Health Nurse

Various forms of collaboration between the disciplines of public health and psychiatry are briefly reviewed and the 25-year-old mental health program of the Vancouver Health Department is described. The public health nurse has prime responsibility in all children with emotional disorders. She is supported by a psychiatric team which provides active treatment and educational and consultative help for the nurse and the school. During the year 1963, six social workers had 2357 contacts with nurses and school personnel but only 1049 treatment interviews. Of 401 children referred to the psychiatric team, 138 received active clinic treatment, 141 remained under supervision by the public health nurse, and 122 were referred elsewhere. In addition, 1330 children were identified as “mental hygiene cases” in the caseload of the 170 public health nurses in the community. By close co-ordination, the public health nurse and the psychiatric team can enhance each other''s contributions to community mental health.     

Laboratory policies and practices for the genetic testing of children: a survey of the Helix network.

In order to discover whether laboratories have policies regarding the testing of unaffected children, we surveyed all laboratories registered with Helix, a national net-work of DNA diagnostic laboratories. Of 186 laboratories asked to respond anonymously to a four-page questionnaire, 156 (84%) replied. A screening question removed 51 laboratories that provided no clinical services. Of the remaining 105, 92% said that their requisition forms asked the person's age. Substantial minorities had policies for the testing of minors for late-onset disorders (46%), for carrier status for recessive disorders (33%), or for disorders for which the test offers no medical benefit within 3 years (33%). Most laboratories are responsive to parental requests. For 12 of 13 late-onset disorders, the majority of laboratories that offered testing had had requests to test children. The majority had tested healthy children, <12 years of age, for eight disorders. Approximately 22% had tested children, <12 years of age, for Huntington disease. Majorities had received requests to test healthy children for carrier status for 10 of 15 recessive or X-linked disorders and had tested children, <12 years of age, for 6 of these disorders, including cystic fibrosis, hemophilia A, fragile X syndrome, and Duchenne muscular dystrophy. Approximately 45% of the laboratories occasionally had provided tests directly to consumers. In view of the possibility that the harms of presymptomatic diagnoses of children sometimes may outweigh the benefits, our results suggest a need for consistent laboratory policies designed for the best interests of the child and the family.     

Genetic risks for children of women with myotonic dystrophy

In genetic counseling, the recommended risk estimate that any heterozygous woman with myotonic dystrophy (DM) will have a congenitally affected child is 3%-9%. However, after already having had such an offspring, a DM mother's risk increases to 20%-37%. The risks of 10% and 41%, respectively, calculated in this study are similar to the estimates in the literature. However, our data on clinical status of the mothers demonstrate that only women with multisystem effects of the disorder at the time of pregnancy and delivery are likely to have congenitally affected offspring. No heterozygous woman with polychromatic lens changes but no other clinically detectable multisystem involvement had a congenitally affected child. In addition, our data suggest that the chance of having a more severely affected child increases with greater severity of maternal disease. The findings of this study are relevant for genetic counseling, as the risk of having a congenitally affected child for women with classical manifestations of the disease is shown to be higher than predicted by the overall risk estimate for any heterozygous woman. We consider it appropriate to give these classically affected women risk figures which approach the recurrence risk given to mothers with congenitally affected children. However, the risk of having a congenitally affected child for heterozygous women with no multisystem involvement appears to be minimal. Our findings support the earlier proposed hypothesis of maternal metabolites acting on a heterozygous offspring. Neither genomic imprinting nor mitochondrial inheritance is able to explain the correlation between the clinical status of heterozygous mothers and that of their children.     

Familial risk of oral clefts by morphological type and severity: population based cohort study of first degree relatives

Objective To estimate the relative risk of recurrence of oral cleft in first degree relatives in relation to cleft morphology.Design Population based cohort study.Setting Data from the medical birth registry of Norway linked with clinical data on virtually all cleft patients treated in Norway over a 35 year period.Participants 2.1 million children born in Norway between 1967 and 2001, 4138 of whom were treated for an oral cleft.Main outcome measure Relative risk of recurrence of isolated clefts from parent to child and between full siblings, for anatomic subgroups of clefts.Results Among first degree relatives, the relative risk of recurrence of cleft was 32 (95% confidence interval 24.6 to 40.3) for any cleft lip and 56 (37.2 to 84.8) for cleft palate only (P difference=0.02). The risk of clefts among children of affected mothers and affected fathers was similar. Risks of recurrence were also similar for parent-offspring and sibling-sibling pairs. The “crossover” risk between any cleft lip and cleft palate only was 3.0 (1.3 to 6.7). The severity of the primary case was unrelated to the risk of recurrence.Conclusions The stronger family recurrence of cleft palate only suggests a larger genetic component for cleft palate only than for any cleft lip. The weaker risk of crossover between the two types of cleft indicates relatively distinct causes. The similarity of mother-offspring, father-offspring, and sibling-sibling risks is consistent with genetic risk that works chiefly through fetal genes. Anatomical severity does not affect the recurrence risk in first degree relatives, which argues against a multifactorial threshold model of causation.     

The Risks of Sleeping “Too Much”. Survey of a National Representative Sample of 24671 Adults (INPES Health Barometer)

Background

A significant U-shaped association between sleep duration and several morbidity (obesity, diabetes or cardiovascular disease) and mortality risks has been regularly reported. However, although the physiological pathways and risks associated with “too short sleep” (<5 hours/day) have been well demonstrated, little is known about “too much sleeping”.

Purpose

To explore socio-demographic characteristics and comorbidities of “long sleepers” (over 10 hours/day) from a nationally representative sample of adults.

Methods

A cross-sectional nationally representative sample of 24,671 subjects from 15 to 85-year-old. An estimated total sleep time (TST) on non-leisure days was calculated based on a specifically designed sleep log which allows to distinguish “long sleepers” from “short sleepers” (<5 hours/day). Insomnia was assessed according to the International classification of sleep disorders (ICSD-2).

Results

The average TST was 7 hours and 13 minutes (+/− 17 minutes). Six hundred and twelve subjects were “long sleepers” (2.7%) and 1969 “short sleepers” (7.5%). Compared to the whole group, “long sleepers” were more often female, younger (15–25 year-old) or older (above 65 year-old), with no academic degree, mostly clerks and blue collar workers. “Long sleepers” were significantly more likely to have psychiatric diseases and a greater body mass index (BMI). However, long sleep was not significantly associated with the presence of any other chronic medical disease assessed. Conversely, short sleep duration was significantly associated with almost all the other chronic diseases assessed.

Conclusions

In the general population, sleeping too much was associated with psychiatric diseases and higher BMI, but not with other chronic medical diseases.     

The Clinical Significance of the Biological False Positive Serologic Reactor: A Study of 113 Cases

Biological false positive serologic reactors were studied during a long-term follow-up of asymptomatic patients with chronic false positive serology for syphilitic reagin. This was done with a view to facilitating the early diagnosis of systemic disease, particularly collagen disorders, which are frequently associated with this finding in women. One hundred and thirteen cases were studied. Thirty-eight were “acute”, i.e. positive for less than six months, 58 were “chronic”, i.e. positive for more than six months, and the remainder still positive but followed for less than six months. Of 39 female chronic reactors, 10 were diagnosed as having collagen disease, and in six the BFP reaction preceded clinical diagnosis of the disease. Five had no apparent disease. In 19 male chronic reactors, there was no evidence of collagen disorders and five were free of any recognizable pathology. The remainder in both sexes were found to have a wide variety of systemic illnesses.     

The Working Capacity of Subjects from an Exhibition Crowd

A standard bicycle ergometer test was performed on 60 male volunteers at the Canadian National Exhibition. Most were drawn from Toronto and its environs, and “white-collar” workers predominated. Ages ranged from 19 to 61 years. The Astrand nomogram was used to predict the oxygen uptake of the 45 subjects with a normal resting pulse rate. The older subjects had a lower oxygen uptake than Scandinavian office workers, particularly relative to body weight. This conclusion is subject to the limitations of a non-random sample, but seems independent of the professional-class bias. Almost all subjects exceeded the “ideal” body weight. Working capacity was 20% greater in subjects taking regular exercise than in those who were inactive.     

Prenatal genetic screening and the evolving quest for “perfect babies”: at what cost for genetic diversity?

Commercial screening services for inheritable diseases raise concerns about pressure on parents to terminate “imperfect babies”. Subject Categories: S&S: Economics & Business, Molecular Biology of Disease

Nearly two decades have passed since the first draft sequences of the human genome were published at the eyewatering cost of nearly US$3 billion for the publicly funded project. Sequencing costs have dropped drastically since, and a range of direct‐to‐consumer genetics companies now offer partial sequencing of your individual genome in the US$100 price range, and whole‐genome sequencing for less than US$1,000.While such tests are mainly for personal peruse, there have also been substantial drops in price in clinical genome sequencing, which has greatly enabled the study of and screening for inheritable disorders. This has both advanced our understanding of these diseases in general, and benefitted early diagnosis of many genetic disorders, which is crucial for early and efficient treatment. Such detection can, in fact, now occur long before birth: from cell‐free DNA testing during the first trimester of pregnancy, to genetic testing of embryos generated by in vitro fertilization, to preconception carrier screening of parents to find out if both are carriers of an autosomal recessive condition. While such prenatal testing of foetuses or embryos primarily focuses on diseases caused by chromosomal abnormalities, technological advances allow also for the testing of an increasing number of heritable monogenic conditions in cases where the disease‐causing variants are known.The medical benefits of such screening are obvious: I personally have lost two pregnancies, one to Turner''s syndrome and the other to an extremely rare and lethal autosomal recessive skeletal dysplasia, and I know first‐hand the heartbreak and devastation involved in finding out that you will lose the child you already love so much. It should be noted though that, very rarely, Turner syndrome is survivable and the long‐term outlook is typically good in those cases (GARD, 2021). In addition, I have Kallmann syndrome, a highly genetically complex dominant endocrine disorder (Maoine et al, 2018), and early detection and treatment make a difference in outcome. Being able to screen early during pregnancy or childhood therefore has significant benefits for affected children. Many other genetic disorders similarly benefit from prenatal screening and detection.But there is also obvious cause for concern: the concept of “designer babies” selected for sex, physical features, or other apparent benefits is well entrenched in our society – and indeed culture – as a product from a dystopian future. Just as a recent example, Philipp Ball, writing for the Guardian in 2017, described designer babies as “an ethical horror waiting to happen” (Ball, 2017). In addition, various commercial enterprises hope to capitalize on these screening technologies. Orchid Inc claims that their preconception screening allows you to “… safely and naturally, protect your baby from diseases that run in your family”. The fact that this is hugely problematic if not impossible from a technological perspective has already been extensively clarified by Lior Pachter, a computational biologist at Caltech (Pachter, 2021). George Church at Harvard University suggested creating a DNA‐based dating app that would effectively prevent people who are both carriers for certain genetic conditions from matching (Flynn, 2019). Richard Dawkins at Oxford University recently commented that “…the decision to deliberately give birth to a Down [syndrome] baby, when you have the choice to abort it early in the pregnancy, might actually be immoral from the point of view of the child’s own welfare” (Dawkins, 2021).These are just a few examples, and as screening technology becomes cheaper, more companies will jump on the bandwagon of perfect “healthy” babies. Conversely, this creates a risk that parents come under pressure to terminate pregnancies with “imperfect babies” as I have experienced myself. What does this mean for people with rare diseases? From my personal moral perspective, the ethics are clear in cases where the pregnancy is clearly not viable. Yet, there are literally thousands of monogenic conditions and even chromosomal abnormalities, not all of which are lethal, and we are making constant strides in treating conditions that were previously considered untreatable. In addition, there is still societal prejudice against people with genetic disorders, and ignorance about how it is to live with a rare disease. In reality, however, all rare disease patients I have encountered are happy to be alive and here, even those whose conditions have significant impact on their quality of life. Many of us also don''t like the term “disorder” or “syndrome”, as we are so much more than merely a disorder or a syndrome.Unfortunately, I also see many parents panic about the results of prenatal testing. Without adequate genetic counselling, they do not understand that their baby’s condition may have actually a quite good prognosis without major impact on the quality of life. Following from this, a mere diagnosis of a rare disease – many of which would not even necessarily have been detectable until later in life, if at all – can be enough to make parents consider termination, due to social stigma.This of course raises the thorny issue of regulation, which range from the USA where there is little to no regulation of such screening technologies (ACOG, 2020), to Sweden where such screening technologies are banned with the exception of specific high‐risk/lethal medical conditions both parents are known carriers for (SMER, 2021). As countries come to grips with both the potential and the risks involved in new screening technologies, medical ethics board have approached this issue. And as screening technologies advance, we will need to ask ourselves difficult questions as a society. I know that in the world of “perfect babies” that some of these companies and individuals are trying to promote, I would not exist, nor would my daughter. I have never before had to find myself so often explaining to people that our lives have value, and I do not want to continue having to do so. Like other forms of diversity, genetic diversity is important and makes us richer as a society. As these screening technologies quickly advance and become more widely available, regulation should at least guarantee that screening must involve proper genetic counselling from a trained clinical geneticist so that parents actually understand the implications of the test results. More urgently, we need to address the problem of societal attitudes towards rare diseases, face the prejudice and fear towards patients, and understand that abolishing genetic diversity in a quest for perfect babies would impoverish humanity and make the world a much poorer place.     

Psychological Aspects of Cystic Fibrosis in Children and Adolescents

Medical care of children with cystic fibrosis has been so greatly improved in recent years that many are now reaching adolescence and early adulthood. Traversing adolescence is a trying task for any chronically ill child, but even more difficult for the cystic fibrosis patient. Clinicians report that many of these adolescents have problems for which the patients, the family, and the practitioners need help. The key to dealing with the problems is to attempt to approach “normality” of living as closely as possible as early as possible despite the risks inherent.     

Effect of Measles Vaccination on Incidence of Measles in the Community

A study of the effect of measles vaccination on the incidence of the disease in eight separate areas of England and Wales was begun in 1966. It showed an inverse association between the proportion of children vaccinated and the incidence of measles in the area in the following year, but measles epidemics occurred in several of the areas in subsequent years, despite continuing vaccinations.Measles vaccination was introduced on a large scale in Britain in 1968. Analysis of the notification and vaccination statistics shows that the vaccination of about 10% of the child population (under 15 years) in 1968 sufficed to “replace” the measles epidemic which had been expected in the period October 1968 to September 1969 by a low incidence of the disease, typical of that in previous “interepidemic” years. Further, the effect of the vaccinations was to prevent the development of natural measles in susceptible unvaccinated children as well as in the vaccinated subjects. Thus the number of immune subjects in the community was increased by the vaccinations, but as a result there was a reduction in the number of subjects who acquired immunity from natural measles. These opposed results can therefore explain why vaccination may be effective in the community for only a year or two, though vaccination protects the individual for much longer.It is estimated that a continuing vaccination rate of 40 to 50% of the children born each year would be necessary to replace the regular biennial measles epidemics in Britain by a continuous endemic incidence, and might perhaps lead to the disappearance of the disease without a further major epidemic, but that a continuing vaccination rate of 80 to 90% of children born each year would then be necessary to prevent its reintroduction. The long-term control of measles by vaccination will thus probably prove more difficult than for any other infectious disease.     

Clients'' interpretation of risks provided in genetic counseling.

Clients in 544 genetic counseling sessions who were given numeric risks of having a child with a birth defect between 0% and 50% were asked to interpret these numeric risks on a five-point scale, ranging from very low to very high. Whereas clients' modal interpretation varied directly with numeric risks between 0% and 15%, the modal category of client risk interpretation remained "moderate" at risks between 15% and 50%. Uncertainty about normalcy of the next child increased as numeric risk increased, and few clients were willing to indicate that the child would probably or definitely be affected regardless of the numeric risk. Characteristics associated with clients' "pessimistic" interpretations of risk, identified by stepwise linear regression, included increased numeric risk, discussion in depth during the counseling session of whether they would have a child, have a living affected child, discussion of the effects of an affected child on relationships with client's other children, and seriousness of the disorder in question (causes intellectual impairment). Client interpretations are discussed in terms of recent developments in cognitive theory, including heuristics that influence judgments about risks, and implications for genetic counseling.     

Do Maternal Knowledge and Attitudes towards Childhood Immunizations in Rural Uganda Correlate with Complete Childhood Vaccination?

Improving childhood vaccination coverage and timeliness is a key health policy objective in many developing countries such as Uganda. Of the many factors known to influence uptake of childhood immunizations in under resourced settings, parents’ understanding and perception of childhood immunizations has largely been overlooked. The aims of this study were to survey mothers’ knowledge and attitudes towards childhood immunizations and then determine if these variables correlate with the timely vaccination coverage of their children. From September to December 2013, we conducted a cross-sectional survey of 1,000 parous women in rural Sheema district in southwest Uganda. The survey collected socio-demographic data and knowledge and attitudes towards childhood immunizations. For the women with at least one child between the age of one month and five years who also had a vaccination card available for the child (N = 302), the vaccination status of this child was assessed. 88% of these children received age-appropriate, on-time immunizations. 93.5% of the women were able to state that childhood immunizations protect children from diseases. The women not able to point this out were significantly more likely to have an under-vaccinated child (PR 1.354: 95% CI 1.018–1.802). When asked why vaccination rates may be low in their community, the two most common responses were “fearful of side effects” and “ignorance/disinterest/laziness” (44% each). The factors influencing caregivers’ demand for childhood immunizations vary widely between, and also within, developing countries. Research that elucidates local knowledge and attitudes, like this study, allows for decisions and policy pertaining to vaccination programs to be more effective at improving child vaccination rates.     

Color Discrimination in the Tufted Capuchin Monkey,Sapajus spp

The present study evaluated the efficacy of an adapted version of the Mollon-Reffin test for the behavioral investigation of color vision in capuchin monkeys. Ten tufted capuchin monkeys (Sapajus spp., formerly referred to as Cebus apella) had their DNA analyzed and were characterized as the following: one trichromat female, seven deuteranope dichromats (six males and one female), and two protanope males, one of which was identified as an “ML protanope.” For their behavioral characterization, all of the subjects were tested at three regions of the Commission International de l''Eclairage (CIE) 1976 u′v′ diagram, with each test consisting of 20 chromatic variation vectors that were radially distributed around the chromaticity point set as the test background. The phenotypes inferred from the behavioral data were in complete agreement with those predicted from the genetic analysis, with the threshold distribution clearly differentiating between trichromats and dichromats and the estimated confusion lines characteristically converging for deuteranopes and the “classic” protanope. The discrimination pattern of the ML protanope was intermediate between protan and deutan, with confusion lines horizontally oriented and parallel to each other. The observed phenotypic differentiation confirmed the efficacy of the Mollon-Reffin test paradigm as a useful tool for evaluating color discrimination in nonhuman primates. Especially noteworthy was the demonstration of behavioral segregation between the “classic” and “ML” protanopes, suggesting identifiable behavioral consequences of even slight variations in the spectral sensitivity of M/L photopigments in dichromats.