Frequencies of centromeric heteromorphisms of human chromosomes 3 and 4 as detected by QFQ technique: can they be identified by RFA technique?

One hundred normal Caucasians were studied by sequential QFQ and RFA banding techniques in order to estimate the type and frequency of heteromorphisms in the centromeric regions of chromosome 3 and 4. Intensity variants were classified into 1 of 5 levels of QFQ banding. QFQ intensity heteromorphisms (greater than or equal to level 3) for chromosomes 3 and 4 were 62 and 15 percent respectively. The interrelationship between QFQ and RFA variants were also examined. When the centromere was brilliant by QFQ, it was found that it was deep red by RFA; when it was pale by QFQ, it was light red by RFA. Neverthless, a blind coded study could not pick up these color variants by RFA. QFQ banding showed variations of the centromeric regions of chromosomes 3 and 4 while RFA banding failed to demonstrate it. It was concluded that QFQ is the most useful technique in detecting the different intensity levels in the centromeric regions of chromsomes 3 and 4.     

A cytogenetic survey of an institution for the mentally retarded

Summary Heteromorphisms of chromosomes 1,9, and 16 were studied by C-banding in a population of 403 mentally retarded individuals from diverse ethinic groups. A significant difference in the distribution of heteromorphisms was found among the different racial groups. The Orientals had a larger C-band on chromosome 1 and a smaller C-band on chromosome 9 than the other racial groups while the Caucasians had a larger C-band on chromosome 9. The Oriental group also had a significantly greater proportion of inverted C-band. No differences were found in the distribution of C-band heteromorphisms among different etiologic categories of mental retardation.     

Expression of nucleolus organizer regions (NORs) in human acrocentric chromosomes by NSG, QFQ and RFA techniques: are they identical?

The morphology of nucleolus organizer regions (NORs) of human acrocentric chromosomes has been studied in a family by QFQ, RFA, and NSG banding techniques. The pale green colour seen by RFA was found darkly stained by NSG. However, in some instances, NOR regions were expressed by NSG technique but the pale green colour was not seen. Therefore, it is concluded that there is no direct relationship between a heteromorphism identified by one technique and that identified by another.     

Human chromosomal heteromorphisms in Delhi newborns. II. Analysis of C-band size heteromorphisms in chromosomes 1, 9 and 16

Quantitative analysis of C-band size heteromorphisms in chromosomes 1,9 and 16 was carried out in 200 Delhi newborns (100 males and 100 females). The percent size heteromorphisms for chromosomes 1,9 and 16 showed nonsignificant differences between the sexes. Homozygous size level combinations showed higher incidence than the heterozygous combinations for all the three chromosome pairs studied in both sexes. Our results are compared with other reported studies and the possible role of these heteromorphisms in ethnic/racial variation and in developmental disturbances is discussed.     

Population heteromorphisms of Ag-stained nucleolus organizer regions (NORs) in the acrocentric chromosomes of East Indians

Summary The nucleolar organizer regions (NORs) of acrocentric chromosomes in 70 normal East Indians were examined by Ag-staining (NSG) and acridine orange reverse banding (RFA) techniques. The Ag-stainability of NORs was variable from one individual to another but characteristics were constant within each individual. The average modal number of Agpositive NORs per individual was eight. A racial difference in the expression of NORs is suggested. to study the heteromorphism of NORs, the NSG technique was found to be more useful than RFA. Furthermore, it is concluded that there is no direct relationship between a heteromorphism of NORs identified by NSG and that identified by the RFA technique. Quantitative data on these differences is provided. In addition NOR-regions are classified into five sizes namely; very large, large, medium, small, and very small using subjectively defined criteria.     

Y-chromosome length heteromorphisms in Delhi infants

One hundred and seventy normal male infants from Delhi were studied using the CBG technique to estimate Y-chromosome length heteromorphisms. The median class in Y/F [Y/F = total length of the Y chromosome/average total length of the F group chromosomes (19 and 20)] distribution was 0.75-0.79. The Y/F index in infants varied from 0.60 to 1.16 with a mean of 0.81 and a standard deviation of 0.09. A high incidence for very small (53.5 percent) and small (41.2 percent) categories of Y-chromosome length heteromorphisms was observed. Data were compared with other available reports; also possible mechanisms of the Y-chromosome length heteromorphisms and their role in ethnic/racial variation as well as in developmental disturbances are discussed. It is suggested there may be a need to redefine the long and short Y chromosome in a given population while studying different clinical disorders.     

Chromosomal heteromorphisms in Delhi infants. III. Qualitative analysis of C-band inversion heteromorphisms of chromosomes 1, 9, and 16

Qualitative analysis of C-band heteromorphisms was carried out in 200 infants (100 males and 100 females) in Delhi, India. Partial inversions minor and half inversions were observed as modal levels for chromosomes 1 and 9 in both sexes. No chromosome 16 with a C-band inversion was observed in the present investigation. A significantly higher incidence of percent inversions for chromosomes 1 and 9 was observed in males than in females. The frequency of heterozygous inversion level combinations for chromosome pairs 1 and 9 were remarkably higher than homozygous combinations both in males and females. Our results are compared with the other reported studies, and the possible role of these heteromorphisms in ethnic/racial variation and in developmental disturbances are discussed.     

Equivalence of the total constitutive heterochromatin content by an interchromosomal compensation in the C band sizes of chromosomes 1, 9, 16, and Y in Caucasian and Japanese individuals

A quantitative analysis of C bands by densitometric measurements in chromosomes 1, 9, 16, and Y was conducted in Caucasians and Japanese living in Brazil. Sixty normal unrelated subjects (30 males and 30 females) were studied in each racial group. Caucasians presented C bands of chromosomes 1, 9, and 16 larger than Japanese, but, on average, only the difference for C bands of chromosome 9 was statistically significant. In the Japanese, the C band sizes of chromosomes Y were, on average, significantly larger than in the Caucasians. The mean C band size of chromosome 9 and the sum of the three pairs were significantly larger in Caucasian than in Japanese males. The total values of constitutive heterochromatin, sigma (1qh,9qh,16qh,Yq12), did not show significant difference between Caucasian and Japanese males. The relative C band sizes of chromosomes 1, 9, and 16 were, on average, similar in Caucasians and Japanese. No sex difference was found in both racial groups. As regards the heteromorphism, only the values of C bands of chromosome 9 were, on average, significantly larger in Caucasians than in Japanese. Partial inversions were detected only among the Caucasians.     

Skeletal muscle characteristics in sedentary black and Caucasian males

Twenty-three male Black African and 23 male Caucasian subjects, ascertained as sedentary, participated in this study designed to determine whether there were differences in skeletal muscle histochemical and biochemical characteristics between racial groups. Muscle fiber type proportions (I, IIa, and IIb), fiber areas and activities of several enzyme markers of different energy metabolic pathways were determined from a biopsy of the vastus lateralis. Results indicated that Caucasians had a higher percent type I (8%, P less than 0.01) and a lower percent type IIa (6.7%, P less than 0.05) fiber proportions than Africans. No significant differences were observed between the two racial groups in the type IIb fiber proportion or in the three fiber type areas. Enzymes catalyzing reactions in phosphagenic [creatine kinase (CK)] and glycolytic [hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH)] metabolic pathways had significantly higher activities (about 30-40%) in the Black African group than in the Caucasian group (P less than 0.01). No significant difference was noted in the activities of oxidative enzymes [malate dehydrogenase (MDH), oxoglutarate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA dehydrogenase (HADH)]. Consequently, the PFK/OGDH ratio was significantly elevated in Africans (P less than 0.05). The racial differences observed between Africans and Caucasians in fiber type proportion and enzyme activities of the phosphagenic and glycolytic metabolic pathways may well result from inherited variation. These data suggest that sedentary male Black individuals are, in terms of skeletal muscle characteristics, well endowed for sport events of short duration.     

Mapping the human liver/islet glucose transporter (GLUT2) gene within a genetic linkage map of chromosome 3q using a (CA)n dinucleotide repeat polymorphism and characterization of the polymorphism in three racial groups.

The human liver/islet glucose transporter (GLUT2), a candidate gene for diabetes, has been incorporated into a genetic linkage map for chromosome 3q using a (CA)n dinucleotide repeat polymorphism adjacent to the 3'-end of exon 4a. We have found a total of nine alleles ranging in length from 153 to 169 nucleotides in three racial groups and have determined the precise structure of the variable region for four of the alleles by DNA sequencing. Five alleles were found to be common to the American Black, Caucasian, and Pima Indian racial groups studied. One allele (169 bp) was unique to American Blacks, and another rare allele (153 bp) was found only in the Caucasian population studied. Observed heterozygosity of the polymorphism in the Caucasian (CEPH) reference pedigree collection is 60%, for American Blacks 71%, and for Pima Indians 53%. An independent study recently identified the same dinucleotide repeat and found six alleles in a Caucasian population (Froguel et al., 1991), a result that we confirm; however, our sequencing data indicate a different molecular structure for the polymorphism for some of the alleles. We have constructed a new genetic linkage map of chromosome 3q uniquely placing the GLUT2 gene between flanking markers D3S26 and D3S43. The genetic map consists of 23 loci (25 RFLPs and 2 (CA)n dinucleotide repeat markers) with 14 markers uniquely localized with odds of at least 1000:1. Three genes (FTHL4, TF, GLUT2) are integrated into the map, which spans a sex-average distance of 147.3 cM, 103.8 cM in males and 227.0 cM in females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Co-occurrences of polymorphic heterochromatin regions of chromosomes and effect on reproductive failure

Although the polymorphic heterochromatin regions of chromosomes (heteromorphisms) have been extensively studied for their phenotypic effects on humans, co-occurrences of chromosome 1, 9, 16 and Y heteromorphisms and of acrocentric variants have never been studied on humans with an objective scoring system. Here we compared the frequencies of individual heteromorphisms on a total of 602, 768 and 224 patients with the indications of infertility, recurrent miscarriage and in vitro fertilization (IVF) failure, respectively and on 272 controls. Then we examined whether there were significant co-occurrences between heteromorphisms within and between the groups. There were no statistically significant differences in the frequencies of heteromorphisms between the groups. Both statistically significant and non-significant correlations were observed within the non-acrocentric and certain acrocentric heteromorphisms in each group. When these co-occurrences were examined between the groups, a 2.2 fold increased risk of IVF failure in males in the presence of either chromosome 13 or chromosome 21 variants was observed (95 %CI:1.1–4.2). We conclude that the simultaneous manifestations of heteromorphisms have no effect on reproductive failure. There seems to be a correlation between the non-acrocentric heteromorphisms (1qh+, 9qh+, 16qh + and Yqh+/-), which might be the result of complex interactions of formation of these heterochromatin regions. The correlations observed between certain acrocentric chromosomes might be related to satellite association and nucleolus formation. The increased risk observed in males with IVF failure in the presence of either chromosome 13 or 21 variants should be interpreted cautiously due to the heterogeneity of the group.     

Inversions and other unusual heteromorphisms detected by C-banding

Summary Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied.     

Size variation polymorphisms of the short arm of human acrocentric chromosomes determined by R-banding by fluorescence using acridine orange (RFA)

Summary One hundred normal Caucasians were studied by the RFA technique to estimate the frequencies of size variation of the short arm of acrocentric chromosomes. Each size variation was classified into one of five levels. The most frequent size level (code) was 3; therefore, this was regarded as the average size. If one excludes the average size, the frequencies of size variation by RFA for chromosome 13, 14, 15, 21, and 22 were 22.5, 19.5, 14.5, 19, and 17% respectively. There was no significant difference for the overall frequencies of size variation between sexes. Furthermore, the RFA technique detects more variation in the size of human acrocentric chromosomes than any other method.     

Characterization of glucokinase polymorphisms associated with Maturity-Onset Diabetes of the Young (MODY2) in Jordanian population

Maturity-Onset Diabetes of the Young (MODY) is a monogenic form of Diabetes Mellitus (DM) characterized by an autosomal dominant inheritance, onset usually before 25 years of age and a primary defect in glucose-stimulated insulin secretion, Glucokinase (GCK) acts as a glucose sensor in the pancreatic beta cell and regulates insulin secretion. The mutation in the gene encoding GCK results in enzyme inactivation cause MODY2. Functional studies of naturally occurring GCK mutations associated with hyperglycaemia provide further insight into the biochemical basis of glucose sensor regulation. In this study 100 diabetic Jordanian patients with MODY2 phenotype and 150 Normal control subjects were screened for the presence of GCK gene mutations including the missense mutations at position Thr228Ala in exon 7, Gly299Arg in exon 8 and nonsense mutation Ser383Ter in exon 9, utilizing polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) analysis. The results shows no Thr228Ala, Gly299Arg and Ser383Ter mutations were detected in both groups, which was differ from the results obtained for Italian and Caucasian from the Oxford region in UK MODY2 patients. Our data indicated that the previously studied mutations in Italian and Caucasian patients in the GCK gene are not common in MODY Jordanian population, suggesting a racial difference can be found in the frequency of the GCK polymorphism.     

Glyoxalase I polymorphism and racial admixture in the Cuban population

Summary The polymorphism of glyoxalase I (GLO I) was demonstrated in the three main racial groups (Caucasian, Mulattoes, and Negroes) of the Cuban population. The GLO I gene frequencies were used to estimate the relative contribution of Negro and Caucasian genes to the genetic makeup of these three groups.Banco de Sangre Provincial     

Genogeographic analysis of subdivided population. The Adyge gene pool in the Caucasian gene pool system]

A gene geographic analysis of the indigenous population of the Caucasian historical cultural province was carried out with a set of genetic markers extensively studied in the Adyges (39 alleles of 18 loci): AB0, ACP, C3, FY, GC, GLO, HP, KEL, LEW, MN, MNS, P, PGD, PGM1, RH-C, RH-D, RH-E, and TF. Genetic information on 160 Caucasian populations was used (on average, 65 populations per locus). A synthetic map of the first principal component clearly showed a division into two gene geographic provinces: Northern Caucasus and Transcaucasia. The component significantly differed across the Greater Caucasian Ridge. One of the major regions of extreme values corresponded to the Adyge region. A map of the second component revealed two poles, Northwestern (the Adyges) and Caspian, in gene pool variation of the Caucasian population. The analysis of the maps and the space of principal components showed that the Adyge population is an important component of the Caucasian gene pool. A map of genetic distance from all Caucasian populations to the Adyges showed that the north Caucasian populations (excluding the Ossetes) are the most genetically similar to the Adyges, while Georgians from the Kolkhida Valley and Azerbaijanians from the lowlands near the Caspian Sea and highland steppes are the most genetically remote from the Adyges. The genetic diversity (GST x 10(2)) of the entire Caucasian gene pool was studied. The average diversity of subpopulation within a Caucasian ethnos was GS-E = 0.81, the diversity of ethnoses within a linguistic family was GE-L = 0.83, and the diversity of linguistic families was GL-T = 0.58. The race classification of the Caucasian populations (GS-E = 0.81, GS-R = 0.80, GR-T = 0.76) proved to be more genetically informative than the linguistic one. The major parameters of the Adyges (total diversity HT = 0.364, heterozygosity HS = 0.361, and subpopulation diversity within the ethnos GS-E = 0.69) were similar to those averaged over the entire Caucasian population. A comparison with the same set of genetic markers showed that the interethnic diversity in the Caucasian region was lower than in the other north Eurasian regions (GS-E was 1.24 in the European region, 1.42 in the Ural region, 1.27 in Middle Asia, and 3.85 in Siberia).     

Variation in human acrocentric chromosomes with acridine orange reverse banding.

Twenty-five normal subjects were studied by acridine orange reverse (RFA) banding in order to obtain a preliminary estimate of the type and frequency of variations in color and length. Color variations were classified into 1 of 6 colors and size variations into 1 of 5 levels. The same cells were also studied by Q banding. Acridine orange reverse banding was found to be more useful than Q banding for characterizing variations in chromosomes 14, 15, 21 and 22. In addition, it was found that there was no consistent relationship between pale or bright Q banding and the various colors observed with RFA banding. For the optimal characterization of a chromosomal variation, multiple banding technics, including RFA banding, are necessary.     

Sex differences in lingual marginal ridging on the human maxillary central incisor

Although incisor dimensions are on average larger in males, at least one incisor trait, lingual marginal ridging, is significantly more common in females. This is documented for the upper central incisor in a collation of 38 samples of living populations representing six racial groups. Caucasian, Asian, Polynesian, Melanesian, and American Indian females each possess significantly higher frequencies than their male counterparts. American Blacks do not show a sex difference. Sex differences in the duration and rate of incisor crown development do not explain this dimorphism. Possible underlying genetic causes are reviewed, and the hypothesis is proposed that relevant portions of both X chromosomes in females are contributing to greater trait expression.     

Genetic polymorphism of the erythrocytic enzymes in the Buryat populations

Polymorphism of seven erythrocytic enzymes PGM1, ESD, CLO1, PGD and PGP were studied in five samples of Buryats. The main investment into differentiation between populations has been made by the following systems: CLO1, PGD and PGM1. Analysis of genetic distances between populations demonstrated that there was some parallelism among the genetic and anthropological differentiation in the Buryat populations. The groups of the Agingsky county (the area to the east from the Baikal Lake) have probably the largest proportion of the Caucasian genes as compared to other populations studied. One of the characteristics of the Buryats, especially for the population to the east from the Baikal Lake, is high frequency of the PGD allele. The rate of the genetic variability on the intra-population level is higher than the difference between populations. This means that the divergence between the Buryats populations is not very strong. Consideration of the genetic variability on the intra-population level seems to be more perspective for ecogenetic estimation of the adaptive genetic processes than analysis of the differences between populations studied.     

Risk ratios for obesity in families of obese African-American and Caucasian women

We examined age- and sex-standardized risk ratios (SRRs) in matched samples of 1,185 families of obese African-American and Caucasian women. Familial risk ratios increased with body mass index (BMI) of proband and BMI thresholds of relative. Ratios were higher in Caucasian than African-American families, apparently because Caucasian probands were more extreme relative to their population mean. Risk ratios for moderate obesity (BMI >/= 30) were around 2 for African-Americans and were a little higher in Caucasians. Ratios for extreme obesity (BMI >/= 40) ranged from 3 to 5 in African-Americans and from about 5 to 9 in Caucasians. Thin relatives were rare in families of both races. Risk ratios appear high enough in both racial groups to facilitate the identification of quantitative trait loci underlying common obesity phenotypes. The high population prevalence of obesity in African-American women will require particularly high selection thresholds to achieve risk ratios comparable to those for Caucasians. The scarcity of thin siblings in both groups will greatly increase the effort required in sample recruitment for discordant pair designs.