Analysis of structural and numerical chromosome abnormalities in sperm of normal men and carriers of constitutional chromosome aberrations. A review

Sperm chromosome analysis offers the opportunity to gather information about the origin of chromosome aberrations in human germ cells. Over the last 20 years more than 20 000 sperm chromosome complements from normal donors and almost 6000 spermatozoa from men with constitutional chromosome aberrations (inversions, translocations) have been analyzed for structural and numerical chromosome abnormalities, as well as for segregation of the constitutional chromosome aberrations after the sperm had penetrated hamster oocytes. On the other hand, it took only 6 years to screen more than 3 million mature spermatozoa from healthy probands for disomy rates of 20 autosomes (chromosomes 19 and 22 not evaluated) and the sex chromosomes, and for diploidy rates by in situ hybridization techniques. In the present paper the results arising from both methods are compiled and compared. Received: 29 January 1997 / Accepted: 5 March 1997     

Hypovitaminosis D in a normal, apparently healthy urban European population

Serum 25 OH Vitamin D (25 OH D) concentrations generally vary with latitude, season, and the composition of the population studied. There is a growing recognition that rather than a seasonal specific decline in serum 25 OH Vitamin D, a significant proportion of the population may exhibit asymtomatic subclinical Vitamin D insufficiency. Vitamin D insufficiency has been described in populations at risk, such as nursing home residents and the homebound elderly. We assessed a population of normal, apparently healthy volunteers at a single European urban center for 25 OH Vitamin D sufficiency. Serum 25 OH D concentrations were determined using an automated LIAISON((R)) 25 OH Vitamin D assay. For the purposes of this study, Vitamin D insufficiency was defined as a serum 25 OH Vitamin D concentration of <15 ng/mL. Of the total population (n = 126) 34% exhibited 25 OH Vitamin D concentrations of <15 ng/ml. The mean +/- S.D. serum 25 OH Vitamin D concentration among the total, sufficient, and insufficient populations was 19.4 +/- 7.7, 23.6 +/- 6.4, and 12.1 +/- 2.3 ng/mL. From these data, we conclude that 25 OH Vitamin D insufficiency is more common than previously thought, and is not restricted to high-risk groups.     

Cell selection in vivo in normal/aneuploid chromosome abnormalities

Summary Cytogenetic follow-up examination has been made of the 9 mixoploid children found among 11148 newborn children. In 4 of the 9 children there was a significant increase in the frequency of the cell line with normal chromosome constitution and a significant decrease in the normal cell line was found in 1 child. In 4 there was no significant difference from the first to the last examination.The frequency of the cell line with normal chromosomes increased from 32–68% to between 93–97% in 3 cases and to 86% in 1. The possibility that children with mixoploid chromosome abnormalities at birth will reveal no cell line with chromosome abnormality in lymphocyte cultures as adults in spite of having clinical signs of the chromosome aberration found in one cell line at birth is discussed.     

Genetic analysis of a population with abnormalities of gene frequencies]

Nineteen out of the 53 blood donors of french village with 241 inhabitants (Cezay Loire) are Rh negative (D--). This discrepancy in the distribution is analysed. 1.--The study of the genetic erythrocyte markers (ABO and Rh system for 158 inhabitants, Kell, Rautenberg, Duffy, Kidd, MNSs, P1 Lutheran, PGM1, PGM2, 6 PGD, AK, ADA, Acid phosphatase systems for 104 inhabitants) show significant abnormal gene frequencies (No. 10%) compared with a control population from Saint-Etienne, for A1, Ms, r, P1 alleles; conversely rare alleles do not seem to exist. HLA system was not tested. 2.--The genetic study led to: a) a demographic study which implied 7840 registrar's certificates and the building up of 1364 families to which the 5096 subjects belonged identified and having lived in Cezay since 1607 (this date corresponds to the earliest registrar's certificate). b) it also led to the analysis of the origin and evolution of the genetic inheritance throughout the 13 generations of known inhabitants. The calculation of the chances of each generation having passed on its genetic material to following generations shows that: Cezay has an integrated population; 30% of the genes are renewed for each generation the average value of each founder can vary according to the various generations but there seems to exist a "founder effect" of the Rh--(D--) having been and lived in the village before 1860. Although they represent 68% of the total population, the tested samples can be contested for certain systems, in its constitution (formation, choice) which prevents from ascertaining the foundation effect observed. The authors underligne the contribution of immunogenetics to the genetics of populations, and show the incidence of the choice of samples in the method used.     

Low frequencies of apparently fragile X chromosomes in normal control cultures: a possible explanation

Low frequencies of apparently fragile X [fra(X)] chromosomes have been reported in normal control, short-term, whole blood cultures, and they have been noted in both amniocyte and fetal blood cultures. However, there is currently no universal agreement on the lowest frequency for fra(X)(q27) that is diagnostic for the fragile X syndrome. Here, we present our observations on low levels of apparently fra(X) chromosomes in normal samples. We observed frequencies of 0.5% in short-term whole blood cultures and 0.9% in amniotic fluid cell cultures. In 1982, Steinbach et al. described nonspecific telomeric structural changes (TSC) and suggested that such low frequencies of apparently fra(X) chromosomes in normal material may be occurring by the same mechanism that is responsible for TSC formation. To determine if TSC formation can explain the significant baseline frequencies of fra(X) in normal controls, 10,457 cells were screened from 178 individuals referred for fra(X) analysis. Our findings indicated that TSC are not randomly distributed across chromosomes but tend to occur at specific sites. Based on our observations, we offer the hypothesis that the low frequency of apparent fra(X) in normal individuals may be due to nonrandom TSC distribution.     

Relations of serum interleukin 18 levels to serum lipid and glucose concentrations in an apparently healthy adult population

AIM: To investigate the associations between serum interleukin (IL) 18 concentrations and indices of lipid and carbohydrate metabolism in healthy adults. METHODS: Fasting serum concentrations of IL-18, glucose, total cholesterol, triglyceride, and high- and low-density lipoprotein cholesterols were measured in 570 apparently healthy adults. RESULTS: Univariate linear and partial regression analyses showed that the serum IL-18 concentration was positively correlated with serum triglyceride and glucose concentrations in both obese and diabetic subjects after controlling for the confounding effects of age, sex, and body mass index. CONCLUSION: IL-18 may be associated with obesity and glucose intolerance.     

Chromosome abnormalities in sperm of individuals with constitutional sex chromosomal abnormalities

The most common type of karyotype abnormality detected in infertile subjects is represented by Klinefelter's syndrome, and the most frequent non-chromosomal alteration is represented by Y chromosome long arm microdeletions. Here we report our experience and a review of the literature on sperm sex chromosome aneuploidies in these two conditions. Non mosaic 47,XXY Klinefelter patients (12 subjects) show a significantly lower percentage of normal Y-bearing sperm and slightly higher percentage of normal X-bearing sperm. Consistent with the hypothesis that 47,XXY germ cells may undergo and complete meiosis, aneuploidy rate for XX- and XY-disomies is also increased with respect to controls, whereas the percentage of YY-disomies is normal. Aneuploidy rates in men with mosaic 47,XXY/46,XY (11 subjects) are lower than those observed in men with non-mosaic Klinefelter's syndrome, and only the frequency of XY-disomic sperm is significantly higher with respect to controls. Although the great majority of children born by intracytoplasmic sperm injection from Klinefelter subjects are chromosomally normal, the risk of producing offspring with chromosome aneuploidies is significant. Men with Y chromosome microdeletions (14 subjects) showed a reduction of normal Y-bearing sperm, and an increase in nullisomic and XY-disomic sperm, suggesting an instability of the deleted Y chromosome causing its loss in germ cells, and meiotic alterations leading to XY non-disjunction. Intracytoplasmic injection of sperm from Y-deleted men will therefore transmit the deletion to male children, and therefore the spermatogenic impairment, but raises also concerns of generating 45,X and 47,XXY embryos.     

Complete absence of serum alpha-1-antitrypsin in conjunction with an apparently normal gene structure.

A family in which a Pinull allele for alpha-1-antitrypsin (A-1-AT) segregates has been studied in detail. Two homozygous sisters have no detectable A-1-AT in their serum as measured with the most sensitive methods currently available. Both have airways obstruction, and one has bullous emphysema. Heterozygotes for Pinull and the common normal allele PiM1 have half-normal serum concentrations of A-1-AT. A restriction enzyme analysis of chromosomal DNA of the two homozygotes and one heterozygote demonstrated the presence of an apparently complete structural gene for A-1-AT. Thus, the genetic defect in Pinull is not a complete or partial deletion of the structural gene. A base pair change that cannot be detected by the restriction enzymes used here, of course, cannot be excluded. Another possibility is a mutation outside the structural gene that affects the synthesis of the protein.     

Different chromosome Y abnormalities in Turner syndrome.

A 17-year-old phenotypically female girl was referred for evaluation because of short stature and primary amenorrhea. Cytogenetic analysis showed a mosaic 46,XY/45,X/47,XYY/46,X,idic(Yq)/47,XY,idic(Yq)/48,XXY,idic(Yq)/46,X,t(C;Y) karyotype. Conventional cytogenetic results were supplemented with fluorescence in situ hybridization (FISH) techniques to ensure a better characterization of abnormalities. By using FISH, a supernumerary marker chromosome derived from chromosome Y which could not be detected by conventional cytogenetics was revealed. Furthermore, additional abnormalities and their frequencies were highlighted by the application of DNA probes specific for X and Y chromosomes. Thus, FISH proved useful in determining low frequency cell lines which would need analysis of a large number of good quality metaphase spreads by conventional cytogenetic techniques: it helped in identifying the nature and the origin of unknown markers and rearrangements which have important implication in sexual differentiation and development of gonadal tumours.     

The association between arterial stiffness and left ventricular filling pressure in an apparently healthy Korean population

Aims

Transesophageal echocardiography (TEE) is the gold standard for the detection of thrombi in patients with atrial fibrillation (AF) before undergoing early electrical cardioversion (CV). However, TEE generates inconclusive results in a considerable number of patients. This study investigated the influence of contrast enhancement on interpretability of TEE for the detection of left atrial (LA) thrombi compared to conventional TEE and assessed, whether there are differences in the rate of thromboembolic events after electrical cardioversion.

Methods

Of 180 patients with AF (51 females, 65.2±13 years) who were referred to CV, 90 were examined with native imaging and contrast enhancement within the same examination (group 1), and 90 were examined with native TEE alone and served as control (group 2). Cineloops of the multiplane examination of the LA and LA appendage (LAA) were stored digitally before and, in group 1, after intravenous bolus application of a transpulmonary contrast agent. Images of group 1 were assessed offline and the diagnosis of LA thrombi was made semi-quantitatively: 1= thrombus present; 2=inconclusive result; 3=no thrombus. The presence of spontaneous echocontrast (SEC) was registered and flow velocity in the LA appendage (LAA-flow) was measured. All patients in whom CV was performed were followed up for 1 year or until relapse of AF. CV related adverse events were defined as any thromboembolic event within 1 week after CV.

Results

No serious adverse events occurred during TEE and contrast enhanced imaging. In group 1 atrial thrombi were diagnosed in 14 (15.6%) during native and in 10 (11.1%) patients during contrast enhanced imaging (p<0.001). Of the 10 patients with thrombi in the contrast TEE group, 7 revealed a decreased LAA-flow (≤0,3m/s) and 8 showed moderate or marked SEC. Uncertain results were significantly more common during native imaging than with contrast enhanced TEE (16 vs. 5 patients, p<0.01). Thrombi could definitely be excluded in 60 (66.7%) during conventional and in 75 patients (83.3%) during contrast enhanced TEE (p<0.01). CV was performed subsequently after exclusion of thrombi and at the discretion of the investigator. In group 1, 74 patients (82.2%) were cardioverted and no patient suffered a CV related complication (p=0.084). In group 2, 76 patients (84.4%) underwent CV, of whom 3 suffered a thromboembolic complication after CV (2 strokes, 1 peripheral embolism).

Conclusion

In patients with AF planned for CV contrast enhancement renders TEE images more interpretable, facilitates the exclusion of atrial thrombi and may reduce the rate of embolic adverse events.     

No evidence for constitutional chromosome instability in testicular cancer

Summary Chromosome aberrations in 20 lymphocytes of 20 patients with testicular germ cell tumors (TGCT) treated with surgery alone were compared with those of 20 cells from 20 healthy controls using standard G-banding technique. No increase in structural aberrations was found in the cancer group. An unexpected finding was that of more cells with losses of chromosomes being present in the control group. These losses predominantly affected small chromosomes in the control group, whereas the pattern of chromosome loss was different in the cancer group. The literature claiming increased chromosome instability in TGCT patients is reviewed. Point estimates and 95% confidence intervals to exclude such a hypothesis based on our results were calculated.