Marker chromosomes in parents of spontaneous abortuses

A rare chromosome 5 heterochromatic variant derived from insertion of 9qh satellite 3 sequences

A rare chromosome 5 heterochromatic variant not linked to any clinical sign was identified in a three-generation family. After performing conventional cytogenetics characterization, fluorescence in situ hybridization of D9Z1 indicated that the unusually large qh region of chromosome 5 originated from 9qh, whereas the centromere of the variant chromosome was 5-specific as demonstrated by primed in situ DNA labelling. FISH of probes targeting satellite 3 and beta-satellite sequences of 9qh showed that only satellite 3 sequences were present in the variant 5qh region.

C heterochromatin variation in couples with recurrent early abortions

The possible influence of the high polymorphic C heterochromatic regions of human chromosomes 1, 9, 16, and Y on meiotic chromosome segregation was investigated. Faulty chromosome segregation may be the result of either an abnormal quantity of C heterochromatin on the homologues, or disequilibrium between the homologues. The aim of our study was to determine whether either a variation in the amounts of total C heterochromatin or differences in the amounts of C heterochromatin between homologues could lead to faulty chromosome segregation. The study was performed on C banded metaphases obtained from peripheral lymphocyte cultures of 15 couples with recurrent early abortions and 15 control couples, all Caucasians. Analysis of variance was first performed on separate metaphases to measure intra-individual, inter-individual, and between population variation in a hierarchical model. Since the significant intra-individual differences covered the other parameters we performed, secondly, a one way analysis of variance on the mean values of metaphases per person in order to measure the inter-individual and between population variation. The results did not show a relationship between C heterochromatin lengths and occurrence of recurrent abortions.

Length of the Y chromosome and chromosomal variants in inpatient children with psychiatric disorders: two studies

In a study of 41 inpatient boys with psychiatric disorders, it was found that this group had significantly increased length of the long arm of the Y chromosome (Yq+) as compared to a normal control group. The length of the Y chromosome in the inpatient group correlated with psychiatric symptom severity, hyperactivity, parental psychopathology and paternal alcoholism. A further study of minor chromosomal variants in 56 inpatient boys and girls revealed no differences in individual or pooled variants in the patient group, as compared to the control group. However, those in the patient group with one or more variants showed more severe psychiatric and other psychosocial symptoms than those in the group without variants. Those who had both longer Y chromosomes and a minor chromosomal variant had more severe psychiatric symptom severity.

Aspects of evaluation, significance, and evolution of human C-band heteromorphism

The C-band heteromorphism may be evaluated in different forms. The results obtained from classification are easily influenced by subjective factors, and the conclusions of such types of data are acceptable only if they are well matched with a control. The length measurement is simple to obtain, and a quantitative presentation of the data, with correction for the contraction stage of the chromosomes, is considered the most efficient method to evaluate the C-band size heteromorphism. Excluding the acrocentrics, whose short arms present a complex heteromorphism, and the chromosome Y, whose variable C band is terminal, all others present C-band location heteromorphism except pair 16. It is possible to multiply the detectable heteromorphisms in some bands by using diverse staining methods. The present state of knowledge about the role of heterochromatin in the cell is analyzed, as is the effect of C-band variability on the phenotype, the reproductive fitness, and the individual viability. Although a great amount of data is available, no result can be considered definitive as yet. Aspects in which the use of C-band heteromorphisms are profitable are considered.

Chromosomal variants and male fertility

One hundred and forty-seven healthy men were investigated to determine whether there was an association between chromosomal variants and decreased fertility. Modern chromosome banding techniques detected normal variant karyotypes in 22 (15%) of these men. The fertility parameters of the 125 men with 46,XY karyotype were compared with those of the 22 men in the variant group. Analysis of the results showed that the two groups were not biologically different with respect to semen analysis and reproductive hormone levels.

Reproductive histories in a Norwegian twin population: evaluation of the maternal effect in early spontaneous abortion

An evaluation of the maternal effect on spontaneous abortion and the genetic contribution to various reproductive variables was made using like-sexed twins born between 1915–1946. Health and reproductive questionnaires were sent to 2,365 twin pairs listed in the Norwegian Twin Registry. Zygosity was determined by a questionnaire which proved to be 98% accurate in discriminating between monozygotic (MZ) and dizygotic (DZ) twins. Verification of the zygosity questionnaire was accomplished by blood cell marker zygosity determination in 200 twin pairs. Data from 428 monozygotic twin pairs (174 male pairs and 254 female pairs) were analyzed by a new model for qualitative traits and a striking maternal effect was found. The results suggested that over 54% of all women may belong to a high risk group who have approximately a 13% risk of early fetal loss. The incidence of first trimester abortions and spontaneous abortion reported by a sample of 915 like-sexed twin pairs and spouses was .079 and .089, respectively; there were no significant differences between male and female pairs.

Other reproductive variables were studied in both MZ and DZ twins including the age of menarche and menopause, the age at marriage and birth of the first child, and the interval between marriage and the first birth. These variables were examined for evidence of genetic effects and secular trends. The mean age of menarche had decreased significantly between the years 1915–1935 and 1936–1946. The secular trend appeared to be environmental in nature and accounted for more than 7% of the overall variation in age of menarche. Sixty-five percent of the variation in the age of menarche was attributed to genetic factors. The mean age of marriage and the mean age at the first birth decreased significantly between 1915–1935 and 1936–1946. Twins born between 1936–1946 also reported fewer pregnancies than did twins born between 1915–1946, but this was statistically significant among MZ twins only; no significant difference in the frequency of spontaneous abortions was found between the 1915–1935 and the 1936–1946 groups.

Although there were occasional groups in which differences were statistically significant, no general trends were identified in comparing couples who reported a spontaneous abortion with those who did not. Traits compared were: the age of menarche, age of marriage, age at first birth, the interval between marriage and first birth and the mean present age of the twins and spouses. Couples reporting a first trimester spontaneous abortion had significantly more total pregnancies than those not reporting a spontaneous abortion. Unaffected pregnancies were also significantly more numerous in couples with a spontaneous abortion compared to those without, suggesting over-compensation for fetal loss.

A maternal effect in spontaneous abortion was indicated by the correlation coefficients found; significant positive correlations were found in both MZ and DZ females but not in males. For total pregnancies and unaffected pregnancies, MZ twins, both male and female, had significant correlation coefficients while DZ twins did not.