Familial pericentric inversion of chromosome 19, inv(19) (p13q13) with a note on genetic counseling of pericentric inversion carriers

An inmate of a hospital for the mentally retarded was found during a cytogenetic screening programme to have karyotype 46,XY,inv(19)(p13q13)mat. Clinical, cytogenetic and family findings are presented and it is concluded that the chromosomes abnormality was probably not the cause of the patient's retardation. The problem of genetic counseling of inversion carriers is examined in some detail and estimates of risk are given.

Testicular chromosomal mosaicism and infertility

A healthy young man with azoospermia and no other endocrinological abnormalties was shown to have chromosomal mosaicism with the cytogenetic errors found only in testicular tissue. Three clones of cells were identified in both meiosis I and meiosis II by cytogenetic analysis of direct testicular smears. Peripheral blood karyotypes and buccal smear preparations revealed no abnormalities. It is postulated that the gonadal cytogenetic defects account for this patient's azoospermia. In addition, it is hypothesized that this type of incomplete spermatogenesis nonetheless produces sufficiet feedback material ("inhibin") so that FSH levels are not affected.

Drug-induced anaemias

Many drugs have been reported to have caused anaemia. The most serious form involves marrow aplasia, but the way in which this is produced is not understood. A number of drugs lead to megaloblastic anaemia and where this is caused by interference with dihydrofolate reductase the explanation is obvious. However, some substances, notably anticonvulsants, cause megaloblastic anaemia by some other mechanism. A number of drugs cause intestinal bleeding with anaemia as a result. Sideroblastic anaemia is a relatively rare condition, sometimes caused by drugs, particularly those used in the treatment of tuberculosis. Leukaemia very occasionally supervenes in patients with drug-induced aplastic anaemia.

Familial ovarian carcinoma

Familial aggregation of patients with ovarian carcinoma is unusual. A family with four affected members in three consecutive generations is described. The tumors were all of the serous papillary adenocarcinoma type. The pattern of appearance of the malignant disorder in the present family may be explained as the result of transmission of a dominant mutant autosomal gene. The future long term management of such a family might include prophylactic oophorectomy in certain family members, and possibly selective terminations of pregnancies with female fetuses in high-risk women.

Chromosome studies in 500 induced abortions

A survey of the chromosome constitution in 500 induced abortions (5-12 menstrual weeks) was undertaken over a period of 1 1/2 years. There were 34 cases (6.8%) of gross chromosome anomalies: 2 cases of trisomy A; 5 of trisomy C (including XXX and XXY); 1 of mosaic trisomy C; 4 of trisomy D; 2 of trisomy E; 2 of trisomy G; 1 of double trisomy E and G; 1 of XYY; 4 of monosmy C (including XO); 2 of mosaic monosomy C; 1 of mosaicism of ring D chromosome; 1 of extra small metacentric chromosome; 3 of triploidy (including triploidy with double trisomy C and G); and 5 of tetraploidy and its mosaicism. An increased risk for the occurrence of trisomic anomalies was found with advancing age of the mothers. In contrast, the production of monosomies was not age-related. Trisomies were the most common type of anomalies and were found almost at random, regardless of the characteristics of chromosomes. Neither satellited nor small chromosomes were predominantly involved in the formation of chromosome anomalies.

Comparison of chromosome breakages in lymphocytes and fibroblasts from control women and women taking oral contraceptives

To determine whether exposure to synthetic hormones resulted in increased chromosome damage in cells other than lymphocytes, we evaluated series of lymphocyte and fibroblast cultures from five control women and five women taking oral contraceptives (OC). The results of this study showed: (1) no difference in chromosome breakages between lymphocytes and fibroblasts; (2) no differences in breakages in replicate fibroblast cultures exposed to fetal calf serum, autologous serum, homologous serum, or homologous serum from OC users; (3) no difference in breakage between lymphocyte and fibroblast cultures from OC users, compared with lymphocyte and fibroblast cultures from control women; and (4) no increase in the frequency of cytogenetically aberrant stem-lines in fibroblast cultures from women taking OC. These findings suggest that synthetic hormones do not cause increased chromosome breakages in fibroblasts from women taking OC.

Observations of de novo clones of cytogentically aberrant cells in primary fibroblast cell strains from phenotypically normal women

In a recent study of chromosome breakage frequencies in 36 primary fibroblast cell strains derived from skin from 10 phenotypically normal women, we observed seven different clones of cells having consistent chromosomal abnormalities. Five of the stem lines were noted in cultures from "control" women and two in fibroblasts from women taking oral contraceptives. We observed aneuploid clones as well as stem lines bearing structural abnormalities (e.g., translocation, inversions). The various aberrant clones were found in cultures ranging in age from 41 to 144 days and comprised varying percentages of the cell populations ranging from 0.8% to virtually 100%. The possible evolution in culture of clones of cells having aberrant karyotypes should be considered in interpreting findings from fibroblast cultures initiated for clinical evaluation.

The significance of oral contraceptives in causing chromosome anomalies in spontaneous abortions

The significance of oral contraceptives in causing chromosome aberrations in the fetus was studied in 246 non-selected spontaneous abortuses using Q-banding technique. No significant difference in the frequency of abnormal karyotypes or in the sex ratio was found between 124 abortuses of women who had taken oral contraceptives in comparison with 122 abortuses of women who had never used oral contraceptives. The study did, however, show that women who had used oral contraceptives were significantly younger than women who had not used these pills. In addition, the gestational age of the chromosomally abnormal abortuses was on the average 6 days longer in the group of women who had used oral contraceptives than in the group who had not. The difference was significant only with regard to the karyotype 45,X.

Phosphoglucomutase phenotypes and prenatal selection. Studies of spontaneous and induced abortions

The PGM1 and PGM3 phenotypes were examined in extracts of chorionic tissue from 97 spontaneous and 266 induced abortions. Contamination by maternal tissue or blood cells was shown to be insignificant. A positive association was found between the PGM11 and PGM13 genes. No significant differences in phenotype distributions were found between the population of spontaneously aborted fetuses and the normal fetal or adult populations. Hence it was concluded that there is no evidence so far for prenatal selection operating in the PGM1 and PGM3 polymorphisms.