Isochromosome Xq in Klinefelter syndrome: report of 7 new cases.

In this collaborative study we report on 2 prenatally and 5 postnatally diagnosed cases with a 47,X,i(Xq),Y chromosomal constitution. Excepting tall stature, the 5 adult patients showed all typical manifestations of Klinefelter syndrome. Taken together with previously reported cases, these data suggest that Klinefelter syndrome with isochromosome Xq has a favorable prognosis with normal mental development, and with normal-to-short stature. The prevalence of this Klinefelter variant is calculated to be between 0.3-0.9% in males with X chromosome polysomies.

[Extremely high alpha-fetoprotein levels in a puncture specimen with few cells following amniocentesis and interpretation by sonography]. / Extrem hoher Alpha-Fetoproteinspiegel in einem zellarmen Punktat nach Amniozentese und Klärung durch Sonographie.

We report on a prenatal diagnosis with high alpha-fetoprotein level and a positive acetylcholinesterase activity in a presumptive amniotic fluid. Ultrasonographic examinations revealed a hydropic fetus with a nuchal cystic hygroma. Chromosome analysis of the aborted foetus ascertained the suspected Turner syndrome. The highly elevated alpha-fetoprotein concentration and the positive acetylcholinesterase activity as well as the absence of the cells in the fluid make it clear, that the punctate originated from a cystic hygroma. Other cases from the literature are discussed.

Ring chromosome 15 in a male adult with radial defects. Evaluation of the phenotype.

A case of a 37-year-old male patient with r(15) is reported. At birth he was small and light for dates. His main features are: short stature, head circumference in the lower normal range, mid-facial hypoplasia, radial defects, and mental retardation. Evaluation of the phenotype led us to conclude that a wide spectrum of malformations is possible. There is apparently no strong correlation between karyotype and phenotype.

[Cytogenetic paternity test in father-daughter incest (case report) (author's transl)]. / Zytogenetischer Paternitätsnachweis bei Vater-Tochter-Inzest.

Cytogenetic test for paternity proved superior to serological tests in a case in which possible father-daughter incest was to be proven or disproven. Of seven fetal chromosomal markers three were derived from the putative father, two from the mother and two paternal markers were present in both fetus and mother as a consequence of the incest. The fetus was homozygous for a paternal marker on chromosome 22.

[Prenatal sex determination via GBN saliva test. A comparison with the results of prenatal chromosomal analysis]. / Pränatale Geschlechts-bestimmung durch den GBN-Speicheltest. Ein Vergleich mit den Ergebnissen der pränatalen Chromosomendiagnostik.

In 114 pregnant women the results of the GBN saliva test were compared with the results of sex determination by prenatal chromosomal analysis. GBN test results predicting boys corresponded in 40,7% of the cases with male karyotypes, whereas test results predicting girls corresponded in 56,5% with female karyotypes. Mean age of the women tested was 35,9 +/- 3,6 years. The test results in women aged 35 or younger did not show a better correlation with the chromosomal sexing than in older women (46,5% and 48,4%). Saliva tests performed in the 16th to 20th week of gestation corresponded to the same extent with the chromosomal sex of the fetuses as those performed in the 21st to 32nd week of gestation (48,5% and 46,2%). The mode of ascertainment of the pregnant women and other factors possibly influencing the results are discussed. It is concluded that the GBN saliva test is not suitable for prenatal sex prediction in women of the age group investigated.

Chromatid exchanges in ataxia telangiectasia, Bloom syndrome, Werner syndrome, and xeroderma pigmentosum.

The frequency of BrdU-induced sister chromatid exchanges (SCE) in cultured lymphocytes from patients with ataxia telangiectasia, Werner syndrome, and xeroderma pigmentosum was normal. The rate was increased in xeroderma pigmentosum following exposure to ultraviolet light and spontaneously raised in the Bloom syndrome. Quadriradial exchanges between homologous chromosomes in Bloom syndrome not only involve sister chromatids but also homologous (non-sister) chromatids. This could result in the formation of recombinant chromosomes and is viewed as a genetically determined form of increased somatic recombination in man. Endoreduplicated metaphases showed 'twin' and 'single' exchanges in a 1:2 ratio. This suggests a comparable frequency of exchanges at both divisions and provides evidence for the polarity of the chromatid subunits and the presence of a single chain of DNA.

Partial trisomy 13 presumably due to recombination in an inversion heterozygote and by unequal crossing-over.

Two unrelated infants with partial trisomy 13 for the distal of the long arm are described. In one, a familial pericentric inversion is present in three generations and crossing-over in the inversion loop is considered as cause of partial trisomy 13. The other showed a tandem duplication of the distal half of the long arm of chromosome 13 beyond 13q14. This is interpreted to have arisen by unequal crossing-over in mispaired synapsis. It is suggested that recombination rather than breaks is a distinctive although rare cause of human chromosomal imbalance.

Toxicity of antibiotics on cultured human skin fibroblasts.

Human diploid fibroblasts cultured in Dulbecco's Modified Eagle's medium (DME) were exposed to different concentrations of 15 antibiotics to determine the limiting toxic concentration. The number of cells surviving after antibiotic treatment was given as the index of toxicity. No visible chromosomal damage could be detected when half the maximal toxic concentration was applied. The maximum limiting concentration was found to be the same for both the preconfluent and postconfluent phases.