Down's syndrome: chromosome analysis of 362 cases in Hungary.

A survey is given of the karyotypes observed in 362 children clinically diagnosed as cases of Down's syndrome from whom material was sent to 8 collaborating cytogenic laboratories in Hungary during the period 1965-1974. The sample studied cytogenetically constitutes about 20% of all children born in Hungary in this decade with Down's syndrome. The ways in which patients were selected for cytogenetic examinations could not be specified. In the sample, standard trisomy 21 was found in 91.7%, translocations in 3.9% and mosaicism in 4.4%. The mean age of the mothers of the children investigated was 29.05 years, a relatively low figure which may be explained by the decrease of the mean maternal age over the last decades.     

Familial Down's syndrome.

A family is reported in which the same mother conceived two children with trisomy 21. The pregnancy with the second affected child was interrupted after diagnostic amniocentesis. Maternal chromosome analysis was normal. This family and those previously reported suggest that there is an increased recurrence risk of trisomy 21 after the birth of an affected individual, possibly caused by a genetic tendency for non-disjunction. After the birth of a child with Down's syndrome, amniocentesis and chromosome analysis of cultured amniotic fluid cells is indicated in each further pregnancy, irrespective of maternal age.     

Meiosis in a male with Down's syndrome

Summary The chromosomes in mitotic and meiotic phases were investigated in a male Down's syndrome case, aged 45. Information was obtained that based on blood and tunica vaginalis cultures, the somatic chromosome complement was found to possess 47 chromosomes with the standard 21-trisomy, and further that the majority of cells from biopsied testicular specimens examined showed the chromosome number 47 in spermatogonia, and 22 autosomal elements consisting of 21 bivalents and a trivalent, together with an X-Y bivalent in the first spermatocytes. The seminiferous tubules contained no mature spermatozoa.Contribution No. 688 from the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo. This paper is dedicated to Professor Sajiro Makino, Zoological Institute, Hokkaido University, Sapporo, in honor of his sixtieth birthday, June 21, 1966.     

Direct analysis of thymic function in children with Down's syndrome

BACKGROUND: Down's syndrome (DS) is characterized by several immunological defects, especially regarding T cell compartment. DS is considered the best example of accelerated ageing in humans. Direct observations of the thymus have shown that in DS this organ undergoes severe histological and morphological changes. However, no data on its capacity to generate T cells are present in the literature. Here, using a new technology based upon real time PCR, we have investigated the capacity of the thymus to produce and release newly generated T lymphocytes (the so called "recent thymic emigrants", RTE) in children with DS. METHODS: We studied 8 children affected by DS, aged 2-7 years, compared with 8 age- and sex-matched healthy controls. Flow cytometry was used to determine different lymphocytes subsets. Real time PCR with the Taqman system was used to quantify the amount of RTE, i.e. peripheral blood lymphocytes that express the T cell receptor rearrangement excision circles (TREC). RESULTS: In comparison with control children, those with DS had a significant lower number of TREC+ peripheral blood cells. Moreover, in DS children but not in controls, a strong negative correlation between age and the levels of TREC+ cells was found. CONCLUSIONS: The direct measure of thymic output indicates that the impairment of the organ results in a reduced production of newly generated T cells. This observation could suggest that cytokines able to modulate thymic function, such as interleukins, could be useful to improve the functionality of the organ and to treat the immunodeficiency present in DS subjects.     

Reproduction in a female patient with Down's syndrome

Summary A non-mongoloid boy born to a mongoloid mother is described. He showed aplasia of the left 5th finger and some clinical and dermatoglyphic features frequently found in Down's syndrome. Chromosome analysis revealed few hyperdiploid but no G-trisomic cells. An undetected G-trisomy mosaic, or a mechanism of extrachromosomal inheritance, and an embryonic development in a pathological milieu are discussed.Supported by the Fritz-Thyssen-Stiftung     

Craniofacial anthropometric analysis in Down's syndrome patients

Past investigations of Down's syndrome (DS) have indicated that there are marked abnormalities in the craniofacial morphology. The aim of this study was to establish the craniofacial anthropometric variables which discriminate DS group from healthy population and also to observe the changes occurring with growth. Using noninvasive method of craniofacial anthropometry, craniofacial pattern profile (CFPP) analysis (from twenty-five anthropometric measurements per person) was performed in 104 DS individuals and 365 healthy controls, aged seven to fifty-seven and divided into four age ranges. Z-scores were calculated for each variable and the variations in the craniofacial region have been identified by multivariate discriminative analysis. The results showed that three variables (head length (g-op), head circumference (OFC) and outer canthal distance (ex-ex) were responsible for 85.68% variability (p < 0.001). The analysis of z-scores showed that the majority of variables were in subnormal (under -2 SD) and normal range (from -2SD to +2SD), but none of them was in the supernormal range (over the +2SD). Some craniofacial characteristics are age-related. On the basis of craniofacial anthropometric traits it was possible to separate even 91.35% of DS patients from the healthy population. It could be concluded that these findings demonstrate the usefulness of application of CFPP in defining abnormal craniofacial dimensions in DS individuals.