Biomedical subjects
Publications and source records attributed to D M Cox.
G banded chromosomal analysis of cells from a routine amniocentesis revealed a Y to X translocation in the fetus. The same unbalanced translocation was found in the mother who was disproportionately short. H-Y antigen titers in the mother were intermediate and steroid sulfatase activity was in the normal female range. At birth the baby exhibited few dysmorphic features but appeared to have short limbs.
The derivation of a 46,XY,del(1)(q42) chromosome complement in a mentally retarded child from a maternal paracentric inv(1)(q42q44) is discussed and the clinical findings are compared to previously reported cases of the same deletion syndrome.
A newborn with partial trisomy 2q, due to a maternal (2;6) translocation is presented. The baby had microcephaly, a prominent forehead, hypertelorism, a broad nose with a flat nasal bridge, a long philtrum, micrognathia, and low set ears which are common to cases with partial 2q trisomy. Additional findings of aniridia and marked corneal pathology are reported.
With the increased use of routine ultrasonography at the time of genetic amniocentesis, twins are increasingly likely to be discovered at the time when the procedure is to be carried out. In the presence of twins the likelihood of finding an abnormality may be significantly increased, but at the same time problems such as discordance between the twins for the abnormality, or the inability to test both twins may occur. This altered situation may affect the parents' decision as to whether or not to undertake amniocentesis, and the need for additional counseling prior to proceeding with the amniocentesis is stressed.
The knowledge that the biochemical lesion associated with Tay-Sachs disease is demonstrable in many tissues, and in particular in cultured fibroblasts, suggested that ultrastructural lesions might also accompany hexosaminidase A deficiency in cultured fibroblasts. Electron microscopic studies on six human skin fibroblast lines and four amniotic fluid fibroblast lines, biochemically confirmed to be deficient in hexosaminidase A, showed characteristic cytoplasmic inclusions not observed in any normal lines studied. Up to 60 of these abnormal cytoplasmic inclusions were observed in full cell cross sections in all affected lines examined.
Fibroblast cell-lines derived from four patients with clinically confirmed Duchenne's muscular dystrophy were examined by Duchenne's muscular dystrophy were examined by transmission electron microscopy. Cell-lines from patients with Duchenne's muscular dystrophy could be distinguished from normal cell-lines by the presence of characteristic inclusion bodies.
The use of electron microscopy as a further method of diagnosis of disease in cultured skin fibroblasts and cultured amniotic fluid fibroblasts is presented. It was demonstrated that Tay-Sachs disease, Fabry's disease, and metachromatic leukodystrophy had distinctive abnormalities in both cultured skin fibroblasts and cultured amniotic fluid fibroblasts. It was shown that control of culturing conditions made it possible to distinguish normal cell lines from certain cell lines carrying known genetic diseases.
A series of 18 sublines deficient for one or two chromosomes was isolated in vitro from a pseudodiploid Chinese hamster cell population treated appropriately with Colcemid to obtain maximal induction of aneuploidy. Chromosomes 10 and 11 were the most frequently involved and, to a lesser extent, chromosome 9 and the partially deleted 6. Since analysis of chromosome banding patterns did not reveal any evidence of chromosome rearrangement, it was concluded that entire chromosomes were absent, and thus the sublines are presumed to be monosomic. The monosomic state was quickly lost during serial culture, and the 15th passage after isolation, the monosomic cell type accounted for less than 50% of the cell population in over half the sublines. This was due to a shift in chromosome number back to 22, apparently by reacquistion of the absent chromosome, or to the appearance of tetraploidy.
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