The clinical diagnosis of Pallister syndrome in a 1-day-old white boy was confirmed by the presence of i(12p) in 100% of cells on direct bone marrow analysis. This is the second Pallister syndrome case in which cytogenetic diagnosis was made in bone marrow cells during the neonatal period. Other tissues analyzed in our patient included peripheral blood PHA-stimulated cultured lymphocytes and postmortem skin and lung cultured fibroblasts with 3%, 98.5%, and 97.5% of cells containing the i(12p), respectively. Serial skin fibroblast cultures re-established from frozen cells were analyzed sequentially over time for the isochromosome. There was slight reduction in the proportion of i(12p) cells until passage 15 with plateauing of the proportion of i(12p) cells at about 80% until culture senescence. Our review of such cytogenetic analyses suggests that in vivo and perhaps also in vitro isochromosome loss best explains the intra- and inter-tissue specific chromosomal mosaicism in the i(12p) syndrome. In any event, our results indicate that confirmation of the diagnosis in the neonatal period is possible by direct cytogenetic analysis of bone marrow.
A one-month-old child presenting with an aortic coarctation was found to have a left single transverse palmar crease and proportionate growth delay on physical examination, prompting a peripheral blood chromosome analysis. This showed a mosaic trisomy of chromosome 16, subsequently observed to decrease with the passage of time. As her phenotype was relatively benign, further analysis was performed to define more precisely the extent of her mosaicism given the supposedly lethal nature of the aneuploid cell line. Fluorescence in situ hybridisation and CA repeat polymorphism studies demonstrated the aneuploidy in multiple tissues, including the structurally affected aorta. Molecular analysis showed both maternal chromosomes 16 to be present in the trisomic cells, but maternal heterodisomy was not present in the diploid cells. Given the increasing number of individuals described with aneuploid mosaicism, we suggest that the study of multiple tissues is a necessary approach, the eventual goal being the appreciation of the relationship between the characteristics of a somatic mosaicism and the phenotype it imparts.
A child with manifestations of acrogeria and metageria, two "premature aging" syndromes, is presented. Because of his indistinct phenotype and because the question has been previously raised as to whether these conditions are separate, we propose the designation of acrometageria to describe this phenotypic continuum. As there is much in common clinically between acrometageria and the syndrome of type III procollagen deficiency (Ehlers-Danlos type IV), it might be presumed that a similar pathogenesis for acrometageria exists. This possibility has been tested previously, without demonstrating specific quantitative or qualitative deficits, but with some indirect evidence that collagen metabolism is deranged in these patients. One such crude indicator is the elevation of urinary hyaluronic acid levels, demonstrated in our patient and also observed in the phenotypically distinct Werner and Hutchinson-Gilford premature aging syndromes. On one hand, it could be argued that this supports the concept that premature aging syndromes exist as a biological continuum. On the other hand, it is equally valid to argue that syndromes of premature aging are so described merely because they include recognizable changes of normal aging and that the demonstration of an underlying mutation in a collagen gene, for example, invalidates their study as models of accelerated normal aging.
A 2-day-old infant was evaluated and suspected of having 22q11.2 deletion based on microcephaly, short and narrow palpebral fissures, a prominent nose with hypoplastic alae nasi, thin fingers, and a right aortic arch. He also had an imperforate anus, which is not in the del 22q11.2 syndrome. Karyotype analysis identified a ring 22, while fluorescence in situ hybridization (FISH) for the DiGeorge syndrome critical region identified a 22q deletion on the other homologue. The karyotype designation was 46,XY,r(22)(p13q13.3).ish del(22)(q11.2q11.2) (D22S75-). Both parents function in the mildly mentally retarded range. The father's karyotype was normal whereas the mother had the ring 22 that was inherited by her son. This is the first case reported for abnormalities on both 22 homologues.
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