A molecular anatomical analysis of mosaic trisomy 16

Abstract

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.

Trisomy 16 and trisomy 16 mosaicism: A review

“…This may reflect a more general mechanism for selection against cells with abnormal karyotypes in tissues with rapid cell turnover [Benn, 1977]. In the one case in which trisomy 16 was noted in a high proportion of lymphocytes, the proportion of abnormal cells declined rapidly over a period of 12 months [Greally et al, 1996]. A decline in the proportion of cells with trisomy 16 has also been noted in serial studies on fibroblasts [Gilbertson et al, 1990].…”

Intrauterine Growth Retardation Fetus with Trisomy 16 Mosaicism

“…However, IUGR, aortic coarctation, congenital heart defect, intestinal atresia, craniofacial dysmorphisms, and various anomalies have been reported [5–7, 12–16]. …”

Trisomy 16q in a female newborn with a de novo X;16 translocation and hypoplastic left heart

“…HLH encompasses a spectrum of heart anomalies characterized by obstructive lesions of the left side of the heart accompanied by varying degrees of underdevelopment of the aorta, aortic valve, left ventricle, mitral valve, and left atrium. Interestingly, HLH has been reported in patients with Turner syndrome [Natowicz, 1988], in cases of 16q duplications [Eriksson et al, 1971, Hatanaka et al, 1982, and in trisomy 16 mosaicism [Greally et al, 1996]. In the case of Turner syndrome HLH has been described in monosomy X patients rather than deletions of the short arm of the X chromosome.…”

“…A good number of the reported cases with 16q duplications have been seen in association with left-side abnormalities of the heart. These abnormalities include HLH as well as other abnormalities like aortic coarctation or hypoplasia [Buckton et al, 1981;Greally et al, 1996;Hahm et al, 1987]. It is quite likely that chromosome 16 contains critical genes for development of the left heart.…”