Variable clinical expression of mosaic trisomy 16 in the newborn infant

Abstract

Trisomy 16 is common in embryos and fetuses aborted early during development. Mosaicism for trisomy 16 is sometimes encountered during prenatal diagnosis, particularly with chorionic villi biopsy specimens, and, until recently, was thought to be confined to the placenta. However, recently, several liveborn infants with trisomy 16 mosaicism have been described. We report on an additional liveborn infant with trisomy 16 mosaicism and compare the clinical findings with those of the previously reported cases in an attempt to delineate a mosaic trisomy 16 syndrome. Cytogenetic analysis from our patient showed that there was a different proportion of abnormal cells in different tissues and that the anomaly was undetectable in blood lymphocyte cultures. This observation was consistent with some of the previous reports. DNA analysis of parents and child was carried out using a polymorphic dinucleotide marker that maps to the long arm of chromosome 16. This analysis showed that the extra chromosome 16 in the infant was maternal in origin and suggested that the nondisjunction was probably a first meiotic division error. Our results suggest that an investigation of multiple tissues is required before concluding that mosaicism is confined to the placenta. We conclude that a finding of trisomy 16 mosaicism at prenatal diagnosis should be regarded with extreme caution. This diagnosis may be associated with a highly variable phenotype that may occasionally be compatible with extrauterine life.

Trisomy 16 and trisomy 16 mosaicism: A review

“…The high frequency of fetal death, acute pregnancy complications, and extreme values in maternal serum hCG are consistent with abnormal placental function. Although it may also appear to be reasonable to associate the growth retardation with placental functional insufficiency, it should be noted that in some instances the growth retardation had an asymmetric component that would be more consistent with localized effects in the fetus [Gilbertson et al, 1990;Devi et al, 1993;Kalousek et al, 1993]. This may be similar to the situation in trisomy 18 mosaicism in which the asymmetric growth retardation may correlate with a local distribution in the proportion of trisomic cells [Rao et al, 1978].…”

Trisomy 16 Mosaicism in Amniotic Fluid Cell Cultures

“…The clinical features associated with trisomy 16 mosaicism may be directly attributable to the tissue-specific distribution of cells with the additional chromosome 16 (Gilbertson et al, 1990;Devi et al, 1993). It is also possible that fetal abnormality, notably growth retardation, could be attributable to the presence of a high proportion of trisomic cells in extra-fetal tissues creating the condition of abnormal placentation (Kalousek et al, 1993).…”

Trisomy 16 Mosaicism at Chorionic Villus Sampling and Amniocentesis with a Normal Physical and Intellectual Outcome

“…Congenital malformations, most commonly a cardiac septal defect, are seen in 71% of cases of amniocentesisdiagnosed mosaic trisomy 16 proceeding through to live birth [1][2][3][4][5][6][7] . Information regarding long-term follow-up for infants in whom mosaic trisomy 16 was identified antenatally remains sparse.…”