Parental origin effects in human trisomy for chromosome 14q: implications for genomic imprinting.

Parental origin specific congenital anomalies have been noted in patients with uniparental disomy of the long arm of human chromosome 14 (UPD14). This suggests the presence of imprinted genes, consistent with observations of imprinting in the region of syntenic homology in the mouse. It is not known whether the distinct defects reported for paternal and maternal UPD14 are the result of biallelic expression or absence of expression of imprinted genes. Furthermore, identification of the genes responsible would be facilitated by a higher resolution map of the imprinted region(s) involved. Subjects with partial trisomy for chromosome 14 (Ts14) have been reported and hence also have an alteration in the dosage of their parental chromosomes. In this study, we have carried out genotype-phenotype correlations considering the parental origin of the extra chromosome in previously reported cases of maternal and paternal partial Ts14. The analysis has provided evidence of a correlation between distal maternal Ts14 and anomalies including low birth weight, short philtrum, and small hands. The clinical features found in the maternal and paternal trisomies are compared with those associated with maternal and paternal UPD14 and their significance is discussed in relation to genomic imprinting on chromosome 14.