PRENATAL AND POSTNATAL-GROWTH FAILURE ASSOCIATED WITH MATERNAL HETERODISOMY FOR CHROMOSOME-7

The association of maternal uniparental disomy for chromosome 7 and po stnatal growth failure has been reported in four cases and suggests th e presence of genomic imprinting of one or more growth related genes o n chromosome 7. However, in the reported cases, the possibility of hom ozygosity for a recessive mutation could not be excluded as the cause of the growth failure as in all cases isodisomy rather than heterodiso my for chromosome 7 was present. We report a case of prenatal and post natal growth retardation associated with a prenatal diagnosis of mosai cism for trisomy 7 confined to the placenta. DNA typing of polymorphic markers on chromosome 7 has established that the zygote originated as a trisomy 7 with two maternal and one paternal chromosomes 7 with sub sequent loss of the paternal chromosome resulting in a disomic child w ith maternal heterodisomy for chromosome 7. The growth failure seen in this child with heterodisomy 7 lends strong support to the hypothesis of imprinted gene(s) on chromosome 7.