Editor—Recently, Bernasconiet al 1 and Shafferet al 2 described carriers of isochromosomes 2p (i(2p)) and 2q (i(2q)). In both patients maternal uniparental disomy (UPD) (2), the exceptional inheritance of both chromosomes 2 from the mother, was detected. Isochromosome formation of both the short and the long arms of a chromosome in one carrier is a rare event. In addition to isochromosomes 2, there exist single reports on only isochromosomes 4p and 4q,3 isochromosomes 7p and 7q,4 and isochromosomes 9p and 9q.5 In these cases, the parental origin was determined and was mostly maternal.

The phenotypes of the carriers of i(2p) and i(2q) and maternal UPD(2) are rather inconsistent. Bernasconi et al 1 reported a healthy woman with a history of five spontaneous abortions. In contrast, the patient of Shafferet al 2 showed features similar to those of three maternal UPD(2) patients ascertained because of confined placental mosaicism (CPM) for trisomy 2.6-8 In all these four patients, severe intrauterine growth retardation with …