An analysis of the distribution of hetero- and isodisomic regions of chromosome 7 in five mUPD7 Silver-Russell syndrome probands

Silver-Russell syndrome (SRS) shares common features of intrauterine growth retardation (IUGR) and a number of dysmorphic features including lateral a symmetry in about 50% of subjects. Its genetic aetiology is complex and mos t probably heterogeneous. Approximately 7% of patients with SRS have been f ound to have maternal uniparental disomy of chromosome 7 (mUPD7). Genomic D NA samples from five SRS patients with mUPD7 have been analysed for common regions of isodisomy using 40 polymorphic markers distributed along the len gth of chromosome 7. No regions of common isodisomy were found among the fi ve patients. It is most likely that imprinted gene(s) rather than recessive mutations cause the common phenotype. Heterodisomy of markers around the c entromere indicated that the underlying cause of the mUPD7 is a maternal me iosis I non-disjunction error in these five subjects.