Editor—Silver-Russell syndrome (SRS) is a condition characterised by pre- and postnatal growth restriction, triangular facies, and limb and truncal asymmetry.1 2 The aetiology of the syndrome is heterogeneous and there is no clearly established Mendelian basis. A number of chromosomal abnormalities are associated with the SRS phenotype in a minority of cases. To date, 37 cases of maternal uniparental disomy for chromosome 7 (mUPD(7)) have been reported, representing approximately 10% of all cases.3-18

Five mUPD(7) probands were found to show heterodisomy for the complete length of chromosome 7, ruling out the exposure of a mutant recessive gene as the basis of SRS.19 These findings indicate that one or more genes on chromosome 7 are imprinted and involved in the pathogenesis of the syndrome. Lack of a paternal gene(s) expression could result in the syndrome, as could the overexpression of a maternal gene involved in growth inhibition. Recently, two unrelated SRS probands with maternal duplications of 7p have been reported defining a candidate gene region that may contain the gene(s) responsible for the phenotype associated with mUPD(7).20 21 In addition, a single case of partial mUPD(7) has been reported with biparental inheritance for the majority of the chromosome, with mUPD(7) 7q32-qter when analysed using fluorescent microsatellite PCR.22 This indicates that there are at least two imprinted regions on chromosome 7 that are involved in the pathogenesis of SRS. …