Chromosome 7 Isodisomy in a Child with Silver-Russell Síndrome

Abstract

Silver-Rusell syndrome is a rare genetic disease. There is evidence that the genetic causes of the disorder are heterogeneous, with predominant alterations in the imprinted regions of chromosomes 11 and 7, in addition to other genomic alterations, such as chromosomal structural aberrations, single nucleotide polymorphisms, copy number variations, and small insertions and deletions. The most prevalent clinical manifestations include prenatal and postnatal growth retardation, dysmorphic features, and feeding difficulties. We present a case of a 4-year-old boy with phenotypic features consistent with Silver-Russell syndrome. The sample was subjected to conventional karyotyping analysis. The analysis was also conducted using the SALSA MLPA Probemix ME032-A1 UDP7-UDP14 and Applied Biosystems CytoScan 750K Suite. MS-MLPA analysis revealed the presence of hypermethylation in the <em>GRB-10</em> and <em>MEST</em> genes on chromosome 7. SNP-array analysis revealed a loss of heterozygosity (LOH) at 7q11.22q31.1 (38.7 Mb). The methylation of the genes involved in this epigenetic event, in conjunction with LOH and the clinical characterization of this child, indicates that the origin of the disease is due to an isodisomy of maternal chromosome 7. This report of a child who exhibits the clinical characteristics of SRS and presents a UPD of chromosome 7, most likely originating from the mother, once again demonstrates the involvement of these genes in SRS despite the incomplete understanding of the underlying mechanism. A multidisciplinary strategy has been proposed for the follow-up and treatment of this disease according to its etiology in the proband.