First Report of a Derivative Chromosome 13 with a Duplicated 11p15 Locus Associated with Silver-Russell Syndrome.

Silver-Russell Syndrome (SRS) is a disorder that is primarily characterised by intrauterine growth restriction which may occur asymmetrically or in whole, leading to a fetus being small relative to its gestational age. We present a female infant (proband) born in 2018 at a tertiary hospital in Muscat, Oman, with severe congenital anomalies. The proband carried a >25Mb duplication of the chromosomal 11p15-11pter locus of chromosome 13; creating a derivative chromosome 13 (der[13]) and was reported as 46,XX,der(13)add(11p15-11pter). A methylation-sensitive assay confirmed a diagnosis of SRS. Although the prognosis for SRS patients is generally good, the proband presented with a clinically severe phenotype culminating in death at the age of nine months. To the best of the authors' knowledge, this is the first report of a derivative chromosome 13 with a duplicated 11p15 locus in a patient with SRS.