Uniparental disomy of chromosome 16: a case report with a new cardiac malformation Abstracts from the 53rd European Society of Human Genetics (ESHG) Conference: e-Posters

Introduction: Maternal uniparental disomy of chromosome 16 [UPD(16)mat] is the most often reported UPD other than UPD(15). In literature there is not a specific phenotype associated with upd(16)mat and few follow-up data are reported. Materials and methods: We present the case of a 1-y.o. male of a healthy non-consanguineous parents. In prenatal diagnosis IUGR, polydramnios and single umbilical artery was reported. He born late preterm, small for gestational age, and showed facial dysmorphisms and congenital malformations (esophageal atresia, cardiac defects, mild bone alterations, hypospadias). Transesophageal echocardiography detected persistency of left superior vena cava draining into the left atrium through an unroofed coronary sinus. Brain ultrasound showed dilated and asymmetric lateral ventricles. At present, cognitive and language abilities are adequate for age but he has mild gross motor delay. Genomic DNA was extracted from peripheral blood and analyzed by SNP-array (Cytoscan HD; Thermo Fisher Scientific). Results: SNP-array analysis showed a 147 Kb homozygous 16p13.3 microdeletion and a 114 kb 16q24.3 microtriplication, both segregated from the mother. Region of Homozigosity (ROH) analysis showed two ROH of 7 and 13 Mb on chromosome 16 compatible with the presence of UPD(16) of maternal origin. The possible presence of a residual mosaic trisomy 16 was excluded by karyotype analysis and FISH. Conclusions: This is an additional case of the phenotypic characterization of UPD(16)mat. To date, it is the first time that an unroofed coronary sinus is described within cardiac malformations associated with UPD(16)mat. Moreover, according to literature data, it confirms the need to extend follow-up.