Prenatal detection of TAR syndrome in a fetus with compound inheritance of an RBM8A SNP and a 334‑kb deletion: a case report

Thrombocytopenia-absent radius syndrome (TAR) is a rare genetic disorder that is characterized by the absence of the radius bone in each forearm and a markedly reduced platelet count that results in life-threatening bleeding episodes (thrombocytopenia). Tar syndrome has been associated with a deletion of a segment of 1q21.1 cytoband. The 1q21.1 deletion syndrome phenotype includes Tar and other features such as mental retardation, autism and microcephaly. This study describes a case of a prenatally diagnosed fetus with compound inheritance of a small (334-kb) deletion, as detected by array-comparative genomic hybridization, and a 5' untranslated region (UTR) low-frequency allele (rs139428292) in gene RBM8A as detected by Sanger sequencing. The study describes the first case of prenatal analysis of TAR syndrome in a fetus with compound inheritance of a 334-kb deletion in the 1q21.1 region and a low-frequency 5' UTR single nucleotide polymorphism, and provides confirmation of the causal nature of the RBM8A gene in the diagnosis of TAR syndrome.