A Novel Frameshift Variant in the hnRNPK Gene Associated with Au-Kline Syndrome Identified During Prenatal Diagnosis: A Case Report.

Au-Kline syndrome is a rare disease of major pediatric concern, characterized by intellectual disability, facial deformities, heart defects, and abnormal development of connective tissue and bone. Loss-of-function variants of hnRNPK gene have been proven to be significantly related to Au-Kline syndrome. In this report, a novel hnRNPK gene frameshift variant [NM_031263.4:c.1074dupG:p.M359Dfs*4] was found in a 12-week-old fetus with ultrasound abnormalities including cystic hygroma of the neck, bilateral branchial cysts, and a megabladder. This case report describes a novel frameshift duplication variant of hnRNPK and enriches the mutation database of this gene. Moreover, cystic hygroma of the neck and bilateral branchial cysts on prenatal ultrasound were first discovered in patients with Au-Kline syndrome, which provides a reference for the subsequent prenatal diagnosis of Au-Kline syndrome.