[Novel frameshift mutations in SALL4 in two Chinese families with Okihiro syndrome]

In the present study, clinical manifestations of two Chinese Okihiro syndrome families were analyzed, and genetic detections were performed on the two probands by exome sequencing and verified by Sanger sequencing for family members to determine the biological pathogenesis. Prenatal diagnoses were provided for three high-risk fetuses. The affected members exhibited a wildly spectrum of phenotypes, including ultrasound abnormalities of skeletal system (radius deformity and abnormal posture), and cardiac system (persistent common arterial trunk and ventricular septal defect) in the prenatal period of family 1, the severe phenotypes (grossly shortened and deformed forearm, Duane's anomaly and hearing loss), and the mild ones (usually only thenar dysplasia, or short radius styloid process). Two SALL4 variants, c.844delC p.(Q282Kfs*8) and c.2210delG p.(G737Vfs*23), have been identified respectively in two probands, and c.2210delG of SALL4 gene was unreported previously. The two variants were verified in all affected individuals, not in normal family members. Genotyping results of three fetuses indicated that one fetus was normal, and the two fetuses with heterozygous variation were affected. The two variants of SALL4 gene, c.844delC p.(Q282Kfs*8) and c.2210delG p.(G737Vfs*23), were the molecular pathological cause of Okihiro syndrome in the present study and enriched the spectrum of SALL4 variants. Our study provides accurate prenatal genetic diagnosis for the two families to avoid the birth of affected children.