Identification of a pathogenic variant and pre-implantation genetic testing for a Chinese family affected with split-hand/foot malformation.

Split-hand/foot malformation is a serious congenital limb malformation characterized by syndactyly and underdevelopment of the phalanges and metatarsals. In this study, we reported a case of a fetus with hand-foot cleft deformity. Whole exome and Sanger sequencing were used to filter out candidate gene mutation sites and provide pre-implantation genetic testing(PGT) for family members. Genetic testing results showed that there was a homozygous mutation c.786G>A (p.Trp262*) in the fetal WNT10B, and both parents were carriers of heterozygous mutations. PGT results showed that out of the two blastocysts, one was a heterozygous mutant and the other was a homozygous mutant. All the embryos had diploid chromosomes. The heterozygous embryo was transferred, and a singleton pregnancy was successfully achieved. This study suggests that homozygous mutations in WNT10B are the likely cause of hand-foot clefts in this family. For families with monogenic diseases, preimplantation genetic testing can effectively prevent the birth of an affected child only after identifying the pathogenic mutation.