A Novel De Novo KAT6B Mutation Causes Hypospadias in a Chinese Fetus at 29 Weeks Gestation.

KAT6B mutations are responsible for Say-Barber-Biesecker-Young-Simpson syndrome or Genitopatellar syndrome, with most mutations occurring in its exon 18. A pregnancy with normal early antenatal examination revealed the presence of hypospadias in the fetus but with no abnormal amniotic fluid volume in ultrasonography at 29th weeks' gestation. After amniocentesis, the trios' whole exome sequencing was performed and a novel frameshift mutation (KAT6B: exon10: c.2153_2159del, p. R718Lfs*3) was identified for her fetus, then verified by the parents as a de novo mutation. Following this couple's decision to induce labor, the appearance of the fetus had hypospadias but with a normal face and was able to be palpated for the patella. KAT6B mutations often occur with a variety of symptoms. To our acknowledgment, this is the first report of a novel de novo KAT6B mutation causing only hypospadias for the fetus, which further expands the spectrum of KAT6B variants and the genotype-phenotype relationship for this disease.