A novel MLL2 gene mutation in a Korean patient with Kabuki syndrome

Abstract

Kabuki syndrome (KS) is a rare genetic disease with a distinctive dysmorphic face, intellectual disability, and multiple congenital abnormalities. KS is inherited in an autosomal dominant manner. As the primary cause of KS, MLL2 mutations have been identified in 56-76% of affected individuals who have been tested, suggesting that there may be additional genes associated with KS. Recently, a few KS individuals have been found to have de novo partial or complete deletions of an X chromosome gene, KDM6A, which encodes a histone demethylase that interacts with MLL2. Nevertheless, mutations in MLL2 are the major cause of KS. Although there are a few reports of KS patients in Korea, none of these had been confirmed by genetic analysis. Here, we report a case of a Korean patient with clinical features of KS. Using direct sequencing, we identified a frameshift heterozygous mutation for MLL2: (c.5256_5257delGA;p.Lys1753Alafs*34). Clinically, the patient presented with typical facial features, and diagnosis of KS was based on the diagnostic criteria. While KS is a rare disease, other malformations that overlap with those found in individuals with KS are common. Hence, the diagnosis of KS by mutational analysis can be a valuable method for patients with KS-like syndromes. Furthermore, in the near future, other genes could be identified in patients with KS without a detectable MLL2 mutation.

Keywords: KDM6; KS-associated genes; Kabuki syndrome; MLL2 mutation.

Fig. 1

Mutation analysis of the MLL2 gene. Direct sequencing chromatograms displaying the heterozygote frameshift mutation for MLL2 (c.5256_5257delGA;p.Lys1753Alafs*34) in exon 22 (arrow) in a patient (A and B). (A) Patient: forward strand, (B) patient: reverse strand, (C) father, and (D) mother.