A gonadal mosaicism novel KMT2D mutation identified by haplotype construction and clone sequencing strategy

• Published in: Clinica chimica acta 2022-06, Vol.531, p.197-203
• Main Authors: Guo, Liangjie, Zhang, Mengting, Gao, Yue, Qin, Litao, Xia, Hailan, Liu, Lin, Wang, Hongdan
• Format: Article
• Language: English
• Subjects: Gonadal mosaicism; Haplotype construction; Kabuki syndrome; KMT2D mutation
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2022.04.008

•Identification and validation of a novel “de novo” missense heterozygous mutation of the KMT2D.•Evolutionary conservation and 2D structure of KMT2D prediction.•Haplotype construction and clone sequencing; the mother may be gonadal mosaicism. Here we reported a pedigree that gave birth to two characteristic clinical signs of Kabuki syndrome daughters. They had an intellectual disability with special facial features. Their eyebrows were relatively wide and the rear 1/3 of the eyebrows were light and sparse. Their eyes were long, narrow, valgus and strabismus. Their noses were broad at the root and flat at the tip. They also had skeletal dysplasia, mainly manifested in the short second knuckle of the little fingers of both hands. Genetic studies showed a novel de novo KMT2D variant (c.16343G > C; p.R5448P) as a cause of Kabuki syndrome. It was very unlikely that the same de novo mutation occurred in two members of a family. Gonadal mosaicism in one of the parents was suspected. Haplotype construction and clone sequencing were used for mutation source analysis. Finally, we inferred that the haplotype from the mother (Gdel-G-C-T-A) contained the pathogenic mutation. A gonadal mosaicism novel KMT2D mutation was identified in their mother.