[Clinical and genetic analysis of a child with Niikawa-Kuroki syndrome].

Objective: Clinical examination and molecular genetic analysis were carried out for one case with special facial features with developmental retardation, hearing impairment and cleft lip and palate.

Methods: The intelligence test, hearing test, and MRI test were performed. At the same time, the blood were collected to detect the copy number variation of the whole genome with the chromosomal karyotype analysis and the chromosomal microarray analysis (CMA). And the whole exome sequencing (WES) was used to analyze the pathogenic variant.

Results: The children had mild mental retardation and the IQ was 61. There was moderate hearing loss in both ears(left ear 60 dB, right ear 65 dB). And bilateral horizontal hypoplasia of semicircular canal was found by cranial MRI test. No copy number abnormality was found by chromosome karyotype analysis and chromosome microarray analysis in peripheral blood. And whole exome sequencing suggested that there was heterozygous pathogenic variants in KMT2D gene (p.Leu545Argfs*385).

Conclusion: The patient has a peculiar face and multiple system defects, and was diagnosed as Niikawa-Kuroki syndrome type I by KMT2D gene variant. The whole exome sequencing is helpful for the diagnosis of complex genetic diseases.