[Analysis of a child with Microvillus inclusion disease due to variants of MYO5B gene and a literature review].

Objective: To explore the clinical and genetic characteristics of a neonate with Microvillus inclusion disease (MVID).

Methods: A neonate with MVID admitted to the First Affiliated Hospital of Zhengzhou University in May 2019 was selected as the study subject. Clinical data were collected. Whole exome sequencing (WES) was carried out, and candidate variants were verified by Sanger sequencing and multiple ligation-dependent probe amplification (MLPA). A literature was also carried out to summarize the clinical and genetic characteristics of MVID.

Results: The prematurely born neonate had presented with unexplained refractory diarrhea and metabolic acidosis. Active symptomatic treatment was ineffective, and the child had died at 2 months old. WES revealed that he had harbored compound heterozygous variants of the MYO5B gene, namely c.1591C>T (p.R531W) and deletion of exon 9. Sanger sequencing showed that the R531W variant was inherited form his father, and MLPA confirmed that the exon 9 deletion was inherited from his mother. Seven children with MVID were reported in China, of which one was lost during follow-up and six had deceased. One hundred eighty eight patients were reported worldwide and only one was cured. The clinical features of MVID had included refractory diarrhea, metabolic acidosis and poor prognosis.

Conclusion: The child was diagnosed with MVID due to the compound heterozygous variants of the MYO5B gene, which has provided a basis for genetic counseling and prenatal diagnosis.