Novel compound heterozygous MVK variants cause early-onset mevalonic aciduria in a Chinese infant.

Mevalonate kinase deficiency (MKD) is a rare autosomal recessive autoinflammatory disorder caused by mevalonate kinase (MVK) gene mutations, with phenotypes ranging from mild hyper-IgD syndrome (HIDS) to severe mevalonic aciduria (MA). Here, we report a 7-month-old Chinese male infant presenting with neonatal-onset MA. The proband presented with growth retardation, intractable diarrhea, recurrent fever, generalized rash, progressive hepatosplenomegaly, and persistent systemic inflammation. Laboratory tests revealed marked leukocytosis, elevated C-reactive protein, hyper-IgD and increased urinary mevalonic acid. Whole-exome sequencing identified two novel compound heterozygous MVK variants: c.64G > A (p.Val22Met) and c.1063G > C (p.Ala355Pro). Both variants were absent in global population databases. In silico analyses, including cross-species conservation, structural modeling, and pathogenicity prediction, confirmed significant structural perturbations. The patient achieved sustained remission with canakinumab. This is the first worldwide report of the MVK c.1063G > C variant causing severe MA, expanding the MVK mutational spectrum in Chinese populations.