[Newborn screening and variant analysis for methionine adenosyltransferase I/III deficiency]

To summarize newborn screening for methionine adenosyltransferase I/III (MAT I/III) deficiency in Quanzhou region of Fujian Province.

A total of 364 545 neonates were screened for inherited metabolic diseases by tandem mass spectrometry. High-throughput next generation sequencing combined with Sanger sequencing was used to detect potential variants in newborns with MAT I/III deficiency. Pathogenicity of suspected variants was predicted by using MutationTaster and HSF software.

Three newborns were identified with MAT I/III deficiency by newborn screening, which yielded an incidence rate of 1 in 121 515. Amino acid and acylcarnitine analysis suggested that the serum methionine of the three patients have increased to various extents. All patients showed normal growth and development during follow-up, and were found to carry MAT1A gene variants including two missense variants [c.776C>T (p.Ala259Val) and c.791G>A (p.Arg264His)] and a synonymous variant [c.360C>T (p.Cys120Cys)]. Among these, c.776C>T (p.Ala259Val) and c.791G>A (p.Arg264His) were known to be pathogenic, whereas c.360C>T (p.Cys120Cys) was a novel variant. Bioinformatics analysis suggested that this variant may alter RNA splicing and affect the structure and function of the MAT1A protein.

A systematic review of newborn screening for MAT I/III deficiency was provided. Discovery of the novel variant has enriched the variant profile of the MAT1A gene and provided a basis for the diagnosis of this disease.