Prepair 1000+

Gene: MUT

Green List (high evidence)

Isolated methylmalonic aciduria is found in patients with mutations in the MUT gene causing partial, mut(-), or complete, mut(0), enzyme deficiency. Variable severity and age of onset:

• Infantile completely deficient (mut0) or non-B12-responsive (clbB) is the most common phenotype and presents during infancy. Infants are normal at birth, but develop lethargy, vomiting, and dehydration within the first few months of life. They may also exhibit hepatomegaly, hypotonia, encephalopathy, metabolic acidosis, ketosis and ketonuria, hyperammonemia, and hyperglycemia.

• Partially deficient (mut-) or B12-responsive (cblA, cblD, rarely cblB) is an intermediate phenotype that can occur in the first few months or years of life. Symptoms include feeding problems, failure to thrive, hypotonia, and developmental delay. Some have protein aversion and vomiting, and lethargy after protein intake.

HGNC approved symbol/name: MMUT *
Is the phenotype(s) severe and onset <18yo? Yes
Treatments available: cobalamin, N-carbamylglutamate, carnitine, diet, liver transplant
Known technical challenges? No
Gene reported in 3 independent families: Yes

* NOTE: gene previously called MUT

Created: 29 Jan 2025, 4:33 a.m. | Last Modified: 29 Jan 2025, 4:34 a.m.

Panel Version: 1.1367

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Methylmalonic aciduria, mut(0) type, MIM# 251000