Congenital myopathy

Gene: MYMX

Green List (high evidence)

Comment on phenotypes: This gene has been associated with relevant phenotypes in OMIM (MIM #619941) and the OMIM record was last accessed on 18 December 2025.

Created: 18 Dec 2025, 10:14 p.m. | Last Modified: 18 Dec 2025, 10:14 p.m.

Panel Version: 6.44

The rating of this gene has been updated to green following NHS Genomic Medicine Service approval.

Created: 11 Dec 2025, 5:32 p.m. | Last Modified: 11 Dec 2025, 5:32 p.m.

Panel Version: 6.43

Comment on list classification: There is sufficient evidence available (three unrelated cases and functional work) for the association of biallelic MYMX variants with congenital myopathy. Hence, this gene can be promoted to green rating in the next GMS update.

Created: 23 Dec 2024, 4:42 p.m. | Last Modified: 23 Dec 2024, 4:42 p.m.

Panel Version: 5.8

PMID:35642635 reported two siblings from a single pedigree with a homozygous MYMX variant (p.Arg46Ter) and with clinical presentations including weakness of the facial musculature, hypomimic face, increased overbite, micrognathia, and facial dysmorphism. Both parents were heterozygous carriers of the SNV and were unaffected. The phenotype resembles Carey-Fineman-Ziter syndrome. Functional evidence showed that the variant prevents fusion of myoblasts from patient-derived induced pluripotent stem cells and mouse model recapitulated CFZS-like phenmoptype.

PMID:39668186 reported two unrelated patients with two different homozygous MYMX variants (p.Leu36Ter & p.Ter85TrpextTer41) and with a complex neuromuscular syndrome characterized by generalized hypotonia, congenital myopathy, facial nerve palsy, growth restriction and facial dysmorphism.

This gene has been associated with relevant phenotype in OMIM ( MIM #619941), but not in Gene2Phenotype.

Created: 23 Dec 2024, 4:39 p.m. | Last Modified: 23 Dec 2024, 4:39 p.m.

Panel Version: 5.4

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
?Carey-Fineman-Ziter syndrome 2, OMIM:619941

Publications

• 35642635
• 39668186

Green List (high evidence)

The PMID: 39668186 describes additional 2 (to previous 2; total 4) patients with congenital myopathy with recognizable facial palsy, growth restriction, and dysmorphism. Enough evidence for the green rating. Probably the gene should be added also to the short stature panel?
Sources: Literature

Created: 16 Dec 2024, 8:12 a.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
congenital myopathy with recognizable facial palsy, growth restriction, and dysmorphism

Publications

• PMID: 39668186