Congenital myopathy

Gene: MT-TE

Red List (low evidence)

After NHS Genomic Medicine Service consideration, the rating of this gene has been updated to red. GLH review concluded that mitochondrial myopathies are not good fit for this panel. R300 Possible mitochondrial disorder - whole mitochondrial genome sequencing would be the more appropriate test.

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: As reviewed below, patients with MT-TE variants are reported with either congenital myopathy or adult-onset myopathy. As there are >3 unrelated cases with congenital myopathy, this gene can be considered for promotion to green rating in the next GMS update.

Created: 28 Jun 2025, 6:09 p.m. | Last Modified: 28 Jun 2025, 6:09 p.m.

Panel Version: 6.28

PMID:7726155 - The m.14709 C>T variant in MT-TE gene has been reported in a family, where the proband and his sister presented with congenital myopathy and mental retardation and subsequently developed cerebellar ataxia. Other family members had adult-onset diabetes mellitus with or without muscle weakness (myopathy). Primary myoblast, but not fibroblast, cultures containing high proportions of mtDNA with the above variants exhibited impaired mitochondrial translation.

PMID:10392369 - A mother and son affected with diabetes mellitus and myopathy were identified with a m.14709 C>T variant. The son was reported with hypotonia and developmental delay, and was diagnosed as having mitochondrial myopathy based on muscle biopsy at the age of five years.

PMID:15607216 - Three patients from two unrelated families were reported with the identification of m.14709 C>T variant. The first patient is a 21-month-old child with severe congenital myopathy, respiratory distress and mild mental retardation. The other two patients are 51- and 55-year-old siblings with slowly progressive myopathy and diabetes mellitus.

PMID:21194154 - Eight patients from seven families with reversible infantile cytochrome c oxidase deficiency myopathy were identified with a homoplasmic m.14674T>C or m.14674T>G variant. Two of these patients had the clinical diagnosis of congenital myopathy and five others had mitochondrial myopathy.

Created: 28 Jun 2025, 5:37 p.m. | Last Modified: 28 Jun 2025, 5:37 p.m.

Panel Version: 6.25

Mode of inheritance
MITOCHONDRIAL

Phenotypes
inborn mitochondrial myopathy, MONDO:0009637; congenital myopathy, MONDO:0019952

Publications

• 7726155
• 10392369
• 15607216
• 21194154

Green List (high evidence)

The 14709 C>T pathogenic variant in MT-TE has been reported in families with congenital myopathy, and the m.14674T>C pathognenic variant causes reversible COX deficiency which usually presents with hypotonia in the first year of life.

Created: 24 Jun 2025, 10:53 a.m. | Last Modified: 24 Jun 2025, 10:53 a.m.

Panel Version: 6.10

Mode of inheritance
MITOCHONDRIAL

Publications

• 7726155
• 21931168
• 33128823
• 15607216

Mode of pathogenicity
Other