What question did this study set out to answer?

To report a case of mitochondrial myopathy associated with a novel variant in TAMM41 and its clinical implications.

January 10, 2026American Journal of Medical Genetics Part A0 citations

A Novel Variant in the TAMM41 ‐Associated Mitochondrial Myopathy

Q: What does this research mean for the field?

A Brazilian patient with a novel TAMM41 variant exhibited motor regression and marked pulmonary dysfunction, highlighting the severe impacts of this mitochondrial myopathy. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

CMCristiane Araujo Martins MorenoMendelics CGClara Camelo GontijoHospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo AFAlulin Tácio Quadros Santos Monteiro FonsecaHospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo

Key Result

The Brazilian patient with a novel TAMM41 variant showed motor regression and marked pulmonary dysfunction, highlighting the severe impacts of this mitochondrial myopathy.

Key Points

To report a case of mitochondrial myopathy associated with a novel variant in TAMM41 and its clinical implications.
Long-term follow-up of a Brazilian patient with a novel TAMM41 variant and a previously identified pathogenic variant.
Assessment of clinical features including developmental delay and motor function.
Muscle biopsy examination for COX and SDH staining levels.
Patient showed mild developmental delay and independent gait acquisition.
Subsequent motor regression and weakness occurred, leading to severe pulmonary dysfunction.
Muscle biopsy revealed decreased COX and SDH staining, indicating potential diagnostic importance.

Structured PICO

Population

1 Brazilian patient with TAMM41-associated mitochondrial myopathy harboring a novel TAMM41 variant in compound heterozygosity with a previously described pathogenic variant.

This case expands the genetic spectrum of TAMM41-related mitochondrial myopathy and highlights decreased COX and SDH staining on muscle biopsy as a potential diagnostic clue.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

ABSTRACT Pathogenic variants in TAMM41 were recently linked to mitochondrial myopathy, presenting with neonatal hypotonia, generalized weakness, developmental delay, ptosis, and ophthalmoparesis. Here, we present a long‐term follow‐up of an additional case, a Brazilian patient harboring a novel TAMM41 variant in compound heterozygosity with a previously described pathogenic variant. Patient exhibited mild developmental delay, acquired independent gait, but subsequently developed motor regression and weakness associated with recurrent infections, severe axial involvement, and marked restrictive pulmonary dysfunction. Muscle biopsy revealed decreased COX and SDH staining, which may serve as an important diagnostic clue for this condition. This case expanded the genetic spectrum of TAMM41 ‐related mitochondrial myopathy and provided a brief review of disorders associated with reduced SDH staining.

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