Mitochondrial Complex I Deficiency, Nuclear Type 27

A number sign (#) is used with this entry because of evidence that mitochondrial complex I deficiency nuclear type 27 (MC1DN27) is caused by homozygous or compound heterozygous mutation in the MTFMT gene (611766) on chromosome 15q22.

For a discussion of genetic heterogeneity of mitochondrial complex I deficiency, see 252010.

Clinical Features

Haack et al. (2012) reported 2 patients with mitochondrial complex I deficiency manifesting as Leigh syndrome (see 256000). One patient had developmental delay, hypotonia, and ataxia. Complex I deficiency was 12% of control values in muscle. The other patient had mental retardation, spasticity, gaze palsy, and partial optic atrophy. Complex I activity in this patient was 16% of normal. Activities of complexes II, III, and IV were within normal limits in both patients.

Molecular Genetics

In 2 unrelated patients with mitochondrial complex I deficiency nuclear type 27 manifesting as Leigh syndrome, Haack et al. (2012) identified homozygosity or compound heterozygosity for mutations in the MTFMT gene (611766.0001 and 611766.0004).