Mitochondrial Complex I Deficiency, Nuclear Type 9

A number sign (#) is used with this entry because of evidence that mitochondrial complex I deficiency nuclear type 9 (MC1DN9) is caused by homozygous mutation in the NDUFS6 gene (603848) on chromosome 5p15.

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

Clinical Features

Kirby et al. (2004) reported 2 unrelated patients with complex I deficiency. Both patients had lethal infantile mitochondrial disease with death within the first 2 weeks of life.

Spiegel et al. (2009) reported 2 unrelated infants, both of Jewish Caucasus descent, with fatal infantile lactic acidosis resulting from severe complex I deficiency.

Molecular Genetics

Kirby et al. (2004) reported 2 unrelated patients with complex I deficiency caused by different homozygous mutations in the NDUFS6 gene (603848.0001; 603848.0002).

Spiegel et al. (2009) reported 2 unrelated infants, both of Jewish Caucasus descent, with fatal infantile lactic acidosis resulting from severe complex I deficiency due to a homozygous mutation in the NDUFS6 gene (C115Y; 603848.0003). Complex I activity was about 50% or less in muscle biopsies. The Jewish population of the Caucasus region of central Asia is believed to have originated from southern Iran and is a genetically isolated community.