Hereditary Disorders and Human Mutations of Iron-Sulfur Assembly Genes

Abstract

Multiple mitochondrial dysfunctions syndrome (MMDS) is a group of autosomal recessive mitochondrial disorders that is associated with deficiencies related to nuclear genes: ISCA2, ISCA1, NFU1, IBA57, and BOLA3. The syndromes are relatively new and recently discovered. Individuals with MMDS have reduced function of energy production stages in mitochondria. The dysfunctions are mostly related to iron-sulfur (Fe-S) clustering system (ISC) and its biogenesis. The signs and symptoms of the patients may begin early in life, and can be quite severe leading to death more or less during infancy. Affected individuals have various symptoms including brain dysfunction (encephalopathy), hypotonia, seizures, delayed developmental milestones, and cognition and psychomotor impairments. These individuals often have difficulty growing and gaining weight at the expected rate. Diagnosis of the disease can be challenging as in the case with most of the mitochondrial disorders. However, since the genetic causes of the MMDS are known, a laboratory test focusing on the causative genes will be helpful to determine the pathogenic mutations. This in turn would facilitate reducing the number of the diseases through carrier testing and genetic counseling and utilization of preimplantation genetic diagnosis in populations, especially those that display high rate of consanguinity, which are prone to have such autosomal recessive disorders.