Mitochondrial Complex I Deficiency, Nuclear Type 1

A number sign (#) is used with this entry because of evidence that mitochondrial complex I deficiency nuclear type 1 (MC1DN1) is caused by homozygous mutation in the NDUFS4 gene (602694) on chromosome 5q11.

Description

Isolated complex I deficiency is the most common enzymatic defect of the oxidative phosphorylation disorders (McFarland et al., 2004; Kirby et al., 2004). It causes a wide range of clinical disorders, ranging from lethal neonatal disease to adult-onset neurodegenerative disorders. Phenotypes include macrocephaly with progressive leukodystrophy, nonspecific encephalopathy, hypertrophic cardiomyopathy, myopathy, liver disease, Leigh syndrome (see 256000), Leber hereditary optic neuropathy (535000), and some forms of Parkinson disease (see 556500) (Loeffen et al., 2000; Pitkanen et al., 1996; Robinson, 1998).

Genetic Heterogeneity of Complex I Deficiency

Mitochondrial complex I deficiency shows extreme genetic heterogeneity and can be caused by mutation in nuclear-encoded genes or in mitochondrial-encoded genes. There are no obvious genotype-phenotype correlations, and inference of the underlying basis from the clinical or biochemical presentation is difficult, if not impossible (summary by Haack et al., 2012). However, the majority of cases are caused by mutations in nuclear-encoded genes (Loeffen et al., 2000; Triepels et al., 2001).

Complex I deficiency resulting from mutation in nuclear-encoded genes include MC1DN1, caused by mutation in the NDUFS4 gene (602694); MC1DN2 (618222), caused by mutation in the NDUFS8 gene (602141); MC1DN3 (618224), caused by mutation in the NDUFS7 gene (601825); MC1DN4 (618225), caused by mutation in the NDUFV1 gene (161015); MC1DN5 (618226), caused by mutation in the NDUFS1 gene (157655); MC1DN6 (618228), caused by mutation in the NDUFS2 gene (602985); MC1DN7 (618229), caused by mutation in the NDUFV2 gene (600532); MC1DN8 (618230), caused by mutation in the NDUFS3 gene (603846); MC1DN9 (618232), caused by mutation in the NDUFS6 gene (603848); MC1DN10 (618233), caused by mutation in the NDUFAF2 gene (609653); MC1DN11 (618234), caused by mutation in the NDUFAF1 gene (606934); MC1DN12 (301020), caused by mutation in the NDUFA1 gene (300078); MC1DN13 (618235), caused by mutation in the NDUFA2 gene (602137); MC1DN14 (618236), caused by mutation in the NDUFA11 gene (612638); MC1DN15 (618237), caused by mutation in the NDUFAF4 gene (611776); MC1DN16 (618238), caused by mutation in the NDUFAF5 gene (612360); MC1DN17 (618239), caused by mutation in the NDUFAF6 gene (612392); MC1DN18 (618240), caused by mutation in the NDUFAF3 gene (612911); MC1DN19 (618241), caused by mutation in the FOXRED1 gene (613622); MC1DN20 (611126), caused by mutation in the ACAD9 gene (611103); MC1DN21 (618242), caused by mutation in the NUBPL gene (613621); MC1DN22 (618243), caused by mutation in the NDUFA10 gene (603835); MC1DN23 (618244), caused by mutation in the NDUFA12 gene (614530); MC1DN24 (618245), caused by mutation in the NDUFB9 gene (601445); MC1DN25 (618246), caused by mutation in the NDUFB3 gene (603839); MC1DN26 (618247), caused by mutation in the NDUFA9 gene (603834); MC1DN27 (618248), caused by mutation in the MTFMT gene (611766); MC1DN28 (618249), caused by mutation in the NDUFA13 gene (609435); MC1DN29 (618250), caused by mutation in the TMEM126B gene (615533); MC1DN30 (301021), caused by mutation in the NDUFB11 gene (300403); MC1DN31 (618251), caused by mutation in the TIMMDC1 gene (615534); MC1DN32 (618252), caused by mutation in the NDUFB8 gene (602140); and MC1DN33 (618253), caused by mutation in the NDUFA6 gene (602138).

Complex I deficiency with mitochondrial inheritance has been associated with mutation in 6 mitochondrial-encoded components of complex I: MTND1 (516000), MTND2 (516001), MTND3 (516002), MTND4 (516003), MTND5 (516005), MTND6 (516006). Most of these patients have a phenotype of Leber hereditary optic neuropathy (LHON; 535000) or Leigh syndrome. Features of complex I deficiency may also be caused by mutation in other mitochondrial genes, including MTTS2 (590085).

Clinical Features

Van den Heuvel et al. (1998) reported a patient with fatal multisystemic complex I deficiency and homozygous mutation in the NDUFS4 gene. He had normal muscle morphology and a remarkably nonspecific fatally progressive course without increased lactate concentrations in body fluids. He presented at 8 months of age with severe vomiting, failure to thrive, and hypotonia. At the age of 13 months, he showed severe psychomotor retardation, convulsions, bradypnea, cyanosis, hypotonia, and depressed tendon reflexes. Cerebral MRI showed generalized brain atrophy and symmetric basal ganglia abnormalities. He died of cardiorespiratory failure at the age of 16 months.

Budde et al. (2000) reported 2 unrelated patients, born to consanguineous parents, with complex I deficiency and decreased activity of complex III. The female patient showed, within 1 week of age, hypotonia, absent eye contact, lethargy, and failure to thrive. At 3 months of age, microcephaly was present and lactic acidemia with an increased lactate/pyruvate ratio was found. CT and MRI showed bilateral basal ganglia hypodensities. The child died at 3 months of age. Except for hypospadias noted at birth, the male patient appeared normal until the age of 7 weeks at which time muscular hypotonia and lack of visual and auditive attention were observed. At the age of 3 months he was found to have elevated lactate levels in the blood. Cranial MRI showed hyperintense signals resembling those found in Leigh syndrome (see 256000). Cardiac ultrasound showed concentric hypertrophy of the left ventricle with hypercontractility. He died from cardiocirculatory insufficiency.

Benit et al. (2003) identified 2 sisters in a consanguineous family with complex I deficiency nuclear type 1 and Leigh syndrome.

Neuroradiologic Features in Patients with Known Nuclear or Mitochondrial Mutations

Lebre et al. (2011) performed a retrospective review of the neuroradiologic features of 30 patients with complex I deficiency due to either nuclear (10 patients) or mitochondrial (20 patients) mutations. All patients had MRI abnormalities in the brainstem that were hyperintense on T2-weighted images and hypointense on T1-weighted images. Brainstem lesions were associated with at least 1 striatal anomaly (putamen or caudate) in 27 of 30 patients. Ten patients had thalamic anomalies, all of whom also had striatal lesions. Caudate lesions were more common in patients with mtDNA (50%) compared to those with nuclear (10%) mutations. Stroke-like lesions predominantly affecting the gray matter were observed in 40% of patients with mtDNA mutations, but in none of patients with nuclear mutations. A diffuse supratentorial leukoencephalopathy involving the deep lobar white matter was observed in over 50% of patients with nuclear mutations, but in none of patients with mtDNA mutations. Cerebellar hyperintensities were found in 45% of patients, regardless of the mutated genome, but cerebellar atrophy was found only in those with mtDNA mutations. All 10 patients studied had increased lactate on magnetic resonance spectroscopy.

Patients with Unknown Mutations

Morgan-Hughes et al. (1979) presented the first report of isolated complex I deficiency. Two sisters had a mitochondrial myopathy characterized by weakness, marked exercise intolerance, and fluctuating lactic acidemia. Increased weakness was precipitated by unaccustomed exertion, fasting, or alcohol. During exercise, blood lactate and pyruvate levels rose abruptly and markedly. Mitochondrial respiratory rates were greatly decreased with all NAD-linked substrates, but normal with succinate and with TMPD plus ascorbate. Mitochondrial cytochrome components were normal. Morgan-Hughes et al. (1979) concluded that the defect was at the level of the NADH-CoQ reductase complex.

Land et al. (1981) reported a young man with weakness, exercise intolerance, muscle wasting, and exercise-induced lactic acidosis. Biochemical studies showed deficiency of NADH-cytochrome b reductase. The defect appeared to be situated between NADH dehydrogenase and the CoQ-cytochrome b complex. Land et al. (1981) postulated a derangement of a nonheme iron-sulfur center.

Moreadith et al. (1984) reported a male infant with complex I deficiency who developed respiratory distress and hypoglycemia on the first day of life. At 6 weeks, he showed generalized hypotonia and concentric biventricular cardiac hypertrophy on echocardiography. Lactic acidemia was progressive, and the child died at 16 weeks of age. Skeletal muscle biopsy showed giant mitochondria in which both inner and outer membranes were arranged in whorls. Biochemical studies of mitochondria from 4 organs showed a moderate to profound decrease in the ability to oxidize pyruvate, malate plus glutamate, citrate and other NAD-linked respiratory substrates. Oxidation of succinate was normal. Further studies localized the defect to the inner membrane mitochondrial NADH-ubiquinone oxidoreductase. Electron paramagnetic resonance spectroscopy showed almost total loss of the iron-sulfur clusters of complex I. The most pronounced deficiency was in skeletal muscle, the least in kidney mitochondria. There was no record of a similar problem in the family and the parents were not related. Since the parents subsequently had a normal male child, Moreadith et al. (1984) excluded mitochondrial inheritance and suggested either autosomal recessive inheritance or a de novo dominant mutation.

In a study on tissue from the patient reported by Moreadith et al. (1984), Moreadith et al. (1987) found that antisera against complex I immunoprecipitated NADH-ferricyanide reductase from the control but not the patient's mitochondria. Immunoprecipitation and SDS-PAGE of complex I polypeptides demonstrated that most of the 25 polypeptides comprising complex I were present in the affected mitochondria. A more detailed analysis using subunit selective antisera against the main polypeptides of the iron-protein fragments of complex I showed a selective absence of the 75- and 13-kD polypeptides, suggesting a deficiency of at least 2 polypeptides comprising the iron-protein fragment of complex I. Moreadith et al. (1987) hypothesized that the genetic defect involved transcription or translation of the polypeptides, the transport of these polypeptides into the mitochondria, or the site of assembly of complex I.

Hoppel et al. (1987) investigated a mitochondrial defect in a male infant with fatal congenital lactic acidosis, high lactate-to-pyruvate ratio, hypotonia, and cardiomyopathy. His sister had died with a similar disorder. Resting oxygen consumption was 150% of controls. Pathologic findings included increased numbers of skeletal muscle mitochondria (many with proliferated, concentric cristae), cardiomegaly, fatty infiltration of the viscera, and spongy encephalopathy. Mitochondria from liver and muscle biopsies oxidized NADH-linked substrates at rates 20 to 50% of controls, whereas succinate oxidation by muscle mitochondria was increased. Mitochondrial NADH dehydrogenase activity (complex I) was 0 to 10% of controls, whereas activity of other electron transport complexes in related enzymes was normal. Hoppel et al. (1987) suggested a familial deficiency of a component of mitochondrial NADH dehydrogenase proximal to the rotenone-sensitive site.

Wijburg et al. (1989) reported a sibship born to healthy first-cousin Moroccan parents with 2 well-studied children with severe congenital lactic acidosis as well as 4 others with a clinical history compatible with the same defect. Treatment initially by artificial respiration and peritoneal dialysis followed later by high doses of menadione effected a remarkable recovery. Despite the parental consanguinity, Barth et al. (1989) suggested that the defect in this family involved the mitochondrial genome: they detected a possible deletion in the mitochondrial-encoded MTND3 protein in skeletal muscle.

Slipetz et al. (1991) studied 2 unrelated patients with complex I deficiency with different phenotypes. One patient had hypotonia, seizures, and hepatomegaly, and died of lactic acidosis on day 13 of life. Biochemical analysis of complex I subunits showed absence of a 20-kD protein predicted to be encoded by the nuclear genome. Complex I activity was 6% of control values. The other child had marked growth and developmental delay, and showed altered neurologic function and seizures beginning at age 8 years. Other features included ptosis, sensorineural hearing loss, hypotonia, incoordination, and hyporeflexia. Mild facial coarseness was also observed. No complex I subunit abnormalities were detected by immunoprecipitation or Western blot analysis, but complex I activity was 15% of control values.

Bentlage et al. (1995) showed deficits of specific complex I protein subunits in patients with complex I deficiency.

Dionisi-Vici et al. (1997) reported 2 infant sibs with fatal progressive macrocephaly and hypertrophic cardiomyopathy. Onset of symptoms was at the end of the first month of life with massive brain swelling. Light microscopy showed extensive small-vessel proliferation and gliosis. Complex I deficiency was detected in cultured fibroblasts, skeletal muscle, and heart muscle.

Procaccio et al. (1999) reported 2 unrelated patients with fatal infantile lactic acidosis associated with isolated complex I deficiency. Reexpression of complex I subunits and recovery of complex I activity in patients' mitochondria after transnuclear complementation by nuclei from cells without mitochondria enabled the authors to infer the nuclear DNA origin of the defects in both patients. Patient 1 showed reduced amounts of the 24- and 51-kD subunits and normal amounts of all the other investigated subunits. Patient 2 showed severely decreased amounts of all the investigated subunits. Patient 1 developed generalized hypotonia with poor gesticulation in the first 24 hours of life. By day 2, he was very floppy with poor response to painful stimuli and required ventilatory assistance. Hepatic enlargement was noticed, and chest x-rays showed slight cardiomegaly. Cranial ultrasonography showed brain edema, and severe lactic acidosis was detected. The patient went into a deep coma and died at 11 days. Patient 2 vomited frequently in the first 2 weeks of life and at 5 weeks showed deterioration of neurologic status with hypotonia, weakness, and lethargy. In the first month, the head circumference was noted to be rapidly increasing from 33 to 40 cm. Computed tomographic scan showed a very hypodense brain with increased brain volume and extensive cerebral edema. Marked metabolic acidosis with hyperlactic acidemia was demonstrated. Despite intensive care, the neurologic state worsened rapidly and brain death occurred at 6 weeks of age. Autopsy showed acute necrotizing encephalopathy, but no hypertrophic cardiomyopathy.

In a study of 157 patients with respiratory chain defects, von Kleist-Retzow et al. (1998) found complex I deficiency in 33% and combined complex I and IV deficiency in another 28%. The main clinical features in this series were truncal hypotonia (36%), antenatal (20%) and postnatal (31%) growth retardation, cardiomyopathy (24%), encephalopathy (20%), and liver failure (20%). No correlation was found between the type of respiratory chain defect and the clinical presentation, but complex I and complex I+IV deficiencies were significantly more frequent in cases of cardiomyopathy (p less than 0.01) and hepatic failure (p less than 0.05), respectively. The sex ratio was skewed toward males being affected with complex I deficiency. A high rate of parental consanguinity was observed in complex IV (20%) and complex I+IV (28%) deficiencies.

Loeffen et al. (2000) retrospectively examined clinical and biochemical characteristics of 27 patients, all of whom presented in infancy and young childhood with isolated enzymatic complex I deficiency established in cultured skin fibroblasts; common pathogenic mtDNA point mutations and major rearrangements were absent. Clinical phenotypes included Leigh syndrome in 7 patients, Leigh-like syndrome in 6, fatal infantile lactic acidosis in 3, neonatal cardiomyopathy with lactic acidosis in 3, macrocephaly with progressive leukodystrophy in 2, and a residual group of unspecified encephalomyopathy in 6, subdivided into progressive (in 4) and stable (in 2) variants.

Molecular Genetics

Smeitink and van den Heuvel (1999) reviewed the nuclear gene mutations that had been identified in patients with isolated complex I deficiency, including a 5-bp duplication in the NDUFS4 gene (602694.0001).

In 2 unrelated patients with complex I deficiency nuclear type 1 and decreased activity of complex III, Budde et al. (2000) demonstrated homozygous mutations in the NDUFS4 gene (602694.0002 and 602694.0003). The mutations segregated with the disorder in both families.

In a patient with complex I deficiency resulting in Leigh syndrome, Petruzzella et al. (2001) identified a homozygous nonsense mutation in the NDUFS4 cDNA (W15X; 602694.0004). Both parents were heterozygous for the mutation.

In 2 sisters in a consanguineous family with complex I deficiency and Leigh syndrome, Benit et al. (2003) identified a homozygous splice site mutation in the NDUFS4 locus (602694.0005).

In 3 sibs, born of Ashkenazi Jewish parents, with complex I deficiency nuclear type 1 manifesting as Leigh syndrome Anderson et al. (2008) identified a homozygous 1-bp deletion (462delA; 602694.0006) in the NDUFS4 gene. The mutation was identified by linkage analysis followed by candidate gene sequencing. Each unaffected parent and an unaffected sib were heterozygous for the mutation. The carrier frequency of the mutation, ascertained from 5,000 controls of Ashkenazi Jewish descent, was found to be 1 in 1,000, consistent with a founder effect in this population. Based on the results, Anderson et al. (2008) used prenatal testing in this family to help the parents produce an unaffected child.

Assereto et al. (2014) identified homozygosity for the 462delA mutation in the NDUFS4 gene in 2 sibs with mitochondrial complex I deficiency who were not of Ashkenazi Jewish descent.

Genotype/Phenotype Correlations

Mutations in the nuclear-encoded genes NDUFS1, NDUFS4, NDUFS7, NDUFS8, and NDUFV1 result in neurologic diseases, mostly Leigh syndrome or Leigh-like syndrome. Mutations in NDUFS2 and NDUFV2 have been associated with hypertrophic cardiomyopathy and encephalomyopathy. Mutations in the mitochondrial-encoded genes are associated with a wide variety of clinical symptoms, ranging from organ-specific to multisystem diseases (Benit et al., 2004).

Swalwell et al. (2011) reviewed the clinical and genetic findings in a large cohort of 109 pediatric patients with isolated complex I deficiency from 101 families. Pathogenic mtDNA mutations were found in 29% of probands: 21 in MTND subunit genes and 8 in mtDNA tRNA genes. Nuclear gene defects were inferred in 38% of probands based on cell hybrid studies, mtDNA sequencing, or mutation analysis. The most common clinical presentation was Leigh or Leigh-like disease in patients with either mtDNA or nuclear genetic defects. The median age at onset was later in mtDNA patients (12 months) compared to patients with a nuclear gene defect (3 months), although there was considerable overlap. The report confirmed that pathogenic mtDNA mutations are a significant cause of complex I deficiency in children.

Animal Model

The laboratory of Scheffler (DeFrancesco et al., 1976; Ditta et al., 1976; Breen and Scheffler, 1979; Soderberg et al., 1979) described several respiration-deficient mutants of Chinese hamster cells in culture. All depended on an ample supply of glucose in the medium to sustain a high rate of glycolysis. When galactose was substituted for glucose, the mutants died. This property was used to sort about 3 dozen mutants into 7 complementation groups (Soderberg et al., 1979). Whitfield et al. (1981) and Maiti et al. (1981) also identified gal-minus mutants in Chinese hamster cells that had a defect in the electron-transport chain. Specifically, several of the complementation groups appeared to be defective in complex I of the electron transport chain. Day and Scheffler (1982) reported that some of these complementation groups were X-linked in the hamster and mouse. The gene locus (-i) was symbolized 'res.' At least one complementation group was found to be autosomal.

History

Land et al. (1981) gave a particularly good general review of what was known about the defect in the several mitochondrial myopathies: (1) defects in substrate utilization, as in carnitine deficiency, carnitine palmitoyltransferase deficiency, and defects in various components of the pyruvate dehydrogenase complex; (2) defects in the coupling of mitochondrial respiration to phosphorylation, as in Luft disease and mitochondrial ATPase deficiency; and (3) deficiencies in components of mitochondrial respiratory chain, such as nonheme iron protein, cytochrome oxidase, cytochrome b deficiency, or NADH-CoQ reductase.