Research Article
Combined Respiratory Chain Deficiency and UQCC2 Mutations in Neonatal Encephalomyopathy: Defective Supercomplex Assembly in Complex III Deficiencies
Table 2
Clinical features of complex III deficiencies.
| | Complex III subunits | Complex III assembly factors |
| Gene | MT-CYB | CYC1 | UQCRB | UQCRC2 | UQCRQ | UQCC2 | UQCC2 | UQCC3 | TTC19 | LYRM7 | BCS1L | MIM accession | 516020 | 615453 | 615158 | 615160 | 615159 | 615824 | 615824 | 616097 | 615157 | 615838 | 124000 | Number of patients | >50 | 1 | 1 | 4 | 25, 1 kindred | 1 | 1, this study | 1 | Ca. 15 | 9 | >30 | Onset | Childhood, adulthood | Infancy, early childhood | Late infancy | Neonatal | First months of life | Intrauterine | Intrauterine | Birth | Late infancy, adulthood | Infancy, 14 years | First years, infancy | Intrauterine growth retardation | | | | | | Yes | Yes | | | | | Hearing impairment | | | | | | Yes | n.a. | No | | | Yes | Hypotonia | Yes | | | | | Yes | Yes | Yes | | Yes | Yes | Seizures | | | | | | Yes | Yes | No | | | Yes | Abnormal EEG | | | | | | | Yes | | | | Yes | Metabolic crisis | | | Yes | | | | | Yes | | Yes | | Lactic acidosis | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | | Yes | Yes | Increased CSF lactate | Yes | | | | | Yes | | | | | | Hypoglycaemia | | Yes | Yes | Yes | | | | Yes | | | | Developmental disability | | No | No | No | | No | n.a. | Yes | Yes | Yes | Yes | Intellectual disability | | No | No | Yes (1)/no (1) | Yes | | n.a. | Yes | | Yes | Yes | Other features | | In one hyperammonemic liver failure | | | Extrapyramidal movement disorder, survival into thirties | Renal tubular acidosis, no information after 9 years of age | Status epilepticus, died at 33 days of life | Muscular weakness | Later regression with spasticity and movement disorder leading to minimal residual state | Deterioration after metabolic crises, specific MRI pattern (multifocal cavitating leukoencephalopathy) | Hepatopathy, renal involvement, often early death |
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