Infant onset subacute necrotizing encephalomyelopathy (Leigh's disease)

The molecular and cellular basis of copper dysregulation and its relationship with human pathologies

Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu⁺ -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in carcinogenesis as a promotor of tumor growth and an inducer of redox stress in cancer cells. Cu also plays role in cancer treatment as a component of drugs and a regulator of drug sensitivity and uptake. In this review, we provide an overview of the current knowledge of Cu metabolism and transport and its relation to various human pathologies.

Leigh syndrome associated with West syndrome

Leigh syndrome (LS) (sub-acute necrotizing encephalomyelopathy) is characterized by symmetric brain lesions occurring mainly in the basal ganglia and associated with variable clinical manifestations such as hypotonia, psychomotor retardation, and feeding difficulties. Patients with LS may develop seizures. Only three patients with LS have been identified in the literature as having West syndrome (WS). We have seen 12 children with LS in the past 20 years, and noticed that as many as five of them developed WS. This report discusses five LS children with WS, comparing them with seven LS children without WS. In all five patients, infantile spasms developed after LS had become evident, in addition to other type(s) of seizures. The onset of LS in all the patients with WS was before 10 months of age. Although not statistically proven, early onset of LS, spasticity, nystagmus, apnea, poor feeding, and cardiac problems seemed to be associated with the development of WS. We were not able to conclude that certain types of symptoms or examination results of patients with LS indicated the development of WS. The association of LS with WS did not markedly influence the prognoses of the children. WS may not be a rare complication of LS, especially in infants under 12 months of age. This report is the first review of LS associated with WS.

Measurement of lactate in cerebrospinal fluid in investigation of inherited metabolic disease

Measurement of lactate concentrations in cerebrospinal fluid (CSF) has been suggested as part of the investigation of inborn errors of the electron transport chain, but little information exists regarding the reference range in children or the relationship between CSF and plasma concentrations. In 39 children without bacterial meningitis, diabetes, or recent seizures, we determined that the median (range) lactate concentrations in CSF and plasma collected concurrently were 1.4 (0.8–2.2) and 1.5 (0.6–2.3) mmol/L; the regression equation was CSF lactate = (0.38 ± 0.06) plasma lactate + 0.83 (r2 = 0.14). In 8 of 11 (73%) children with electron transport chain defects, CSF lactate was ≥3.0 mmol/L; however, 2 of these 8 had a normal plasma lactate concentration. CSF lactate was also increased in 2 children with nonketotic hyperglycinemia. The finding that CSF lactate concentrations may be increased despite a normal plasma lactate value in children with electron transport chain defects is an important clue to the diagnosis of these disorders.

Leigh syndrome: clinical features and biochemical and DNA abnormalities

We investigated the etiology of Leigh syndrome in 67 Australian cases from 56 pedigrees, 35 with a firm diagnosis and 32 with some atypical features. Biochemical or DNA defects were determined in both groups, ie, 80% in the tightly defined group and 41% in the "Leigh-like" group. Eleven patients had mitochondrial DNA point mutations (nucleotide [nt] 8993 T to G, nt 8993 T to C, or nt 8344 A to G) and 1 Leigh-like patient had a heteroplasmic deletion. Twenty-nine patients had enzyme defects, ie, 13 respiratory chain complex I, 9 complex IV, and 7 pyruvate dehydrogenase complex (PDHC). Complex I deficiency is more common than recognized previously. Six PDHC-deficient patients had mutations in the X-chromosomal gene encoding the E1alpha subunit of PDHC. Parental consanguinity suggested autosomal recessive inheritance in two complex IV-deficient sibships. We found no strong correlation between the clinical features and basic defects. An assumption of autosomal recessive inheritance (frequently made in the past) would have been wrong in nearly one-half (11 of 28 tightly defined and 18 of 41 total patients) of those in whom a cause was found. A specific defect must be identified if reliable genetic counseling is to be provided.

Connatal Leigh disease

Two children are described with pathology-proven Leigh disease. Rather than the typical degenerative course with loss of acquired development, they presented with a static encephalopathy manifested by seizures from birth and failure to acquire any milestones. A similar connatal presentation has been reported in other degenerative disorders, such as Pelizaeus-Merzbacher disease. Heredodegenerative disorders should be considered when no cause is discovered for a severe, congenital, static encephalopathy.