Myopathy due to carnitine palmitoyltransferase II deficiency: updating genetic aspects of the first publication in Brazil.

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive inherited disorder related to lipid metabolism affecting skeletal muscle. The first cases of CPT II deficiency causing myopathy were reported in 1973. In 1983, Werneck et al published the first two Brazilian patients with myopathy due to CPT II deficiency, where the biochemical analysis confirmed deficient CPT activity in the muscle of both cases. Over the past 40 years since the pioneering publication, clinical phenotypes and genetic loci in the CPT2 gene have been described, and pathogenic mechanisms have been better elucidated. Genetic analysis of one of the original cases disclosed compound heterozygous pathogenic variants (p.Ser113Leu/p.Pro50His) in the CPT2 gene. Our report highlights the historical aspects of the first Brazilian publication of the myopathic form of CPT II deficiency and updates the genetic background of this pioneering publication.

Deficiência de carnitina palmitoiltransferase II (CPT II) é uma desordem de herança autossômica recessiva relacionada com o metabolismo do lipídio afetando músculo esquelético. Os primeiros dois casos de deficiência de CPT II causando miopatia foram relatados em 1973. Em 1983, Werneck et al. publicaram os primeiros pacientes brasileiros com miopatia por deficiência de CPT II, nos quais a análise bioquímica confirmou a atividade deficiente da CPT nos músculos em ambos os casos. Após 40 anos desde a publicação pioneira, fenótipos clínicos e loci genético no gene CPT2 foram descritos, bem com os mecanismos patológicos foram melhor elucidados. A análise genética de um dos casos da publicação original apresentou variantes patogênicas em heterozigose composta (p.Ser113Leu/p.Pro50His) no gene CPT2. O nosso relato destaca os aspectos históricos da primeira publicação brasileira da forma miopática da deficiência de CPT II e atualiza as bases genéticas dessa publicação pioneira.

Carnitine palmitoyltransferase type 2 deficiency: novel mutation in a Native South American family with whole-body muscle magnetic resonance imaging findings: two case reports.

BACKGROUND: The myopathic form of carnitine palmitoyltransferase type II deficiency is an inherited autosomal recessive metabolic myopathy usually starting in childhood. Most reports have been on European and Japanese populations, and no Native South American patients have been reported to date. The p.Ser113Leu mutation is the most frequent in the European population. Only lower-leg magnetic resonance imaging findings have been reported, with gluteus maximus involvement in one case and normal imaging in other patients. CASE PRESENTATION: Two Native South American siblings, a boy and a girl, presented to our neuromuscular clinic with recurrent rhabdomyolysis associated with transient muscle weakness after prolonged exercise. During episodes, their creatine kinase concentrations were markedly increased, up to 148,000 (1.48 × 105) IU/L in the boy and 18,000 (1.8 × 104) IU/L in the girl. The results of electroneuromyography and histopathology suggested a nonspecific myopathy. CPT2 gene sequencing showed two heterozygous mutations: the p.Ser113Leu variant and a novel one (predicted to be deleterious by in silico analysis), the p.Ser373Pro variant. The patients' parents were asymptomatic carriers. Whole-body magnetic resonance imaging showed mild selective involvement in the thoracic extensors and pelvic girdle in both siblings, and in the thighs and lower legs in one of them. Dietary and bezafibrate treatment was started, and symptomatic relief was observed. CONCLUSIONS: To the best of our knowledge, this is the first reported Native South American family with a CPT2 deficiency carrying a novel mutation and particular features visualized by whole-body magnetic resonance imaging.

Carrier frequency of a common mutation of carnitine palmitoyltransferase 1A deficiency and long-term follow-up in Finland.

OBJECTIVE: To assess the long-term clinical course of carnitine palmitoyltransferase 1A (CPT1A) deficiency, caused by the c.1364A>C (p.K455T) mutation, and the carrier frequency of this mutation in Finland. STUDY DESIGN: This was a long-term follow-up of patients in whom the common mutation was detected. RESULTS: Between 1999 and 2010, 6 cases of CPT1A deficiency were diagnosed and treated with a high-carbohydrate, low-fat diet. The patients experienced their first symptoms during the first years of life, provoked by viral illness and/or fasting. The clinical features included hypoketotic hypoglycemia, hepatopathy, and loss of consciousness, ranging from transient unconsciousness to prolonged hyperlipidemic coma. Five cases carried a homozygous c.1364A>C (p.K455T) mutation, whereas 1 case had a compound c.1364A>C/c.1493A>C (p.Y498S) mutation. During dietary therapy, the patients had few transient decompensations. No carriers of mutation c.1364A>C were detected by minisequencing of 150 control samples. CONCLUSION: Even though CPT1A deficiency may be life-threatening and lead to prolonged coma, the long-term prognosis is good. A genotype-phenotype correlation implies that the mutations detected are disease-causing. Despite Finland's location close to the Arctic polar region, the carrier frequency of the c.1364A>C mutation in Finland is far lower than that of the variants found in Alaskan, Canadian, and Greenland native populations.

Prevalence and distribution of the c.1436C→T sequence variant of carnitine palmitoyltransferase 1A among Alaska Native infants.

OBJECTIVES: To use genotype analysis to determine the prevalence of the c.1436C→T sequence variant in carnitine palmitoyltransferase 1A (CPT1A) among Alaskan infants, and evaluate the sensitivity of newborn screening by tandem mass spectrometry (MS/MS) to identify homozygous infants. STUDY DESIGN: We compared MS/MS and DNA analyses of 2409 newborn blood spots collected over 3 consecutive months. RESULTS: Of 2409 infants, 166 (6.9%) were homozygous for the variant, all but one of whom were of Alaska Native race. None of the homozygous infants was identified by MS/MS on the first newborn screen using a C0/C16 + C18 cutoff of 130. Among 633 Alaska Native infants, 165 (26.1%) were homozygous and 218 (34.4%) were heterozygous for the variant. The prevalence was highest in Alaska's northern/western regions (51.2% of 255 infants homozygous; allele frequency, 0.7). CONCLUSIONS: The CPT1A c.1436C→T variant is prevalent among some Alaska Native peoples, but newborn screening using current MS/MS cutoffs is not an effective means to identify homozygous infants. The clinical consequences of the partial CPT1A deficiency associated with this variant are unknown. If effects are substantial, revision of newborn screening, including Alaska-specific MS/MS cutoffs and confirmatory genotyping, may be needed.

Lethal neonatal and severe late infantile forms of carnitine palmitoyltransferase II deficiency associated with compound heterozygosity for different protein truncation mutations.

We describe a lethal neonatal form of carnitine palmitoyltransferase II (CPT II) deficiency with compound heterozygosity for 2 truncation mutations (Q413fs and 109AGC --> GCAGC). A new phenotype for a severe late infantile form of CPT II deficiency with hypoglycemia is associated with compound heterozygosity for the severe Q413fs mutation and a mild point mutation (P50H).

[Respiratory and renal dysfunctions due to lipid storage metabolic myopathy: case report]. / Insuficiências respiratória e renal desencadeadas por miopatia metabólica por acúmulo de lipídios: relato de caso.

We report a case of a 26-years old male patient with rhabdomyolisis with myoglobinuria associated with acute renal and respiratory failure, that occurred three days after upper airway infection. In the clinical and laboratory investigation of the patient, including electromyography and muscular biopsy, the diagnostic lead to a metabolic myopathy due to an enzymatic deficiency related to a disorder of lipid metabolism. The patient improved successfully with institution of advanced life support, including ventilatory assistance, dialysis, dietary adjust and L-carnitine reposition.

Lethal neonatal deficiency of carnitine palmitoyltransferase II associated with dysgenesis of the brain and kidneys.

We describe neonatal onset of a lethal multiorgan deficiency of carnitine palmitoyltransferase II (CPT II) associated with dysmorphic features, cardiomyopathy, and cystic dysplasia of the brain and kidneys. Concentrations of long-chain acylcarnitines were evaluated in blood and multiple tissues, diffuse lipid accumulation was present at autopsy, and a profound deficiency of CPT II activity was evident in heart, liver, muscle, and kidney tissue. This disorder constitutes another recognizable malformation syndrome with a metabolic basis. Deficiency of CPT II should be included in the differential diagnosis of patients with cystic renal dysplasia, dysmorphism, central nervous system malformations, and early death, along with glutaric acidemia type II, Zellweger syndrome, and other disorders in which peroxisomal beta-oxidation is impaired. The clinicopathologic similarities among these disorders raise the possibility that a common biochemical mechanism, namely the disruption of beta-oxidation of fatty acids, is responsible for the abnormal organogenesis.

Carnitine palmitoyltransferase II deficiency: a new cause of recurrent pancreatitis.

An 18-year-old female patient had a history of recurrent pancreatitis after prolonged periods of exercise coupled with a high-fat diet at the ages of 12 and 15 years. After the onset of recurrent myoglobinuria when she was 16 years old, deficiency of carnitine palmitoyltransferase type II (32% residual activity) was diagnosed on the basis of cultured skin fibroblasts. We conclude that deficiency of carnitine palmitoyltransferase type II may be a cause of pancreatitis and should be considered in the differential diagnosis, even in the absence of overt myoglobinuria.

Recurrent metabolic decompensation in profound carnitine palmitoyltransferase II deficiency.

A 3-year-old boy had recurrent episodes of lethargy, encephalopathy, and hepatomegaly accompanied by hypoglycemia, elevated liver aminotransferase and creatine kinase values, and nonketotic dicarboxylic aciduria; the serum carnitine level was moderately reduced. Carnitine palmitoyltransferase II activity was decreased in lymphocytes and fibroblasts. Therapy with L-carnitine and a diet low in long-chain triglycerides did not prevent recurrent episodes.

Atypical features of the hepatic form of carnitine palmitoyltransferase deficiency in a Hutterite family.

We describe hepatic carnitine palmitoyltransferase (CPT I) deficiency in three children (a brother and sister and their second cousin) from an extended inbred Hutterite kindred. The patients were first seen between 8 and 18 months of age with recurrent episodes of hypoketotic hypoglycemia accompanied by a decreased level of consciousness and hepatomegaly. One patient had two Reye syndrome-like episodes. Abnormal organic acids were rarely detected in urine. Serum total and free carnitine levels were elevated in all three patients. Fibroblast acyl-coenzyme A dehydrogenase activities were normal in all, but palmitic acid oxidation, performed in fibroblasts from one patient, was less than 10% of control values. Activity of CPT I in cultured skin fibroblasts from the three patients was 10% to 15% of control levels; CPT II activity was normal. Activity of CPT I and CPT II in muscle from one patient was normal. Atypical features in two of these patients were greatly elevated levels of liver enzymes and creatine kinase during acute episodes. The patients have recently been successfully treated with medium-chain triglycerides and avoidance of fasting. Early identification and treatment of this disorder may avert potentially fatal episodes of hypoglycemia.

[Myopathy due to carnitine palmitoyltransferase deficiency. Report of 2 cases with enzymatic analyses on muscle tissue]. / Miopatia por deficiência de carnitina-palmitil-transferase. Relato de 2 casos com dosagens enzimáticas no tecido muscular.

We describe two brothers, 25 and 19 years-old, with muscle pain and decreased strength after prolonged exercise; these symptoms are worsened by cold whether of fasting. One of the patients developed recurrent myoglobinuria and had one episode of renal failure. Laboratory investigations were normal between the crises, but during myoglobinuria, serum creatine kinase activity increased 100 times. Electromyography was suggestive of denervation. Muscle biopsy showed increased lipid droplets by the "oil red O" stain and increased activity of succinic dehydrogenase histochemical reaction. Lactate production during ischemia was normal. Biochemical analysis showed decreased carnitine-palmityl-transferase activity in muscle (7.23 and 10.58 nmoles/min/gr; normal range 66.7 +/- 17.3), with normal values for carnitine-octanoyl-transferase and carnitine-acetyl-transferase. The metabolic pathway of fatty acid utilization as an energy source for muscle during exercise in normal and in pathological conditions is discussed.

Fasting hypoglycemia resulting from hepatic carnitine palmitoyl transferase deficiency.

Two sisters developed severe hypoglycemia at 8 months of age, resulting in death in one of them. Metabolic studies of the second revealed decline of blood glucose concentration and low plasma ketone body values during a 20-hour fast, both reversed by administration of medium-chain triglycerides. Carnitine palmitoyl transferase activity was absent in the liver extract of the patient; lack of this enzyme impairs long-chain fatty acid oxidation and ketogenesis. Failure of gluconeogenesis could result from decreased production of acetyl-CoA and NADH.

Recurrent myoglobinuria and muscle carnitine palmityltransferase deficiency.

A 16-year-old boy with a two-year history of recurrent attacks of myalgia, muscle cramps without weakness, and myoglobinuria was shown to have a deficiency in muscle carnitine palmityltransferase. Serum concentrations of creatinine phosphokinase, serum glutamic oxalacetic transaminase, and aldolase were elevated. An electromyogram was consistent with a nonspecific myopathy as were microscopic and ultrastructural examinations of biopsied muscle. Venous lactic acid response to ischemic exercise was compatible with paroxysmal idiopathic myoglobinuria. Activities of muscle phosphorylase A and B, phosphofructokinase, muscle palmityl CoA synthetase, carnitine, and serum carnitine were normal as was the glycogen content. Activity of muscle carnitine palmityltransferase (2.7 microM/minute/mg protein), as measured by a spectrophotometric method and by radioactive assay, was significantly reduced when compared to normal control subjects (14.5 microM/minute/mg protein) and ischemic control subjects (13.8 microM/minute/mg protein). Muscle carnitine acetyltransferase (13.4 microM/minute/mg protein) was approximately 50% of normal control values (25.5 microM/minute/mg protein). This is the third reported case of myoglobinuria in a patient associated with a deficiency of muscle carnitine palmityltransferase activity.