Dataset Information

Reliable Diagnosis of Carnitine Palmitoyltransferase Type IA Deficiency by Analysis of Plasma Acylcarnitine Profiles.

ABSTRACT: BACKGROUND:Carnitine palmitoyltransferase IA (CPT-IA) deficiency is an inherited disorder of the carnitine cycle (MIM #255120). Patients affected by this deficiency might be missed easily because of lack of specific and sensitive biochemical markers. In this study, sensitivity and specificity of plasma free carnitine (C0) and long-chain acylcarnitines (lc-ac: C16:0-, C16:1-, C18:0-, C18:1- and C18:2-ac) was evaluated, including the sum of lc-ac (?lc-ac) and the molar ratios C0/(C16:0-ac+C18:0-ac) and C0/?lc-ac. METHODS:Nine plasma acylcarnitine profiles of 4 CPT-IA deficient patients were compared with profiles of 2,190 subjects suspected of or diagnosed with an inherited disorder of metabolism. Age-dependent reference values were calculated based on the patient population without a definite diagnosis of an inborn error of metabolism (n?=?1,600). Sensitivity, specificity, and Receiver Operating Characteristic (ROC) curves were calculated based on samples of the whole patient population. RESULTS:Concentrations of C0 in plasma were normal in all CPT-IA deficient patient samples. ROC analyses showed highest diagnostic values for C18:0-ac, C18:1-ac, and ?lc-ac (AUC 1.000) and lowest for C0 (AUC 0.738). Combining two markers, i.e., a plasma C18:1-ac concentration <0.05 ?mol/L and a molar ratio of C0/(C16:0-ac+C18:0-ac) >587, specificity to diagnose CPT-IA deficiency increased to 99.3% compared with either C18:1-ac (97.4%) or C0/(C16:0-ac+C18:0-ac) (96.9%) alone, all at a sensitivity of 100%. CONCLUSIONS:Combination of a low concentration of C18:1-ac with a high molar ratio of C0/(C16:0-ac+C18:0-ac) ratio in plasma has high diagnostic value for CPT-IA deficiency. Patients with a clinical suspicion of CPT-IA deficiency can be diagnosed with this test combination.

SUBMITTER: Heiner-Fokkema MR

PROVIDER: S-EPMC5362552 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Reliable Diagnosis of Carnitine Palmitoyltransferase Type IA Deficiency by Analysis of Plasma Acylcarnitine Profiles.

Heiner-Fokkema M Rebecca MR Vaz Frédéric M FM Maatman Ronald R Kluijtmans Leo A J LA van Spronsen Francjan J FJ Reijngoud Dirk-Jan DJ

JIMD reports 20160614

<h4>Background</h4>Carnitine palmitoyltransferase IA (CPT-IA) deficiency is an inherited disorder of the carnitine cycle (MIM #255120). Patients affected by this deficiency might be missed easily because of lack of specific and sensitive biochemical markers. In this study, sensitivity and specificity of plasma free carnitine (C0) and long-chain acylcarnitines (lc-ac: C16:0-, C16:1-, C18:0-, C18:1- and C18:2-ac) was evaluated, including the sum of lc-ac (∑lc-ac) and the molar ratios C0/(C16:0-ac+ ...[more]

PMID: 27295194

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Project description:Carnitine palmitoyltransferase (CPT) catalyzes the transfer of long- and medium-chain fatty acids from cytoplasm into mitochondria, where oxidation of fatty acids takes place. Deficiency of CPT enzyme is associated with rare diseases of fatty acid metabolism. CPT is present in two subforms: CPT I at the outer mitochondrial membrane and carnitine palmitoyltransferase II (CPT II) inside the mitochondria. Deficiency of CPT II results in the most common inherited disorder of long-chain fatty acid oxidation affecting skeletal muscle. There is a lethal neonatal form, a severe infantile hepato-cardio-muscular form, and a rather mild myopathic form characterized by exercise-induced myalgia, weakness, and myoglobinuria. Total CPT activity (CPT I + CPT II) in muscles of CPT II-deficient patients is generally normal. Nevertheless, in some patients, not detectable to reduced total activities are also reported. CPT II protein is also shown in normal concentration in patients with normal CPT enzymatic activity. However, residual CPT II shows abnormal inhibition sensitivity towards malonyl-CoA, Triton X-100 and fatty acid metabolites in patients. Genetic studies have identified a common p.Ser113Leu mutation in the muscle form along with around 100 different rare mutations. The biochemical consequences of these mutations have been controversial. Hypotheses include lack of enzymatically active protein, partial enzyme deficiency and abnormally regulated enzyme. The recombinant enzyme experiments that we recently conducted have shown that CPT II enzyme is extremely thermoliable and is abnormally inhibited by different emulsifiers and detergents such as malonyl-CoA, palmitoyl-CoA, palmitoylcarnitine, Tween 20 and Triton X-100. Here, we present a conceptual overview on CPT II deficiency based on our own findings and on results from other studies addressing clinical, biochemical, histological, immunohistological and genetic aspects, as well as recent advancements in diagnosis and therapeutic strategies in this disorder.

Dataset Information

Reliable Diagnosis of Carnitine Palmitoyltransferase Type IA Deficiency by Analysis of Plasma Acylcarnitine Profiles.

Publications

Reliable Diagnosis of Carnitine Palmitoyltransferase Type IA Deficiency by Analysis of Plasma Acylcarnitine Profiles.

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