Thermo-sensitive mitochondrial trifunctional protein deficiency presenting with episodic myopathy.
J Inherit Metab Dis
; 45(4): 819-831, 2022 07.
Article
en En
| MEDLINE
| ID: mdl-35403730
ABSTRACT
Mitochondrial trifunctional protein (MTP) is involved in long-chain fatty acid ß-oxidation (lcFAO). Deficiency of one or more of the enzyme activities as catalyzed by MTP causes generalized MTP deficiency (MTPD), long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), or long-chain ketoacyl-CoA thiolase deficiency (LCKATD). When genetic variants result in thermo-sensitive enzymes, increased body temperature (e.g. fever) can reduce enzyme activity and be a risk factor for clinical decompensation. This is the first description of five patients with a thermo-sensitive MTP deficiency. Clinical and genetic information was obtained from clinical files. Measurement of LCHAD and LCKAT activities, lcFAO-flux studies and palmitate loading tests were performed in skin fibroblasts cultured at 37°C and 40°C. In all patients (four MTPD, one LCKATD), disease manifested during childhood (manifestation age 2-10 years) with myopathic symptoms triggered by fever or exercise. In four patients, signs of retinopathy or neuropathy were present. Plasma long-chain acylcarnitines were normal or slightly increased. HADHB variants were identified (at age 6-18 years) by whole exome sequencing or gene panel analyses. At 37°C, LCHAD and LCKAT activities were mildly impaired and lcFAO-fluxes were normal. Remarkably, enzyme activities and lcFAO-fluxes were markedly diminished at 40°C. Preventive (dietary) measures improved symptoms for most. In conclusion, all patients with thermo-sensitive MTP deficiency had a long diagnostic trajectory and both genetic and enzymatic testing were required for diagnosis. The frequent absence of characteristic acylcarnitine abnormalities poses a risk for a diagnostic delay. Given the positive treatment effects, upfront genetic screening may be beneficial to enhance early recognition.
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Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Miopatías Mitocondriales
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Errores Innatos del Metabolismo Lipídico
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Enfermedades Musculares
Tipo de estudio:
Diagnostic_studies
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Prognostic_studies
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Risk_factors_studies
Límite:
Adolescent
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Child
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Child, preschool
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Humans
Idioma:
En
Revista:
J Inherit Metab Dis
Año:
2022
Tipo del documento:
Article
País de afiliación:
Países Bajos