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Phenotype and genotype variation in primary carnitine deficiency
Y Wang1, S H Korman, J Ye
1Division of Medical Genetics, Department of Pediatrics, Emory University, Atlanta, Georgia, USA.
Summary
Primary carnitine deficiency, caused by SLC22A5 gene mutations, shows diverse clinical presentations. Even identical mutations in the carnitine transporter gene can lead to varied symptoms in affected individuals.
Area of Science:
- Genetics
- Biochemistry
- Molecular Biology
Background:
- Primary carnitine deficiency is an inherited metabolic disorder affecting fatty acid oxidation.
- It results from defects in carnitine transport, primarily due to mutations in the SLC22A5 gene.
Observation:
- This study investigated four additional families with primary carnitine deficiency.
- Novel mutations in the SLC22A5 gene were identified, including missense and premature STOP codon-inducing mutations.
- Carnitine transport function was significantly impaired in cells expressing identified mutations.
Findings:
- Four new mutations (Y4X; dup 254-264, 133X; R19P; R399Q) were discovered in the SLC22A5 gene.
- The 133X mutation was recurrent in two unrelated European families.
- Identical R399Q mutations in homozygous patients within the same family led to distinct clinical phenotypes.
Implications:
- Genetic heterogeneity in SLC22A5 mutations contributes to primary carnitine deficiency.
- Clinical variability exists even among individuals with the same SLC22A5 mutation, highlighting complex genotype-phenotype correlations.