Organization of the human liver carnitine palmitoyltransferase 1 gene (CPT1A) and identification of novel mutations in hypoketotic hypoglycaemia

Abstract

Carnitine palmitoyltransferase 1A (CPT1A) deficiency is a rare autosomal recessive disorder of mitochondrial fatty acid oxidation. CPT1 controls the import of long-chain fatty acids into the mitochondria, where they are oxidized. Two CPT1 isoforms, the so-called "liver" and "muscle" CPT1s encoded by the CPT1Aand CPT1Bgenes, respectively, have been identified so far. While the cDNA sequences of both isoforms are known, only CPT1Bgene organization has yet been described. We took advantage of the working draft data to characterize the organization of the human CPT1A gene. We have shown the existence of 20 exons, spanning 60 kb of DNA. Two alternate promoters and numerous transcription factor-binding sites were identified within the 5' upstream region of the gene. In the 3' untranslated region, the major polyA signal was suggested to lie about 2 kb downstream of the stop codon. These data enabled us to characterize six novel mutations in four CPT1A-deficient patients; namely Q100X (exon 4), A414 V (exon 11), Y498C (exon 13), 1876-1G>A (intron 15), a 113-bp intronic insertion in the mature CPT1A mRNA (exon 13-14 junction), and a large 8-kb deletion encompassing intron 14 to exon 17. Thus, identification of the CPT1A gene organization contributes to improve the molecular screening in patients and provides tools for the study of the human CPT1A gene expression.

Alternative Exon Usage in the Single CPT1 Gene of Drosophila Generates Functional Diversity in the Kinetic Properties of the Enzyme

“…Alignment of these alternative ends with the complete gene sequence that has since been published has now confirmed this. As in the case of the mammalian CPT1A (35,36) and CPT1B promoters (37)(38)(39)(40), those for DmCPT1 are TATAless. Both promoter regions of the D. melanogaster CPT1 contain a number of sequence motifs with a high degree of similarity to known transcription factor-binding sites.…”

Correlation between genotype, metabolic data, and clinical presentation in carnitine palmitoyltransferase 2 (CPT2) deficiency

“…While CPT1 exists as at least two distinct isoforms, the so-called ''liver'' (CPT1A; MIM# 600528) and ''muscle'' (CPT1B; MIM# 601987) CPT1 [Tein et al, 1989;Britton et al, 1995;Esser et al, 1996;Yamazaki et al, 1996], CPT2 (MIM# 600650) has been demonstrated to be ubiquitous [Woeltje et al, 1990;Demaugre et al, 1990]. In humans, the cDNA sequence [Britton et al, 1995;Yamazaki et al, 1996;Finocchiaro et al, 1991] and the gene organization [Gobin et al, 2002;Yamazaki et al, 1997;Verderio et al, 1995] of CPT1A, CPT1B, and CPT2 have been reported.…”

Functional and Structural Basis of Carnitine Palmitoyltransferase 1A Deficiency

“…Fibroblasts-As previously reported, three missense mutations were identified in patient 1: A275T and A414V carried on the paternal allele, and Y498C carried on the maternal allele (27). The present molecular analysis of patient 2 permitted to identify both the heterozygous 2126GϾA substitution predictive of the G709E mutation, and the 948delG deletion, which corresponds to the R316fsX328 frameshift at codon 316 (exon 9) generating a stop signal 12 codons downstream (exon 10) (Fig.…”

“…Case report of patient 2 (29) as well as molecular analysis of patients 1 and 3 (26,27) have previously been reported. Fibroblasts from controls and patients were cultured as previously described (30) and were used to extract DNA according to standard methods and RNA using RNeasy Midi kit (Qiagen).…”

“…Fibroblasts from controls and patients were cultured as previously described (30) and were used to extract DNA according to standard methods and RNA using RNeasy Midi kit (Qiagen). Mutation analysis of patient 2 was performed at both cDNA and gDNA levels by sequencing approach, as previously described (26,27).…”