First characterization of a large deletion of the PDHA 1 gene.
Pyruvate dehydrogenase complex (PDC) deficiency is one of the major recognized causes of congenital lactic acidosis. The most common form is due to PDHA 1 gene (Xp22.12) defects. Here, we report the case of a Polynesian girl presenting with delayed neurological development, cortical atrophy, and posterior corpus callosum agenesis. Elevated lactate and pyruvate levels in blood and cerebrospinal fluid suggested PDC deficiency. However, PDC activity was within the normal range in lymphocytes and the direct sequencing of the 11 exons and intron-exon junctions of the PDHA 1 gene did not show any changes. Long-range PCR amplification of the whole gene (16 kb) from blood DNA revealed a heterozygous deletion of approximately 4.2kb. Fine mapping of the deletion breakpoint was achieved using purified long-range PCR products for restriction enzyme analysis and direct sequencing. The deletion removed a 4,227 bp region covering part of intron 5 to part of intron 9 [g.10,145_14,371 del 4,227]. The deletion breakpoint contained a short direct repeat (GTAG), which may be derived either from the upstream or the downstream homologous sequence. The presence of a GAG triplet and inverted repeats in the vicinity of the deletion suggest replication slippage at a polymerase alpha arrest site. This is the first time that a large intragenic deletion of the PDHA 1 gene has been characterized.
Brivet
Michèle
M
Laboratoire de Biochimie 1, AP-HP hôpital de Bicêtre, France. michele.brivet@bct.ap-hop-paris.fr
Moutard
Marie-Laure
ML
Zater
Mokhtar
M
Venet
Lydia
L
Chenel
Claude
C
Mine
Manuele
M
Legrand
A
A
D001483:Base Sequence; D002675:Child, Preschool; D004247:DNA / Q000235:genetics; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D007438:Introns; D016133:Polymerase Chain Reaction; D011114:Polynesia; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000235:genetics*; D015325:Pyruvate Dehydrogenase Complex Deficiency Disease / Q000201:enzymology* / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017384:Sequence Deletion
D004247:DNA; D030481:Pyruvate Dehydrogenase (Lipoamide); C065640:pyruvate dehydrogenase E1alpha subunit