Carboxypeptidase A6 gene (CPA6) mutations in a recessive familial form of febrile seizures and temporal lobe epilepsy and in sporadic temporal lobe epilepsy

Annick Salzmann, Michel Guipponi, Peter J. Lyons, Lloyd D. Fricker, Matthew Sapio, Carmen Lambercy, Catherine Buresi, Bouchra Ouled Amar Bencheikh, Fatiha Lahjouji, Reda Ouazzani, Arielle Crespel, Denys Chaigne, Alain Malafosse

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Febrile seizures (FS) and temporal lobe epilepsy (TLE) were found in four of the seven siblings born to healthy Moroccan consanguineous parents. We hypothesized autosomal recessive (AR) inheritance. Combined linkage analysis and autozygosity mapping of a genome-wide single nucleotide polymorphism genotyping identified a unique identical by descent (IBD) locus of 9.6 Mb on human chromosome 8q12.1-q13.2. Sequencing of the 38 genes mapped within the linked interval revealed a homozygous missense mutation c.809C>T (p.Ala270Val) in the carboxypeptidase A6 gene (CPA6). Screening all exons of CPA6 in unrelated patients with partial epilepsy (n = 195) and FS (n = 145) revealed a new heterozygous missense mutation c.799G>A (p.Gly267Arg) in three TLE patients. Structural modeling of CPA6 indicated that both mutations are located near the enzyme's active site. In contrast to wild-type CPA6, which is secreted and binds to the extracellular matrix where it is enzymatically active, Ala270Val CPA6 was secreted at about 40% of the level of the wild-type CPA6 and was fully active, while Gly267Arg CPA6 was not detected in the medium or extracellular matrix. This study suggests that CPA6 is genetically linked to an AR familial form of FS and TLE, and is associated with sporadic TLE cases.

Original languageEnglish (US)
Pages (from-to)124-135
Number of pages12
JournalHuman Mutation
Volume33
Issue number1
DOIs
StatePublished - Jan 2012

Fingerprint

Carboxypeptidases
Febrile Seizures
Temporal Lobe Epilepsy
Mutation
Genes
Missense Mutation
Extracellular Matrix
Partial Epilepsy
Chromosome Mapping
Human Chromosomes
Single Nucleotide Polymorphism
Siblings
Exons
Catalytic Domain
Parents

Keywords

  • Autosomal recessive
  • Autozygosity mapping
  • CPA6
  • Febrile seizures
  • Linkage analysis
  • Temporal lobe epilepsy

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Cite this

Carboxypeptidase A6 gene (CPA6) mutations in a recessive familial form of febrile seizures and temporal lobe epilepsy and in sporadic temporal lobe epilepsy. / Salzmann, Annick; Guipponi, Michel; Lyons, Peter J.; Fricker, Lloyd D.; Sapio, Matthew; Lambercy, Carmen; Buresi, Catherine; Bencheikh, Bouchra Ouled Amar; Lahjouji, Fatiha; Ouazzani, Reda; Crespel, Arielle; Chaigne, Denys; Malafosse, Alain.

In: Human Mutation, Vol. 33, No. 1, 01.2012, p. 124-135.

Research output: Contribution to journalArticle

Salzmann, A, Guipponi, M, Lyons, PJ, Fricker, LD, Sapio, M, Lambercy, C, Buresi, C, Bencheikh, BOA, Lahjouji, F, Ouazzani, R, Crespel, A, Chaigne, D & Malafosse, A 2012, 'Carboxypeptidase A6 gene (CPA6) mutations in a recessive familial form of febrile seizures and temporal lobe epilepsy and in sporadic temporal lobe epilepsy', Human Mutation, vol. 33, no. 1, pp. 124-135. https://doi.org/10.1002/humu.21613
Salzmann, Annick ; Guipponi, Michel ; Lyons, Peter J. ; Fricker, Lloyd D. ; Sapio, Matthew ; Lambercy, Carmen ; Buresi, Catherine ; Bencheikh, Bouchra Ouled Amar ; Lahjouji, Fatiha ; Ouazzani, Reda ; Crespel, Arielle ; Chaigne, Denys ; Malafosse, Alain. / Carboxypeptidase A6 gene (CPA6) mutations in a recessive familial form of febrile seizures and temporal lobe epilepsy and in sporadic temporal lobe epilepsy. In: Human Mutation. 2012 ; Vol. 33, No. 1. pp. 124-135.
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AU - Fricker, Lloyd D.

AU - Sapio, Matthew

AU - Lambercy, Carmen

AU - Buresi, Catherine

AU - Bencheikh, Bouchra Ouled Amar

AU - Lahjouji, Fatiha

AU - Ouazzani, Reda

AU - Crespel, Arielle

AU - Chaigne, Denys

AU - Malafosse, Alain

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N2 - Febrile seizures (FS) and temporal lobe epilepsy (TLE) were found in four of the seven siblings born to healthy Moroccan consanguineous parents. We hypothesized autosomal recessive (AR) inheritance. Combined linkage analysis and autozygosity mapping of a genome-wide single nucleotide polymorphism genotyping identified a unique identical by descent (IBD) locus of 9.6 Mb on human chromosome 8q12.1-q13.2. Sequencing of the 38 genes mapped within the linked interval revealed a homozygous missense mutation c.809C>T (p.Ala270Val) in the carboxypeptidase A6 gene (CPA6). Screening all exons of CPA6 in unrelated patients with partial epilepsy (n = 195) and FS (n = 145) revealed a new heterozygous missense mutation c.799G>A (p.Gly267Arg) in three TLE patients. Structural modeling of CPA6 indicated that both mutations are located near the enzyme's active site. In contrast to wild-type CPA6, which is secreted and binds to the extracellular matrix where it is enzymatically active, Ala270Val CPA6 was secreted at about 40% of the level of the wild-type CPA6 and was fully active, while Gly267Arg CPA6 was not detected in the medium or extracellular matrix. This study suggests that CPA6 is genetically linked to an AR familial form of FS and TLE, and is associated with sporadic TLE cases.

AB - Febrile seizures (FS) and temporal lobe epilepsy (TLE) were found in four of the seven siblings born to healthy Moroccan consanguineous parents. We hypothesized autosomal recessive (AR) inheritance. Combined linkage analysis and autozygosity mapping of a genome-wide single nucleotide polymorphism genotyping identified a unique identical by descent (IBD) locus of 9.6 Mb on human chromosome 8q12.1-q13.2. Sequencing of the 38 genes mapped within the linked interval revealed a homozygous missense mutation c.809C>T (p.Ala270Val) in the carboxypeptidase A6 gene (CPA6). Screening all exons of CPA6 in unrelated patients with partial epilepsy (n = 195) and FS (n = 145) revealed a new heterozygous missense mutation c.799G>A (p.Gly267Arg) in three TLE patients. Structural modeling of CPA6 indicated that both mutations are located near the enzyme's active site. In contrast to wild-type CPA6, which is secreted and binds to the extracellular matrix where it is enzymatically active, Ala270Val CPA6 was secreted at about 40% of the level of the wild-type CPA6 and was fully active, while Gly267Arg CPA6 was not detected in the medium or extracellular matrix. This study suggests that CPA6 is genetically linked to an AR familial form of FS and TLE, and is associated with sporadic TLE cases.

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