title: Molecular analysis of the SMN1 and NAIP genes in 60 Tunisian spinal muscular atrophy patients.
abstract: In this study we examined the deletion of SMN and NAIP genes in 60 Tunisian families. There were 35 patients with type I SMA. 18 with type II SMA. 6 with type III SMA and I with type IV SMA. The age of onset was before 6 months for type I, between 6 months and 2 years for type II, between 2 years and 17 years for type III and 30 years for type IV. Exon 7 of SMNI gene was homozygously deleted in 95% (57/60) of SMA patients. There was a higher frequency of homozygous absence of SMN1 in type I and type II (100% and 94% respectively) than in type III (66,7%). SMN1 exon 8 was undetectable in 88% (53/60) of patients. The case type II patient with homozygous deletion of SMNI exon 7 and not exon 8 was tested for the presence of a hybrid SMN gene. This patient showed in the second PCR a SMN1 exon 8 product by restriction site assay indicating that a gene conversion event had occurred. All parents' individuals retained one copy of their SMN1 gene. Exon 5 of NAIP gene was homozygously deleted in 58% (35/60) of patients (77% in type I (27/35), 27,7% in type II (5/18), 50% (3/6) in type III. No patient had a deletion in NAIP gene without a deletion in the SMN1 gene. Homozygous deletion of NAIP exon 5 was detected in 1 parent. Our results show that the incidence of NAIP deletion is higher in the more severe SMA cases.
authors.affiliation: Department of Human Genetics Charles, Nicolle Hospital, Tunis, Tunisia.
authors.forename: Ridha
authors.initials: R
authors.lastname: Mrad
authors.forename: Imen
authors.initials: I
authors.lastname: Dorboz
authors.forename: Lamia
authors.initials: L
authors.lastname: Ben Jemaa
authors.forename: Faouzi
authors.initials: F
authors.lastname: Maazoul
authors.forename: Madiha
authors.initials: M
authors.lastname: Trabelsi
authors.forename: Meriem
authors.initials: M
authors.lastname: Chaabouni
authors.forename: Brahim
authors.initials: B
authors.lastname: Mlaiki
authors.forename: Nakjoua
authors.initials: N
authors.lastname: Miladi
authors.forename: Faycel
authors.initials: F
authors.lastname: Hentati
authors.forename: Habiba
authors.initials: H
authors.lastname: Chaabouni
mesh_terms: D015331:Cohort Studies; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D005091:Exons; D017353:Gene Deletion; D006720:Homozygote; D006801:Humans; D009134:Muscular Atrophy, Spinal / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D051616:Neuronal Apoptosis-Inhibitory Protein / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein; D014416:Tunisia
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; C496800:NAIP protein, human; D009419:Nerve Tissue Proteins; D051616:Neuronal Apoptosis-Inhibitory Protein; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein