Large genomic mutations within the ATM gene detected by MLPA, including a duplication of 41 kb from exon 4 to 20.
Mutation detection remains problematic for large genes, primarily because PCR-based methodology fails to detect heterozygous deletions and any duplication. In the ATM gene only a handful of multi-exon deletions have been described to date, and this type of mutation has been considered rare. To address this issue we tested a new MLPA (Multiplex Ligation Probe Amplification) kit that covers 33 of the 66 ATM exons, using for controls two previously characterized genomic deletions in addition to three A-T patients, taken from a survey of nine, who had missing four mutations unidentified after conventional mutation screening. We identified for the first time: 1) a approximately 41 kb genomic duplication spanning exons 4-20 (c.-30_2816dup41kb)(a.k.a., ATM dup 41 kb); 2) a novel genomic deletion including exon 31, and 3) in hemizygosis a point mutation in the non-deleted exon 31. In this study we extended mutation detection to nine new Italian A-T patients, using a combined approach of haplotype analysis, DHPLC and MLPA. Overall we achieved a mutation detection rate of >97%, and can now define a spectrum of ATM mutations based on twenty-one consecutive Italian families with A-T.
Cavalieri
Simona
S
Department of Genetics, Biology and Biochemistry, University of Torino, S. Giovanni Battista Hospital, Torino, Italy.
Funaro
Ada
A
Pappi
Patrizia
P
Migone
Nicola
N
Gatti
Richard A
RA
Brusco
Alfredo
A
D064007:Ataxia Telangiectasia Mutated Proteins; D016022:Case-Control Studies; D018797:Cell Cycle Proteins / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D017353:Gene Deletion; D020440:Gene Duplication; D005819:Genetic Markers; D006239:Haplotypes; D006801:Humans; D009154:Mutation; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D010375:Pedigree; D017354:Point Mutation; D020641:Polymorphism, Single Nucleotide; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D020080:Tandem Repeat Sequences; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005819:Genetic Markers; D025521:Tumor Suppressor Proteins; D004247:DNA; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases