RESUMO
Despite developments in targeted gene sequencing and whole-genome analysis techniques, the robust detection of all genetic variation, including structural variants, in and around genes of interest and in an allele-specific manner remains a challenge. Here we present targeted locus amplification (TLA), a strategy to selectively amplify and sequence entire genes on the basis of the crosslinking of physically proximal sequences. We show that, unlike other targeted re-sequencing methods, TLA works without detailed prior locus information, as one or a few primer pairs are sufficient for sequencing tens to hundreds of kilobases of surrounding DNA. This enables robust detection of single nucleotide variants, structural variants and gene fusions in clinically relevant genes, including BRCA1 and BRCA2, and enables haplotyping. We show that TLA can also be used to uncover insertion sites and sequences of integrated transgenes and viruses. TLA therefore promises to be a useful method in genetic research and diagnostics when comprehensive or allele-specific genetic information is needed.
Assuntos
Genômica/métodos , Haplótipos/genética , Modelos Genéticos , Técnicas de Amplificação de Ácido Nucleico/métodos , Análise de Sequência de DNA/métodos , Fusão Gênica/genética , Genes BRCA1 , Genes BRCA2 , Loci Gênicos/genética , Humanos , Neoplasias/genética , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Interstitial deletions of the chromosome 22q11.2 region are the most common microdeletions in humans. The TBX1 gene is considered to be the major candidate gene for the main features in 22q11.2 deletion syndrome, including congenital heart malformations, (para)thyroid hypoplasia, and craniofacial abnormalities. We report on eight patients with atypical deletions of chromosome 22q11.2. These deletions comprise the distal part of the common 22q11.2 deleted region but do not encompass the TBX1 gene. Ten similar patients with overlapping distal 22q11.2 deletions have been reported previously. The clinical features of these patients are described and compared to those found in the classic 22q11.2 deletion syndrome. We discuss the possible roles of a position effect or haploinsufficiency of distally located genes (e.g., CRKL) in the molecular pathogenesis of the 22q11.2 deletion syndrome.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 22/genética , Síndrome de DiGeorge/patologia , Proteínas com Domínio T/genética , Adolescente , Adulto , Pré-Escolar , Anormalidades Craniofaciais/genética , Anormalidades Craniofaciais/patologia , Síndrome de DiGeorge/genética , Feminino , Humanos , Recém-Nascido , Masculino , Fenótipo , GravidezRESUMO
Cat eye syndrome (CES) is caused by a gain of the proximal part of chromosome 22. Usually, a supernumerary marker chromosome is present, containing two extra copies of the chromosome 22q11.1q11.21 region. More sporadically, the gain is present intrachromosomally. The critical region for CES is currently estimated to be about 2.1 Mb and to contain at least 14 RefSeq genes. Gain of this region may cause ocular coloboma, preauricular, anorectal, urogenital and congenital heart malformations. We describe a family in which a 600 kb intrachromosomal triplication is present in at least three generations. The copy number alteration was detected using MLPA and further characterized with interphase and metaphase FISH and SNP-array. The amplified fragment is located in the distal part of the CES region. The family members show anal atresia and preauricular tags or pits, matching part of the phenotype of this syndrome. This finding suggests that amplification of the genes CECR2, SLC25A18 and ATP6V1E1, mapping within the critical region for CES, may be responsible for anorectal, renal and preauricular anomalies in patients with CES.