Interpreting the clinical significance of combined variants in multiple recessive disease genes: systematic investigation of Joubert syndrome yields little support for oligogenicity.
Genet Med
; 20(2): 223-233, 2018 Feb.
Article
em En
| MEDLINE
| ID: mdl-28771248
ABSTRACT
PurposeNext-generation sequencing (NGS) often identifies multiple rare predicted-deleterious variants (RDVs) in different genes associated with a recessive disorder in a given patient. Such variants have been proposed to contribute to digenicity/oligogenicity or "triallelism" or to act as genetic modifiers.MethodsUsing the recessive ciliopathy Joubert syndrome (JBTS) as a model, we investigated these possibilities systematically, relying on NGS of known JBTS genes in a large JBTS and two control cohorts.Results65% of affected individuals had a recessive genetic cause, while 4.9% were candidates for di-/oligogenicity, harboring heterozygous RDVs in two or more genes, compared with 4.2-8% in controls (P = 0.66-0.21). Based on Exome Aggregation Consortium (ExAC) allele frequencies, the probability of cumulating RDVs in any two JBTS genes is 9.3%. We found no support for triallelism, as no unaffected siblings carried the same biallelic RDVs as their affected relative. Sixty percent of individuals sharing identical causal RDVs displayed phenotypic discordance. Although 38% of affected individuals harbored RDVs in addition to the causal mutations, their presence did not correlate with phenotypic severity.ConclusionOur data offer little support for triallelism or digenicity/oligogenicity as clinically relevant inheritance modes in JBTS. While phenotypic discordance supports the existence of genetic modifiers, identifying clinically relevant modifiers remains challenging.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Variação Genética
/
Predisposição Genética para Doença
/
Estudos de Associação Genética
/
Genes Recessivos
/
Doenças Genéticas Inatas
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article