Looking beyond the exome: a phenotype-first approach to molecular diagnostic resolution in rare and undiagnosed diseases.
Genet Med
; 20(4): 464-469, 2018 04.
Article
em En
| MEDLINE
| ID: mdl-28914269
ABSTRACT
PurposeTo describe examples of missed pathogenic variants on whole-exome sequencing (WES) and the importance of deep phenotyping for further diagnostic testing.MethodsGuided by phenotypic information, three children with negative WES underwent targeted single-gene testing.ResultsIndividual 1 had a clinical diagnosis consistent with infantile systemic hyalinosis, although WES and a next-generation sequencing (NGS)-based ANTXR2 test were negative. Sanger sequencing of ANTXR2 revealed a homozygous single base pair insertion, previously missed by the WES variant caller software. Individual 2 had neurodevelopmental regression and cerebellar atrophy, with no diagnosis on WES. New clinical findings prompted Sanger sequencing and copy number testing of PLA2G6. A novel homozygous deletion of the noncoding exon 1 (not included in the WES capture kit) was detected, with extension into the promoter, confirming the clinical suspicion of infantile neuroaxonal dystrophy. Individual 3 had progressive ataxia, spasticity, and magnetic resonance image changes of vanishing white matter leukoencephalopathy. An NGS leukodystrophy gene panel and WES showed a heterozygous pathogenic variant in EIF2B5; no deletions/duplications were detected. Sanger sequencing of EIF2B5 showed a frameshift indel, probably missed owing to failure of alignment.ConclusionThese cases illustrate potential pitfalls of WES/NGS testing and the importance of phenotype-guided molecular testing in yielding diagnoses.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Predisposição Genética para Doença
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Técnicas de Diagnóstico Molecular
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Estudos de Associação Genética
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Exoma
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
Limite:
Child
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Child, preschool
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Female
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Humans
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Infant
Idioma:
En
Revista:
Genet Med
Assunto da revista:
GENETICA MEDICA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos