RESUMO
Neurodevelopmental disorders (NDDs) affect more than 3% of children and are attributable to single-gene mutations at more than 1000 loci. Traditional methods yield molecular diagnoses in less than one-half of children with NDD. Whole-genome sequencing (WGS) and whole-exome sequencing (WES) can enable diagnosis of NDD, but their clinical and cost-effectiveness are unknown. One hundred families with 119 children affected by NDD received diagnostic WGS and/or WES of parent-child trios, wherein the sequencing approach was guided by acuity of illness. Forty-five percent received molecular diagnoses. An accelerated sequencing modality, rapid WGS, yielded diagnoses in 73% of families with acutely ill children (11 of 15). Forty percent of families with children with nonacute NDD, followed in ambulatory care clinics (34 of 85), received diagnoses: 33 by WES and 1 by staged WES then WGS. The cost of prior negative tests in the nonacute patients was $19,100 per family, suggesting sequencing to be cost-effective at up to $7640 per family. A change in clinical care or impression of the pathophysiology was reported in 49% of newly diagnosed families. If WES or WGS had been performed at symptom onset, genomic diagnoses may have been made 77 months earlier than occurred in this study. It is suggested that initial diagnostic evaluation of children with NDD should include trio WGS or WES, with extension of accelerated sequencing modalities to high-acuity patients.
Assuntos
Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/genética , Exoma , Genoma , Sequência de Bases , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Predisposição Genética para Doença , Genoma Humano , Custos de Cuidados de Saúde , Humanos , Lactente , Masculino , Técnicas de Diagnóstico Molecular/métodos , Mutação , Fenótipo , Análise de Sequência de DNA/métodosRESUMO
Orphan diseases are individually uncommon but collectively contribute significantly to pediatric morbidity, mortality and healthcare costs. Current molecular testing for rare genetic disorders is often a lengthy and costly endeavor, and in many cases a molecular diagnosis is never achieved despite extensive testing. Diseases with locus heterogeneity or overlapping signs and symptoms are especially challenging owing to the number of potential targets. Consequently, there is immense need for scalable, economical, rapid, multiplexed diagnostic testing for rare Mendelian diseases. Recent advances in next-generation sequencing and bioinformatic technologies have the potential to change the standard of care for the diagnosis of rare genetic disorders. These advances will be reviewed in the setting of a recently developed test for 592 autosomal recessive and X-linked diseases.
Assuntos
Doenças Genéticas Inatas/diagnóstico , Testes Genéticos/métodos , Técnicas de Diagnóstico Molecular/métodos , Doenças Raras/diagnóstico , Doenças Raras/genética , Criança , Pré-Escolar , Bases de Dados Genéticas , Testes Genéticos/economia , Variação Genética , Genótipo , Humanos , Técnicas de Diagnóstico Molecular/economia , Análise de Sequência de DNARESUMO
Of 7028 disorders with suspected Mendelian inheritance, 1139 are recessive and have an established molecular basis. Although individually uncommon, Mendelian diseases collectively account for ~20% of infant mortality and ~10% of pediatric hospitalizations. Preconception screening, together with genetic counseling of carriers, has resulted in remarkable declines in the incidence of several severe recessive diseases including Tay-Sachs disease and cystic fibrosis. However, extension of preconception screening to most severe disease genes has hitherto been impractical. Here, we report a preconception carrier screen for 448 severe recessive childhood diseases. Rather than costly, complete sequencing of the human genome, 7717 regions from 437 target genes were enriched by hybrid capture or microdroplet polymerase chain reaction, sequenced by next-generation sequencing (NGS) to a depth of up to 2.7 gigabases, and assessed with stringent bioinformatic filters. At a resultant 160x average target coverage, 93% of nucleotides had at least 20x coverage, and mutation detection/genotyping had ~95% sensitivity and ~100% specificity for substitution, insertion/deletion, splicing, and gross deletion mutations and single-nucleotide polymorphisms. In 104 unrelated DNA samples, the average genomic carrier burden for severe pediatric recessive mutations was 2.8 and ranged from 0 to 7. The distribution of mutations among sequenced samples appeared random. Twenty-seven percent of mutations cited in the literature were found to be common polymorphisms or misannotated, underscoring the need for better mutation databases as part of a comprehensive carrier testing strategy. Given the magnitude of carrier burden and the lower cost of testing compared to treating these conditions, carrier screening by NGS made available to the general population may be an economical way to reduce the incidence of and ameliorate suffering associated with severe recessive childhood disorders.