Dataset Information

Limitations of exome sequencing in detecting rare and undiagnosed diseases.

ABSTRACT: While exome sequencing (ES) is commonly the final diagnostic step in clinical genetics, it may miss diagnoses. To clarify the limitations of ES, we investigated the diagnostic yield of genetic tests beyond ES in our Undiagnosed Diseases Network (UDN) participants. We reviewed the yield of additional genetic testing including genome sequencing (GS), copy number variant (CNV), noncoding variant (NCV), repeat expansion (RE), or methylation testing in UDN cases with nondiagnostic ES results. Overall, 36/54 (67%) of total diagnoses were based on clinical findings and coding variants found by ES and 3/54 (6%) were based on clinical findings only. The remaining 15/54 (28%) required testing beyond ES. Of these, 7/15 (47%) had NCV, 6/15 (40%) CNV, and 2/15 (13%) had a RE or a DNA methylation disorder. Thus 18/54 (33%) of diagnoses were not solved exclusively by ES. Several methods were needed to detect and/or confirm the functional effects of the variants missed by ES, and in some cases by GS. These results indicate that tests to detect elusive variants should be considered after nondiagnostic preliminary steps. Further studies are needed to determine the cost-effectiveness of tests beyond ES that provide diagnoses and insights to possible treatment.

SUBMITTER: Burdick KJ

PROVIDER: S-EPMC8057342 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Limitations of exome sequencing in detecting rare and undiagnosed diseases.

Burdick Kendall J KJ Cogan Joy D JD Rives Lynette C LC Robertson Amy K AK Koziura Mary E ME Brokamp Elly E Duncan Laura L Hannig Vickie V Pfotenhauer Jean J Vanzo Rena R Paul Michael S MS Bican Anna A Morgan Thomas T Duis Jessica J Newman John H JH Hamid Rizwan R Phillips John A JA

American journal of medical genetics. Part A 20200319 6

While exome sequencing (ES) is commonly the final diagnostic step in clinical genetics, it may miss diagnoses. To clarify the limitations of ES, we investigated the diagnostic yield of genetic tests beyond ES in our Undiagnosed Diseases Network (UDN) participants. We reviewed the yield of additional genetic testing including genome sequencing (GS), copy number variant (CNV), noncoding variant (NCV), repeat expansion (RE), or methylation testing in UDN cases with nondiagnostic ES results. Overall ...[more]

PMID: 32190976

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Project description:One of the IRDiRC goals for 2017?2027 is to achieve definitive diagnosis for rare undiagnosed diseases within one year, as delay in diagnosis remains one of the pending issues in the rare diseases field. The Spanish Undiagnosed Rare Diseases Program (SpainUDP) was created in response to this challenging scenario to cover patients' needs and after seeing the success of the Undiagnosed Diseases Program (UDP) in the USA. SpainUDP offers a multidisciplinary approach to those patients who have long sought a diagnosis without any success. During the first phase of the protocol, undiagnosed cases are sent to SpainUDP by individual patients or families, patient organizations or hospitals. After careful analysis of phenotype, data from sequencing experiments (WES) is processed with a standard pipeline and detailed standardized phenotypic information (mapped to the Human Phenotype Ontology, HPO) is connected to genetic data. In addition, the participation of SpainUDP in international initiatives such as the European projects RD-Connect and Solve RD, the Undiagnosed Diseases Network International (UDNI), and the MatchMaker Exchange (MME) platform, allows the establishment of a global data sharing strategy across multiple projects submitting data to these international initiatives. From the official beginning of the program (at the end of 2015) until early 2018, 147 cases were accepted in SpainUDP. During this time, 37 cases (25%) dropped out the program due to several reasons. The remaining 110 cases are distributed as follows: phenotypic and genotypic (WES) characterization was finished in 30 cases, of which 20 (67%) were diagnosed; 21 cases are pending on variants' validation by Sanger sequencing; in 25 cases, WES is ongoing and 34 cases are being studied for deep phenotypic characterization. In conclusion, SpainUDP aims to achieve a diagnosis following two recommendations of the IRDiRC: the patients' diagnosis in as short a time as possible and the promotion of data sharing (especially genomic) at the international level.

Dataset Information

Limitations of exome sequencing in detecting rare and undiagnosed diseases.

Publications

Limitations of exome sequencing in detecting rare and undiagnosed diseases.

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