Postmortem Diagnostic Exome Sequencing Identifies a De Novo TUBB3 Alteration in a Newborn With Prenatally Diagnosed Hydrocephalus and Suspected Walker-Warburg Syndrome.

Objective Herein, we report a case of a deceased newborn with prenatally detected hydrocephalus. Postnatal findings included abnormal brain imaging and electroencephalogram, optic nerve abnormalities, and elevated creatine kinase (CK). No underlying genetic etiology had been previously identified for the proband, despite testing with a congenital muscular dystrophy gene panel. Methods Diagnostic exome sequencing (DES) was performed on the proband-parents trio, and candidate alterations were confirmed using automated fluorescence dideoxy sequencing. Results Exome sequencing of the proband, mother and father identified a previously unreported apparently de novo heterozygous tubulin, beta-3 ( TUBB3) c.523G>C (p.V175L) alteration in the proband. Conclusion Overall, DES established a likely molecular genetic diagnosis for a postmortem case after traditional testing methods were uninformative. The DES results allowed for reproductive options, such as preimplantation genetic diagnosis and/or prenatal diagnosis, to be available to the parents in future pregnancies.

Diagnostic exome sequencing for patients with a family history of consanguinity: over 38% of positive results are not autosomal recessive pattern.

Diagnostic exome sequencing (DES) is an effective tool for diagnosis in intractable cases where the underlying cause is thought be genetic. It is commonly assumed that patients with a family history of consanguinity will have increased detection rates for rare autosomal recessive Mendelian disorders through DES. Herein, we analyzed the diagnostic yield and relevant inheritance patterns within the DES cases with a reported consanguineous family history. Of the first 500 unselected cases referred for DES, 40 (8.0%) had a known consanguineous family history. Among the 40 cases, 13 (32.5%) received a definitive molecular diagnosis through DES and such positive rate is similar to that of families with no reported consanguinity (139/460, 30.2%, P=0.63). Although homozygous alterations likely related to consanguinity have been identified in eight positive cases, the other five (38.4%) causative mutations were unrelated to autosomal recessive inheritance. Our retrospective analysis demonstrated that individuals with known consanguinity were not more likely to have a positive DES result and a significant portion of the positive findings were not within an autosomal recessive gene. These results highlight that all applicable inheritance patterns should be considered for patients with a known family history of consanguinity.

Exome sequencing positively identified relevant alterations in more than half of cases with an indication of prenatal ultrasound anomalies.

OBJECTIVE: Exome sequencing is a successful option for diagnosing individuals with previously uncharacterized genetic conditions, however little has been reported regarding its utility in a prenatal setting. The goal of this study is to describe the results from a cohort of fetuses for which exome sequencing was performed. METHODS: We performed a retrospective analysis of the first seven cases referred to our laboratory for exome sequencing following fetal demise or termination of pregnancy. All seven pregnancies had multiple congenital anomalies identified by level II ultrasound. Exome sequencing was performed on trios using cultured amniocytes or products of conception from the affected fetuses. RESULTS: Relevant alterations were identified in more than half of the cases (4/7). Three of the four were categorized as 'positive' results, and one of the four was categorized as a 'likely positive' result. The provided diagnoses included osteogenesis imperfecta II (COL1A2), glycogen storage disease IV (GBE1), oral-facial-digital syndrome 1 (OFD1), and RAPSN-associated fetal akinesia deformation sequence. CONCLUSION: This data suggests that exome sequencing is likely to be a valuable diagnostic testing option for pregnancies with multiple congenital anomalies detected by prenatal ultrasound; however, additional studies with larger cohorts of affected pregnancies are necessary to confirm these findings.