Mobile element insertion detection in 89,874 clinical exomes.

PURPOSE: Exome sequencing (ES) is increasingly used for the diagnosis of rare genetic disease. However, some pathogenic sequence variants within the exome go undetected due to the technical difficulty of identifying them. Mobile element insertions (MEIs) are a known cause of genetic disease in humans but have been historically difficult to detect via ES and similar targeted sequencing methods. METHODS: We developed and applied a novel MEI detection method prospectively to samples received for clinical ES beginning in November 2017. Positive MEI findings were confirmed by an orthogonal method and reported back to the ordering provider. In this study, we examined 89,874 samples from 38,871 cases. RESULTS: Diagnostic MEIs were present in 0.03% (95% binomial test confidence interval: 0.02-0.06%) of all cases and account for 0.15% (95% binomial test confidence interval: 0.08-0.25%) of cases with a molecular diagnosis. One diagnostic MEI was a novel founder event. Most patients with pathogenic MEIs had prior genetic testing, three of whom had previous negative DNA sequencing analysis of the diagnostic gene. CONCLUSION: MEI detection from ES is a valuable diagnostic tool, reveals molecular findings that may be undetected by other sequencing assays, and increases diagnostic yield by 0.15%.

Misattributed parentage as an unanticipated finding during exome/genome sequencing: current clinical laboratory practices and an opportunity for standardization.

PURPOSE: Clinical laboratories performing exome or genome sequencing (ES/GS) are familiar with the challenges associated with proper consenting for and reporting of medically actionable secondary findings based on recommendations from the American College of Medical Genetics and Genomics (ACMG). Misattributed parentage is another type of unanticipated finding a laboratory may encounter during family-based ES/GS; however, there are currently no professional recommendations related to the proper consenting for and reporting of misattributed parentage encountered during ES/GS. METHODS: We surveyed 10 clinical laboratories offering family-based ES/GS regarding their consent language, discovery, and reporting of misattributed parentage. RESULTS: Many laboratories have already developed their own practices/policies for these issues, which do not necessarily agree with those from other labs. CONCLUSION: There are several other possibilities besides true misattributed parentage that could result in similar laboratory findings, and laboratories often feel they lack sufficient information to make formal conclusions on a report regarding the true genetic relatedness of the submitted samples. However, understanding the genetic relatedness (or lack thereof) of the samples submitted for family-based ES/GS has medical relevance. Therefore, professional recommendations for the appropriate handling of suspected misattributed parentage encountered during ES/GS are needed to help standardize current clinical laboratory practices.

Genetic counseling in industry settings: Opportunities in the era of precision health.

The skill sets of genetic counselors are strongly utilized in industry, as evidenced by 20% of genetic counselors reporting employment within industry in 2016. In addition, industry genetic counselors are expanding their roles, taking on new responsibilities, and creating new opportunities. These advances have impacted the profession as a whole including, but not limited to, genetic counseling training curricula, a shift back to genetic counseling directly to patients, and a growing influence of genetic counselors on industry test offerings. Industry genetic counselors and training programs are working together to address the challenges and opportunities presented by workforce changes and novel interpretations of how genetic counselors' core competencies can be utilized. Counseling of patients by industry genetic counselors has become more commonplace and addresses a need for alternate service delivery models. Industry genetic counselors often provide significant contributions to test development, education, marketing, and interpretation. Beyond these broad examples, individual industry genetic counselors have created unique niches for themselves, using their genetic counseling training combined with unique opportunities offered through industry, as illustrated by genetic counselors' various roles and responsibilities highlighted here.

Whole-exome sequencing on deceased fetuses with ultrasound anomalies: expanding our knowledge of genetic disease during fetal development.

PurposeThe aim of this study was to determine the diagnostic yield of whole-exome sequencing (WES) in fetuses with ultrasound anomalies that resulted in fetal demise or pregnancy termination. The results were also utilized to aid in the identification of candidate genes for fetal development and to expand the clinical phenotype of known genetic conditions.MethodsWES was performed on specimens from 84 deceased fetuses. Data were analyzed and final results were classified into one of four categories: positive, possible, negative, and candidate gene only. WES analysis was predominantly performed in fetus-parent trios or quads (61%, n=52).ResultsOverall, 20% (n = 17) of cases were positive, 45% (n=38) were possible, 9% (n=7) had only candidate gene variants and 26% (n = 22) tested negative. The diagnostic yield for definitive findings for trio analysis was 24% (n = 11) compared to 14% (n = 4) for singletons. The most frequently reported ultrasound anomalies were central nervous system (37%, n = 31), hydrops/edema (36%, n = 30), and cardiovascular anomalies (31%, n = 26).ConclusionOur experience supports the use of WES to identify the molecular etiology of fetal ultrasound anomalies, to identify candidate genes involved in fetal development, and to expand our knowledge of the clinical phenotype of known genetic conditions.

Clinical application of whole-exome sequencing across clinical indications.

PURPOSE: We report the diagnostic yield of whole-exome sequencing (WES) in 3,040 consecutive cases at a single clinical laboratory. METHODS: WES was performed for many different clinical indications and included the proband plus two or more family members in 76% of cases. RESULTS: The overall diagnostic yield of WES was 28.8%. The diagnostic yield was 23.6% in proband-only cases and 31.0% when three family members were analyzed. The highest yield was for patients who had disorders involving hearing (55%, N = 11), vision (47%, N = 60), the skeletal muscle system (40%, N = 43), the skeletal system (39%, N = 54), multiple congenital anomalies (36%, N = 729), skin (32%, N = 31), the central nervous system (31%, N = 1,082), and the cardiovascular system (28%, N = 54). Of 2,091 cases in which secondary findings were analyzed for 56 American College of Medical Genetics and Genomics-recommended genes, 6.2% (N = 129) had reportable pathogenic variants. In addition to cases with a definitive diagnosis, in 24.2% of cases a candidate gene was reported that may later be reclassified as being associated with a definitive diagnosis. CONCLUSION: Our experience with our first 3,040 WES cases suggests that analysis of trios significantly improves the diagnostic yield compared with proband-only testing for genetically heterogeneous disorders and facilitates identification of novel candidate genes.Genet Med 18 7, 696-704.

Whole exome sequencing reveals de novo pathogenic variants in KAT6A as a cause of a neurodevelopmental disorder.

Neurodevelopmental disorders (NDD) are common, with 1-3% of general population being affected, but the etiology is unknown in most individuals. Clinical whole-exome sequencing (WES) has proven to be a powerful tool for the identification of pathogenic variants leading to Mendelian disorders, among which NDD represent a significant percentage. Performing WES with a trio-approach has proven to be extremely effective in identifying de novo pathogenic variants as a common cause of NDD. Here we report six unrelated individuals with a common phenotype consisting of NDD with severe speech delay, hypotonia, and facial dysmorphism. These patients underwent WES with a trio approach and de novo heterozygous predicted pathogenic novel variants in the KAT6A gene were identified. The KAT6A gene encodes a histone acetyltransfrease protein and it has long been known for its structural involvement in acute myeloid leukemia; however, it has not previously been associated with any congenital disorder. In animal models the KAT6A ortholog is involved in transcriptional regulation during development. Given the similar findings in animal models and our patient's phenotypes, we hypothesize that KAT6A could play a role in development of the brain, face, and heart in humans. © 2016 Wiley Periodicals, Inc.

WAC loss-of-function mutations cause a recognisable syndrome characterised by dysmorphic features, developmental delay and hypotonia and recapitulate 10p11.23 microdeletion syndrome.

BACKGROUND: Rare de novo mutations have been implicated as a significant cause of idiopathic intellectual disability. Large deletions encompassing 10p11.23 have been implicated in developmental delay, behavioural abnormalities and dysmorphic features, but the genotype-phenotype correlation was not delineated. Mutations in WAC have been recently reported in large screening cohorts of patients with intellectual disability or autism, but no full phenotypic characterisation was described. METHODS: Clinical and molecular characterisation of six patients with loss-of-function WAC mutations identified by whole exome sequencing was performed. Clinical data were obtained by retrospective chart review, parental interviews, direct patient interaction and formal neuropsychological evaluation. RESULTS: Five heterozygous de novo WAC mutations were identified in six patients. Three of the mutations were nonsense, and two were frameshift; all are predicted to cause loss of function either through nonsense-mediated mRNA decay or protein truncation. Clinical findings included developmental delay (6/6), hypotonia (6/6), behavioural problems (5/6), eye abnormalities (5/6), constipation (5/6), feeding difficulties (4/6), seizures (2/6) and sleep problems (2/6). All patients exhibited common dysmorphic features, including broad/prominent forehead, synophrys and/or bushy eyebrows, depressed nasal bridge and bulbous nasal tip. Posteriorly rotated ears, hirsutism, deep-set eyes, thin upper lip, inverted nipples, hearing loss and branchial cleft anomalies were also noted. CONCLUSIONS: Our case series show that loss-of-function mutations in WAC cause a recognisable genetic syndrome characterised by a neurocognitive phenotype and facial dysmorphism. Our data highly suggest that WAC haploinsufficiency is responsible for most of the phenotypic features associated with deletions encompassing 10p11.23.

A SOX5 gene variant as a possible contributor to short stature.

SUMMARY: SOX5 plays an important role in chondrogenesis and chondrocyte differentiation. SOX5 defects in humans (often deletions) result in a Lamb-Shaffer syndrome (LSS), presenting with speech delay, behavioral problems and minor dysmorphic features. We present a patient with idiopathic short stature (ISS) who carried a heterozygous novel variant in SOX5. The patient had no dysmorphic features, but a skeletal survey revealed minor skeletal abnormalities. Laboratory and endocrine evaluation for known causes of growth disorders was negative. The missense variant in SOX5 gene (c.1783A>G, p.K595E) was de novo and was predicted to be deleterious by in silico programs. In summary, we present a patient whose presentation may provide evidence that gene defects in SOX5 may contribute to the etiology of short stature and/or mild skeletal defects beyond LSS. LEARNING POINTS: We report a girl with idiopathic short stature and mild skeletal defects presenting with a de novo variant in SOX5 gene, predicted in silico to be deleterious. Although SOX5 has not been previously specifically associated with short stature, several evidences support its contributing effect on dyschondrogenesis. Missense variants in SOX5 gene may lead to mild phenotypes, differing from typical presentation of patients with Lamb-Shaffer syndrome.

Considering the Benefits and Risks of Research Participants' Access to Sequence Data.

The use of sequencing technologies has greatly expanded in both research and clinical settings. The generation of voluminous datasets has raised several issues regarding data sharing and access. Current regulations require clinical laboratories and some research laboratories to provide access to test data, including sequencing data, directly to patients upon request. There is some controversy over whether this access right may be somewhat broader, encompassing research data as well-a question beyond the scope of this article. It is clear that in the research setting, deposition of sequencing data into public or private databases often occurs, although little information exists about the return of data files to research participants (in contrast to the extensive deliberations regarding return of results). Thus, further consideration of the issue of access to data files is warranted as well as more effort to understand both patients' and research participants' use of the data.

Affinity enhancement of an in vivo matured therapeutic antibody using structure-based computational design.

Improving the affinity of a high-affinity protein-protein interaction is a challenging problem that has practical applications in the development of therapeutic biomolecules. We used a combination of structure-based computational methods to optimize the binding affinity of an antibody fragment to the I-domain of the integrin VLA1. Despite the already high affinity of the antibody (Kd approximately 7 nM) and the moderate resolution (2.8 A) of the starting crystal structure, the affinity was increased by an order of magnitude primarily through a decrease in the dissociation rate. We determined the crystal structure of a high-affinity quadruple mutant complex at 2.2 A. The structure shows that the design makes the predicted contacts. Structural evidence and mutagenesis experiments that probe a hydrogen bond network illustrate the importance of satisfying hydrogen bonding requirements while seeking higher-affinity mutations. The large and diverse set of interface mutations allowed refinement of the mutant binding affinity prediction protocol and improvement of the single-mutant success rate. Our results indicate that structure-based computational design can be successfully applied to further improve the binding of high-affinity antibodies.

De novo pathogenic variants in CHAMP1 are associated with global developmental delay, intellectual disability, and dysmorphic facial features.

We identified five unrelated individuals with significant global developmental delay and intellectual disability (ID), dysmorphic facial features and frequent microcephaly, and de novo predicted loss-of-function variants in chromosome alignment maintaining phosphoprotein 1 (CHAMP1). Our findings are consistent with recently reported de novo mutations in CHAMP1 in five other individuals with similar features. CHAMP1 is a zinc finger protein involved in kinetochore-microtubule attachment and is required for regulating the proper alignment of chromosomes during metaphase in mitosis. Mutations in CHAMP1 may affect cell division and hence brain development and function, resulting in developmental delay and ID.

Novel large deletion in the ACTA1 gene in a child with autosomal recessive nemaline myopathy.

Nemaline myopathy (NM) is a genetically and clinically heterogeneous disorder resulting from a disruption of the thin filament proteins of the striated muscle sarcomere. The disorder is typically characterized by muscle weakness including the face, neck, respiratory, and limb muscles and is clinically classified based on the age of onset and severity. Mutations in the ACTA1 gene contribute to a significant proportion of NM cases. The majority of ACTA1 gene mutations are missense mutations causing autosomal dominant NM by producing an abnormal protein. However, approximately 10% of ACTA1 gene mutations are associated with autosomal recessive NM; these mutations are associated with loss of protein function. We report the first case of a large deletion in the ACTA1 gene contributing to autosomal recessive NM. This case illustrates the importance of understanding disease mechanisms at the molecular level to accurately infer the inheritance pattern and potentially aid with clinical management.

Identification of a c.601C>G mutation in the CCM1 gene in a kindred with multiple skin, spinal and cerebral cavernous malformations.

Cerebral cavernous malformations (CCM) are congenital vascular anomalies predominantly of the central nervous system but may include lesions in other tissues such as the retina, skin, and liver. These hamartomatous dysplasias, generally occurring sporadically, consist of dynamic clustered convoluted capillary cavities without intervening brain parenchyma that may lead to headaches, seizures, paresis, cerebral hemorrhages and focal neurological deficits. Familial forms of CCM, inherited in an autosomal dominant manner with incomplete penetrance and variable expression, are attributed to mutations in three genes, CCM1, CCM2 and CCM3. Here, we report a kindred of Persian descent exhibiting a range of clinical symptoms and features that include seizures, multiple lesions of the brain and spinal cord, and severe hyperkeratotic cutaneous capillary-venous malformations. Sanger DNA sequencing and deletion/duplication testing of the CCM1, CCM2, and CCM3 genes in the proband revealed a CCM1 c.601C>G mutation. Targeted mutation analysis in family members confirmed that this mutation segregated with the disease in the family. This family illustrates the phenotypic heterogeneity that has been observed in other reported CCM-pedigrees and highlights the importance of genetic testing for early diagnosis in familial CCM. To our knowledge, this is the first genetic investigation of CCM in the Persian population.