Gain and loss of TASK3 channel function and its regulation by novel variation cause KCNK9 imprinting syndrome.

BACKGROUND: Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for KCNK9 imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood. METHODS: This study discovers mechanisms underlying KCNK9 imprinting syndrome (KIS) by describing 15 novel KCNK9 alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies. RESULTS: We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of KCNK9 variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of KCNK9 genetic variants, however, was altered channel regulation. CONCLUSIONS: This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of KCNK9 variation on channel function and regulation.

Genomics Integration Into Nephrology Practice.

RATIONALE & OBJECTIVE: The etiology of kidney disease remains unknown in many individuals with chronic kidney disease (CKD). We created the Mayo Clinic Nephrology Genomics Clinic to improve our ability to integrate genomic and clinical data to identify the etiology of unexplained CKD. STUDY DESIGN: Retrospective study. SETTING & PARTICIPANTS: An essential component of our program is the Nephrology Genomics Board which consists of nephrologists, geneticists, pathologists, translational omics scientists, and trainees who interpret the patient's clinical and genetic data. Since September 2016, the Board has reviewed 163 cases (15 cystic, 100 glomerular, 6 congenital anomalies of kidney and urinary tract (CAKUT), 20 stones, 15 tubulointerstitial, and 13 other). ANALYTICAL APPROACH: Testing was performed with targeted panels, single gene analysis, or analysis of kidney-related genes from exome sequencing. Variant classification was obtained based on the 2015 American College of Medical Genetics and Genomics and the Association for Molecular Pathology guidelines. RESULTS: A definitive genetic diagnosis was achieved for 50 families (30.7%). The highest diagnostic yield was obtained in individuals with tubulointerstitial diseases (53.3%), followed by congenital anomalies of the kidney and urological tract (33.3%), glomerular (31%), cysts (26.7%), stones (25%), and others (15.4%). A further 20 (12.3%) patients had variants of interest, and variant segregation, and research activities (exome, genome, or transcriptome sequencing) are ongoing for 44 (40%) unresolved families. LIMITATIONS: Possible overestimation of diagnostic rate due to inclusion of individuals with variants with evidence of pathogenicity but classified as of uncertain significance by the clinical laboratory. CONCLUSIONS: Integration of genomic and research testing and multidisciplinary evaluation in a nephrology cohort with CKD of unknown etiology or suspected monogenic disease provided a diagnosis in a third of families. These diagnoses had prognostic implications, and often changes in management were implemented.

Rare TBX4 Variant Causing Pulmonary Arterial Hypertension With Small Patella Syndrome in an Adult Man.

Small patella syndrome presents with small or absent patellae and may result in pulmonary arterial hypertension, typically in children. A pathogenic canonical splice site variant, c.1021+1G>A in the T-box transcription factor 4 (TBX4) gene, currently not included in commercial gene panel, was detected in an adult with pulmonary arterial hypertension and absent patellae. (Level of Difficulty: Advanced.).

Clinically Actionable Findings Derived From Predictive Genomic Testing Offered in a Medical Practice Setting.

OBJECTIVE: To assess the presence of clinically actionable results and other genetic findings in an otherwise healthy population of adults seen in a medical practice setting and offered "predictive" genomic testing. PATIENTS AND METHODS: In 2014, a predictive genomics clinic for generally healthy adults was launched through the Mayo Clinic Executive Health Program. Self-identified interested patients met with a genomic nurse and genetic counselor for pretest advice and education. Two genome sequencing platforms and one gene panel-based health screen were offered. Posttest genetic counseling was available for patients who elected testing. From March 1, 2014, through June 1, 2019, 1281 patients were seen and 301 (23.5%) chose testing. Uptake rates increased to 36.3% [70 of 193]) in 2019 from 11.8% [2 of 17] in 2014. Clinically actionable results and genetic findings were analyzed using descriptive statistics. RESULTS: Clinically actionable results were detected in 11.6% of patients (35 of 301), and of those, 51.7% (15 of 29) with a cancer or cardiovascular result = did not have a personal or family history concerning for a hereditary disorder. The most common actionable results were in the BCHE, BRCA2, CHEK2, LDLR, MUTYH, and MYH7 genes. A carrier of at least one recessive condition was found in 53.8% of patients (162 of 301). At least one variant associated with multifactorial disease was found in 44.5% (134 of 301) (eg, 25 patients were heterozygous for the F5 factor V Leiden variant associated with thrombophilia risk). CONCLUSION: Our predictive screening revealed that 11.6% of individuals will test positive for a clinically actionable, likely pathogenic/pathogenic variant. This finding suggests that wider knowledge and adoption of predictive genomic services could be beneficial in medical practice, although additional studies are needed.

Impact of integrated translational research on clinical exome sequencing.

PURPOSE: Exome sequencing often identifies pathogenic genetic variants in patients with undiagnosed diseases. Nevertheless, frequent findings of variants of uncertain significance necessitate additional efforts to establish causality before reaching a conclusive diagnosis. To provide comprehensive genomic testing to patients with undiagnosed disease, we established an Individualized Medicine Clinic, which offered clinical exome testing and included a Translational Omics Program (TOP) that provided variant curation, research activities, or research exome sequencing. METHODS: From 2012 to 2018, 1101 unselected patients with undiagnosed diseases received exome testing. Outcomes were reviewed to assess impact of the TOP and patient characteristics on diagnostic rates through descriptive and multivariate analyses. RESULTS: The overall diagnostic yield was 24.9% (274 of 1101 patients), with 174 (15.8% of 1101) diagnosed on the basis of clinical exome sequencing alone. Four hundred twenty-three patients with nondiagnostic or without access to clinical exome sequencing were evaluated by the TOP, with 100 (9% of 1101) patients receiving a diagnosis, accounting for 36.5% of the diagnostic yield. The identification of a genetic diagnosis was influenced by the age at time of testing and the disease phenotype of the patient. CONCLUSION: Integration of translational research activities into clinical practice of a tertiary medical center can significantly increase the diagnostic yield of patients with undiagnosed disease.

De novo TBR1 variants cause a neurocognitive phenotype with ID and autistic traits: report of 25 new individuals and review of the literature.

TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands.

Variable expressivity of syndromic BMP4-related eye, brain, and digital anomalies: A review of the literature and description of three new cases.

Microphthalmia with brain and digital anomalies (MCOPS6, MIM# 607932) is an autosomal dominant disorder caused by loss-of-function variants or large deletions involving BMP4, which encodes bone morphogenetic protein 4, a member of the TGF-ß protein superfamily. BMP4 has a number of roles in embryonic development including neurogenesis, lens induction, development of cartilage and bone, urogenital development, limb and digit patterning, hair follicle regeneration, as well as tooth formation. In addition to syndromic microphthalmia, BMP4 variants have been implicated in non-syndromic cleft lip with or without cleft palate and congenital healed cleft lip indicating different allelic presentations. MCOPS6 subjects may also lack some of the major phenotypic hallmarks of the disorder, including microphthalmia, indicating variable expressivity. As only a handful of individuals with MCOPS6 have been described, we review the clinical findings in previously reported cases with either deletions or loss-of-function variants in BMP4. We describe three new cases, including two subjects with novel deletions and one subject with a likely pathogenic de novo nonsense variant [c.1052C>G, p.(S351*)] in BMP4. One of the subjects had dual molecular diagnoses including a co-occurring microdeletion at 17q21.31 associated with Koolen de Vries syndrome, which has a partially overlapping disease phenotype. None of these individuals had clinically apparent microphthalmia or anopthalmia, which have been reported in a majority of previously described cases. One subject had exophthalmia and strabismus, while another had bilateral Peters anomaly and sclerocornea, thus expanding the phenotype associated with BMP4 loss-of-function variants.

Exome sequencing confirms diagnosis of kabuki syndrome in an-adult with hodgkin lymphoma and unusually severe multisystem phenotype.

We report a 34-year-old male patient with a novel variant in KMT2D gene, which finally ended a quest for a diagnosis that was clinically suspected in the past, prior the molecular basis of Kabuki Syndrome (KS) was known. The patient showcases the multisystemic features, with involvement of all previously associated with KS body systems, presence of immune deficiency as well as autoimmune disorders, requiring three pancreatic transplants. We also report, for the first time to our knowledge, the presence of epidural lipomatosis and Hodgkin Lymphoma in a patient with KS.

De Novo Pathogenic Variants in CACNA1E Cause Developmental and Epileptic Encephalopathy with Contractures, Macrocephaly, and Dyskinesias.

Developmental and epileptic encephalopathies (DEEs) are severe neurodevelopmental disorders often beginning in infancy or early childhood that are characterized by intractable seizures, abundant epileptiform activity on EEG, and developmental impairment or regression. CACNA1E is highly expressed in the central nervous system and encodes the α1-subunit of the voltage-gated CaV2.3 channel, which conducts high voltage-activated R-type calcium currents that initiate synaptic transmission. Using next-generation sequencing techniques, we identified de novo CACNA1E variants in 30 individuals with DEE, characterized by refractory infantile-onset seizures, severe hypotonia, and profound developmental impairment, often with congenital contractures, macrocephaly, hyperkinetic movement disorders, and early death. Most of the 14, partially recurring, variants cluster within the cytoplasmic ends of all four S6 segments, which form the presumed CaV2.3 channel activation gate. Functional analysis of several S6 variants revealed consistent gain-of-function effects comprising facilitated voltage-dependent activation and slowed inactivation. Another variant located in the domain II S4-S5 linker results in facilitated activation and increased current density. Five participants achieved seizure freedom on the anti-epileptic drug topiramate, which blocks R-type calcium channels. We establish pathogenic variants in CACNA1E as a cause of DEEs and suggest facilitated R-type calcium currents as a disease mechanism for human epilepsy and developmental disorders.

Pharmacogenomic findings from clinical whole exome sequencing of diagnostic odyssey patients.

BACKGROUND: We characterized the pharmacogenomics (PGx) results received by diagnostic odyssey patients as secondary findings during clinical whole exome sequencing (WES) testing as a part of their care in Mayo Clinic's Individualized Medicine Clinic to determine the potential benefits and limitations to this cohort. METHODS: WES results on 94 patients included a subset of PGx variants in CYP2C19,CYP2C9, and VKORC1 if identified in the patient. Demographic, phenotypic, and medication usage information was abstracted from patient medical data. A pharmacist interpreted the PGx results in the context of the patients' current medication use and made therapeutic recommendations. RESULTS: The majority was young with a median age of 10 years old, had neurological involvement in the disease presentation (71%), and was currently taking medications (90%). Of the 94 PGx-evaluated patients, 91% had at least one variant allele reported and 20% had potential immediate implications on current medication use. CONCLUSION: Due to the disease complexity and medication needs of diagnostic odyssey patients, there may be immediate benefit obtained from early life PGx testing for many and most will likely find benefit in the future. These results require conscientious interpretation and management to be actionable for all prescribing physicians throughout the lifetime of the patient.

Shared decision-making following disclosure of coronary heart disease genetic risk: results from a randomized clinical trial.

Whether disclosure of genetic risk for coronary heart disease (CHD) influences shared decision-making (SDM) regarding use of statins to reduce CHD risk is unknown. We randomized 207 patients, age 45-65 years, at intermediate CHD risk, and not on statins, to receive the 10-year risk of CHD based on conventional risk factors alone (n=103) or in combination with a genetic risk score (n=104). A genetic counselor disclosed this information followed by a physician visit for SDM regarding statin therapy. A novel decision aid was used in both encounters to disclose the CHD risk estimates and facilitate SDM regarding statin use. Patients reported their decision quality and physician visit satisfaction using validated surveys. There were no statistically significant differences between the two groups in the SDM score, satisfaction with the clinical encounter, perception of the quality of the discussion or of participation in decision-making and physician visit satisfaction scores. Quantitative analyses of a random subset of 80 video-recorded encounters using the OPTION5 scale also showed no significant difference in SDM between the two groups. Disclosure of CHD genetic risk using an electronic health record-linked decision aid did not adversely affect SDM or patients' satisfaction with the clinical encounter. TRIAL REGISTRATION NUMBER: NCT01936675; Results.

Determining the frequency of pathogenic germline variants from exome sequencing in patients with castrate-resistant prostate cancer.

OBJECTIVES: To determine the frequency of pathogenic inherited mutations in 157 select genes from patients with metastatic castrate-resistant prostate cancer (mCRPC). DESIGN: Observational. SETTING: Multisite US-based cohort. PARTICIPANTS: Seventy-one adult male patients with histological confirmation of prostate cancer, and had progressive disease while on androgen deprivation therapy. RESULTS: Twelve patients (17.4%) showed evidence of carrying pathogenic or likely pathogenic germline variants in the ATM, ATR, BRCA2, FANCL, MSR1, MUTYH, RB1, TSHR and WRN genes. All but one patient opted in to receive clinically actionable results at the time of study initiation. We also found that pathogenic germline BRCA2 variants appear to be enriched in mCRPC compared to familial prostate cancers. CONCLUSIONS: Pathogenic variants in cancer-susceptibility genes are frequently observed in patients with mCRPC. A substantial proportion of patients with mCRPC or their family members would derive clinical utility from mutation screening. TRIAL REGISTRATION NUMBER: NCT01953640; Results.

Evaluation of the Mayo Clinic Phenotype-Based Genotype Predictor Score in Patients with Clinically Diagnosed Hypertrophic Cardiomyopathy.

Genetic testing for hypertrophic cardiomyopathy (HCM) can provide an important clinical marker for disease outcome and family screening. This study set out to validate our recently developed phenotype-based HCM genotype predictor score. Patients clinically diagnosed with HCM and evaluated by genetic counselors comprised the study cohort. Genotype score was derived based on clinical and echocardiographic variables. Total score was correlated with the yield of genetic testing. Of 564 HCM patients, 198 sought genetic testing (35 %; 55 % male; mean age at diagnosis, 50 ± 20 years). Of these, 101 patients (51 %) were genotype positive for a HCM-associated genetic mutation (55 % male; mean age at diagnosis, 42 ± 18 years). Cochran-Armitage analysis showed similar, statistically significant trends of increased yields for higher genotype scores for both the original and study cohort. Validated by the current study, this scoring system provides an easy-to-use, clinical tool to aid in determining the likelihood of a positive HCM genetic test.

Incorporating a Genetic Risk Score Into Coronary Heart Disease Risk Estimates: Effect on Low-Density Lipoprotein Cholesterol Levels (the MI-GENES Clinical Trial).

BACKGROUND: Whether knowledge of genetic risk for coronary heart disease (CHD) affects health-related outcomes is unknown. We investigated whether incorporating a genetic risk score (GRS) in CHD risk estimates lowers low-density lipoprotein cholesterol (LDL-C) levels. METHODS AND RESULTS: Participants (n=203, 45-65 years of age, at intermediate risk for CHD, and not on statins) were randomly assigned to receive their 10-year probability of CHD based either on a conventional risk score (CRS) or CRS + GRS ((+)GRS). Participants in the (+)GRS group were stratified as having high or average/low GRS. Risk was disclosed by a genetic counselor followed by shared decision making regarding statin therapy with a physician. We compared the primary end point of LDL-C levels at 6 months and assessed whether any differences were attributable to changes in dietary fat intake, physical activity levels, or statin use. Participants (mean age, 59.4±5 years; 48% men; mean 10-year CHD risk, 8.5±4.1%) were allocated to receive either CRS (n=100) or (+)GRS (n=103). At the end of the study period, the (+)GRS group had a lower LDL-C than the CRS group (96.5±32.7 versus 105.9±33.3 mg/dL; P=0.04). Participants with high GRS had lower LDL-C levels (92.3±32.9 mg/dL) than CRS participants (P=0.02) but not participants with low GRS (100.9±32.2 mg/dL; P=0.18). Statins were initiated more often in the (+)GRS group than in the CRS group (39% versus 22%, P<0.01). No significant differences in dietary fat intake and physical activity levels were noted. CONCLUSIONS: Disclosure of CHD risk estimates that incorporated genetic risk information led to lower LDL-C levels than disclosure of CHD risk based on conventional risk factors alone. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01936675.

Characterization of a phenotype-based genetic test prediction score for unrelated patients with hypertrophic cardiomyopathy.

OBJECTIVES: To determine the prevalence and spectrum of mutations and genotype-phenotype relationships in the largest hypertrophic cardiomyopathy (HCM) cohort to date and to provide an easy, clinically applicable phenotype-derived score that provides a pretest probability for a positive HCM genetic test result. PATIENTS AND METHODS: Between April 1, 1997, and February 1, 2007, 1053 unrelated patients with the clinical diagnosis of HCM (60% male; mean ± SD age at diagnosis, 44.4 ± 19 years) had HCM genetic testing for the 9 HCM-associated myofilament genes. Phenotyping was performed by review of electronic medical records. RESULTS: Overall, 359 patients (34%) were genotype positive for a putative HCM-associated mutation in 1 or more HCM-associated genes. Univariate and multivariate analyses identified the echocardiographic reverse curve morphological subtype, an age at diagnosis younger than 45 years, a maximum left ventricular wall thickness of 20 mm or greater, a family history of HCM, and a family history of sudden cardiac death as positive predictors of positive genetic test results, whereas hypertension was a negative predictor. A score, based on the number of predictors of a positive genetic test result, predicted a positive genetic test result ranging from 6% when only hypertension was present to 80% when all 5 positive predictor markers were present. CONCLUSION: In this largest HCM cohort published to date, the overall yield of genetic testing was 34%. Although all the patients were diagnosed clinically as having HCM, the presence or absence of 6 simple clinical/echocardiographic markers predicted the likelihood of mutation-positive HCM. Phenotype-guided genetic testing using the Mayo HCM Genotype Predictor score provides an easy tool for an effective genetic counseling session.