Novel KDM6A Kabuki Syndrome Mutation With Hyperinsulinemic Hypoglycemia and Pulmonary Hypertension Requiring ECMO.

Kabuki syndrome (KS) is a multisystem disorder estimated to occur in 1:32 000 newborns. Pathogenic mutations cause the majority but not all cases of KS in either KMT2D or KDM6A. KS can be suspected by phenotypic features, including infantile hypotonia, developmental delay, dysmorphic features, congenital heart defects, and others. Still, many of these features are not readily apparent in a newborn. Although neonatal hypoglycemia has been reported in 8% to 10% of patients with KS, the incidence and severity of hyperinsulinemic hypoglycemia (HH) is not well-studied. We present a full-term female infant with HH who was responsive to low-dose diazoxide. At 3 months of age, she was admitted for septic shock, worsening respiratory status, and severe pulmonary hypertension, requiring extracorporeal membrane oxygenation support. Her neonatal history was notable for hypotonia, dysphagia with aspiration requiring gastrostomy tube placement, and a cardiac defect-hypoplastic aortic arch requiring aortic arch repair. She has characteristic facial features, including prominent eyelashes, long palpebral fissures, and a short nasal columella. Next-generation sequencing for HH revealed a de novo likely pathogenic missense variant in KDM6A gene: c.3479G > T, p.Gly1160Val that was absent from population databases. Genetic testing for causes of HH should include testing of the KS genes KMT2D and KDM6A. Early detection of the underlying genetic defect will help guide management as all reported HH cases associated with KS have been responsive to diazoxide. Affected infants with underlying cardiac conditions may be at higher risk of serious respiratory complications such as pulmonary hypertension.

The relationship between performance on the medical genetics and genomics in-training and certifying examinations.

PURPOSE: The American Board of Medical Genetics and Genomics (ABMGG) certifying examinations (CEs) are designed to assess relevant basic knowledge, clinical knowledge, and diagnostic skills of board-eligible candidates in primary specialty areas. The ABMGG in-training examinations (ITEs) provide formative feedback regarding knowledge and learning over time and assess readiness to attempt board certification. This study addresses the validity of the ABMGG ITE by evaluating its relationship with performance on CE utilizing established psychometric approaches. METHODS: Statistical analysis included bivariate Pearson correlation coefficients and linear regression to evaluate the strength of associations between ITE scores and CE scores. Logistic regression was used to assess the association between ITE scores and the probability of passing each CE. RESULTS: Logistic regression results indicated that ITE scores accounted for 22% to 44% of the variability in CE outcomes. Across 3 certification cycles, for every 1-point increase in ITE scores, the odds ratio for earning a passing score increased by a factor of 1.12 to 1.20 for the general CE, 1.14 to 1.25 for the clinical CE, and 1.12 to 1.20 for the laboratory CEs. CONCLUSION: The findings show a positive correlation between performance on the ITE examination and performance on and passing the ABMGG CE.

Variants in the SK2 channel gene (KCNN2) lead to dominant neurodevelopmental movement disorders.

KCNN2 encodes the small conductance calcium-activated potassium channel 2 (SK2). Rodent models with spontaneous Kcnn2 mutations show abnormal gait and locomotor activity, tremor and memory deficits, but human disorders related to KCNN2 variants are largely unknown. Using exome sequencing, we identified a de novo KCNN2 frameshift deletion in a patient with learning disabilities, cerebellar ataxia and white matter abnormalities on brain MRI. This discovery prompted us to collect data from nine additional patients with de novo KCNN2 variants (one nonsense, one splice site, six missense variants and one in-frame deletion) and one family with a missense variant inherited from the affected mother. We investigated the functional impact of six selected variants on SK2 channel function using the patch-clamp technique. All variants tested but one, which was reclassified to uncertain significance, led to a loss-of-function of SK2 channels. Patients with KCNN2 variants had motor and language developmental delay, intellectual disability often associated with early-onset movement disorders comprising cerebellar ataxia and/or extrapyramidal symptoms. Altogether, our findings provide evidence that heterozygous variants, likely causing a haploinsufficiency of the KCNN2 gene, lead to novel autosomal dominant neurodevelopmental movement disorders mirroring phenotypes previously described in rodents.

Training the next generation of genomic medicine providers: trends in medical education and national assessment.

PURPOSE: To assess the utilization of genetics on the United States Medical Licensing Examination (USMLE®). METHODS: A team of clinical genetics educators performed an analysis of the representation of genetics content on a robust sample of recent Step 1, Step 2 Clinical Knowledge (CK), and Step 3 examination forms. The content of each question was mapped to curriculum recommendations from the peer reviewed Association of Professors of Human and Medical Genetics white paper, Medical School Core Curriculum in Genetics, and the USMLE Content Outline. RESULTS: The committee identified 13.4%, 10.4%, and 4.4% of Steps 1, 2 and 3 respectively, as having genetics content. The genetics content of the exams became less pertinent to the questions from Step 1 to 3, with decreasing genetics content by exam and increasing percentages of questions identified as having genetics content in the distractors only. CONCLUSION: The current distribution of genetics in USMLE licensing examinations reflects traditional curricular approaches with genetics as a basic science course in the early years of medical school and de-emphasizes clinical relevance of the field. These observations support the notion that further integration is required to move genetics into the clinical curriculum of medical schools and the clinical content of USMLE Step exams.

A Phenotypic Female Adolescent with Primary Amenorrhea and Dysmorphic Features.

We report on a case of a 14-year-old phenotypic female with a microdeletion at 13q31.1-q31.3, dysmorphic facial and limb features, and neurologic symptoms. She presented to her pediatrician with concerns for delayed puberty, and laboratory analysis revealed hypergonadotropic hypogonadism. She was found to have an XY karyotype and streak gonads. Further genetic studies did not reveal another cause for her gonadal dysgenesis and, to our knowledge, an association with her known 13q-microdeletion has not yet been reported. Given the risk of malignancy with XY gonadal dysgenesis, the patient had surgery to remove the gonads and had no postoperative complications after a 6-month follow-up visit. We also discuss the role of the pediatrician in cases of delayed puberty, from initial diagnosis to definitive management. [Pediatr Ann. 2019;48(12):e495-e500.].

A pathogenic CtBP1 missense mutation causes altered cofactor binding and transcriptional activity.

We previously reported a pathogenic de novo p.R342W mutation in the transcriptional corepressor CTBP1 in four independent patients with neurodevelopmental disabilities [1]. Here, we report the clinical phenotypes of seven additional individuals with the same recurrent de novo CTBP1 mutation. Within this cohort, we identified consistent CtBP1-related phenotypes of intellectual disability, ataxia, hypotonia, and tooth enamel defects present in most patients. The R342W mutation in CtBP1 is located within a region implicated in a high affinity-binding cleft for CtBP-interacting proteins. Unbiased proteomic analysis demonstrated reduced interaction of several chromatin-modifying factors with the CtBP1 W342 mutant. Genome-wide transcriptome analysis in human glioblastoma cell lines expressing -CtBP1 R342 (wt) or W342 mutation revealed changes in the expression profiles of genes controlling multiple cellular processes. Patient-derived dermal fibroblasts were found to be more sensitive to apoptosis during acute glucose deprivation compared to controls. Glucose deprivation strongly activated the BH3-only pro-apoptotic gene NOXA, suggesting a link between enhanced cell death and NOXA expression in patient fibroblasts. Our results suggest that context-dependent relief of transcriptional repression of the CtBP1 mutant W342 allele may contribute to deregulation of apoptosis in target tissues of patients leading to neurodevelopmental phenotypes.

Correction: "Congenital hyperinsulinism as the presenting feature of Kabuki syndrome: clinical and molecular characterization of 10 affected individuals".

The author Diva D. De Leon was incorrectly listed as instead of Diva D. De Leó-Critchlow in the original version of this paper.

Targeted exome analysis identifies the genetic basis of disease in over 50% of patients with a wide range of ataxia-related phenotypes.

PURPOSE: To examine the impact of a targeted exome approach for the molecular diagnosis of patients nationwide with a wide range of ataxia-related phenotypes. METHODS: One hundred and seventy patients with ataxia of unknown etiology referred from clinics throughout the United States and Canada were studied using a targeted exome approach. Patients ranged in age from 2 to 88 years. Analysis was focused on 441 curated genes associated with ataxia and ataxia-like conditions. RESULTS: Pathogenic and suspected diagnostic variants were identified in 88 of the 170 patients, providing a positive molecular diagnostic rate of 52%. Forty-six different genes were implicated, with the six most commonly mutated genes being SPG7, SYNE1, ADCK3, CACNA1A, ATP1A3, and SPTBN2, which accounted for >40% of the positive cases. In many cases a diagnosis was provided for conditions that were not suspected and resulted in the broadening of the clinical spectrum of several conditions. CONCLUSION: Exome sequencing with targeted analysis provides a high-yield approach for the genetic diagnosis of ataxia-related conditions. This is the largest targeted exome study performed to date in patients with ataxia and ataxia-like conditions and represents patients with a wide range of ataxia phenotypes typically encountered in neurology and genetics clinics.

Congenital hyperinsulinism as the presenting feature of Kabuki syndrome: clinical and molecular characterization of 9 affected individuals.

PURPOSE: Describe the clinical and molecular findings of patients with Kabuki syndrome (KS) who present with hypoglycemia due to congenital hyperinsulinism (HI), and assess the incidence of KS in patients with HI. METHODS: We documented the clinical features and molecular diagnoses of 9 infants with persistent HI and KS via a combination of sequencing and copy-number profiling methodologies. Subsequently, we retrospectively evaluated 100 infants with HI lacking a genetic diagnosis, for causative variants in KS genes. RESULTS: Molecular diagnoses of KS were established by identification of pathogenic variants in KMT2D (n = 5) and KDM6A (n = 4). Among the 100 infants with HI of unknown genetic etiology, a KS diagnosis was uncovered in one patient. CONCLUSIONS: The incidence of HI among patients with KS may be higher than previously reported, and KS may account for as much as 1% of patients diagnosed with HI. As the recognition of dysmorphic features associated with KS is challenging in the neonatal period, we propose KS should be considered in the differential diagnosis of HI. Since HI in patients with KS is well managed medically, a timely recognition of hyperinsulinemic episodes will improve outcomes, and prevent aggravation of the preexisting mild to moderate intellectual disability in KS.

Yield of additional genetic testing after chromosomal microarray for diagnosis of neurodevelopmental disability and congenital anomalies: a clinical practice resource of the American College of Medical Genetics and Genomics (ACMG).

PURPOSE: Chromosomal microarray (CMA) is recommended as the first-tier test in evaluation of individuals with neurodevelopmental disability and congenital anomalies. CMA may not detect balanced cytogenomic abnormalities or uniparental disomy (UPD), and deletion/duplications and regions of homozygosity may require additional testing to clarify the mechanism and inform accurate counseling. We conducted an evidence review to synthesize data regarding the benefit of additional testing after CMA to inform a genetic diagnosis. METHODS: The review was guided by key questions related to the detection of genomic events that may require additional testing. A PubMed search for original research articles, systematic reviews, and meta-analyses was evaluated from articles published between 1 January 1983 and 31 March 2017. Based on the key questions, articles were retrieved and data extracted in parallel with comparison of results and discussion to resolve discrepancies. Variables assessed included study design and outcomes. RESULTS: A narrative synthesis was created for each question to describe the occurrence of, and clinical significance of, additional diagnostic findings from subsequent testing performed after CMA. CONCLUSION: These findings may be used to assist the laboratory and clinician when making recommendations about additional testing after CMA, as it impacts clinical care, counseling, and diagnosis.

The natural history of phytosterolemia: Observations on its homeostasis.

BACKGROUND AND AIMS: Phytosterolemia is a rare genetic disease caused by mutation of the ABCG5/8 gene. Our aim was to elucidate the natural history and homeostasis of phytosterolemia. METHODS: We analyzed a Hutterite kindred consisting of 21 homozygotes with phytosterolemia assembled over a period of two decades, all of whom carried the ABCG8 S107X mutation and were treated with ezetimibe. RESULTS: Most of these subjects were asymptomatic and devoid of clinical stigmata, and this, since they were ascertained primarily by a process of cascade testing, suggests that, relative to its true prevalence, phytosterolemia is a condition of low morbidity. All subjects have responded well to treatment with ezetimibe. Initial (pre-treatment) and post-ezetimibe levels of cholesterol and sitosterol were measured and percentage changes on ezetimibe were calculated. We found initial levels to be inversely related to subjects' ages as were percentage responses to ezetimibe therapy. There was also a direct correlation between initial levels and percentage responses to ezetimibe. Hence on-treatment levels were very uniform. CONCLUSIONS: This evidence of a link with age leads us to propose that an age-related change in cholesterol and sterol homeostasis occurs at puberty in phytosterolemia and that the change is due to high sterol and/or stanol levels causing feedback inhibition of sterol regulatory element-binding protein (SREBP-2) processing. This would explain the well-documented phenomenon of depressed cholesterol synthesis in phytosterolemia. It is also well-known that LDL-receptor activity is increased, and this feasibly explains reduced LDL levels and consequent reduction of plasma cholesterol and sitosterol levels. Downregulated SREBP-2 processing would be expected to also lower proprotein convertase subtilisin/kexin type 9 (PCSK9) levels and this would explain high LDL-receptor activity. The above state could be termed disrupted homeostasis and the alternative, seen mostly in children and characterized by hypercholesterolemia and hypersterolemia, simple homeostasis.

Pathogenic Variant in ACTB, p.Arg183Trp, Causes Juvenile-Onset Dystonia, Hearing Loss, and Developmental Delay without Midline Malformation.

ACTB encodes the ß-actin, and pathogenic variations in this gene have typically been associated with Baraitser-Winter cerebrofrontofacial syndrome, a congenital malformation syndrome characterized by short stature, craniofacial anomalies, and cerebral anomalies. Here, we describe the third case with the p.Arg183Trp variant in ACTB causing juvenile-onset dystonia. Our patient has severe, intractable dystonia, developmental delay, and sensorineural hearing loss, besides hyperintensities in the caudate nuclei and putamen on the brain MRI, which is a distinct but overlapping phenotype with the previously reported case of identical twins with the same alteration in ACTB.

Synopsis of Guidelines for the Clinical Management of Cerebral Cavernous Malformations: Consensus Recommendations Based on Systematic Literature Review by the Angioma Alliance Scientific Advisory Board Clinical Experts Panel.

BACKGROUND: Despite many publications about cerebral cavernous malformations (CCMs), controversy remains regarding diagnostic and management strategies. OBJECTIVE: To develop guidelines for CCM management. METHODS: The Angioma Alliance ( www.angioma.org ), the patient support group in the United States advocating on behalf of patients and research in CCM, convened a multidisciplinary writing group comprising expert CCM clinicians to help summarize the existing literature related to the clinical care of CCM, focusing on 5 topics: (1) epidemiology and natural history, (2) genetic testing and counseling, (3) diagnostic criteria and radiology standards, (4) neurosurgical considerations, and (5) neurological considerations. The group reviewed literature, rated evidence, developed recommendations, and established consensus, controversies, and knowledge gaps according to a prespecified protocol. RESULTS: Of 1270 publications published between January 1, 1983 and September 31, 2014, we selected 98 based on methodological criteria, and identified 38 additional recent or relevant publications. Topic authors used these publications to summarize current knowledge and arrive at 23 consensus management recommendations, which we rated by class (size of effect) and level (estimate of certainty) according to the American Heart Association/American Stroke Association criteria. No recommendation was level A (because of the absence of randomized controlled trials), 11 (48%) were level B, and 12 (52%) were level C. Recommendations were class I in 8 (35%), class II in 10 (43%), and class III in 5 (22%). CONCLUSION: Current evidence supports recommendations for the management of CCM, but their generally low levels and classes mandate further research to better inform clinical practice and update these recommendations. The complete recommendations document, including the criteria for selecting reference citations, a more detailed justification of the respective recommendations, and a summary of controversies and knowledge gaps, was similarly peer reviewed and is available on line www.angioma.org/CCMGuidelines .

The Effect of the Testis on the Ovary: Structure-Function Relationships in a Neonate with a Unilateral Ovotestis (Ovotesticular Disorder of Sex Development)
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AIMS: To evaluate gonadal function in a newborn with suspected ovotesticular disorder of sex development (DSD). METHODS: Gonadal function was evaluated at baseline and after gonadotropin-releasing hormone agonist (GnRHag) stimulation testing. RESULTS: A full-term 46,XX neonate with genital ambiguity produced serum testosterone and anti-Müllerian hormone (AMH) levels appropriate for males within days, while serum estradiol remained prepubertal, both spontaneously and in response to GnRHag stimulation testing. Ovotesticular DSD was diagnosed at laparoscopy: the left gonad was an ovotestis and the right gonad an ovary arrested at the primordial follicle stage of development. Mosaicism for an isochromosome of the Y short arm in 6-18% of gonadal cells was demonstrated. After ovotestis removal at 3 weeks of age, serum AMH became low within a month, but the elevated testosterone was slow to resolve, apparently from ovarian androgenic hyperfunction coincident with ovarian estrogenic hyperfunction and an adult degree of ovarian development. Ovarian morphology and function gradually normalized as neonatal minipuberty waned. CONCLUSIONS: In a neonate with genital ambiguity due to ovotesticular DSD, testicular AMH and testosterone production respectively appear to account for the initial arrest of ovarian development and subsequent rapid hyperfunction of the contralateral ovary after ovotestis removal.
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Recommendations for the integration of genomics into clinical practice.

The introduction of diagnostic clinical genome and exome sequencing (CGES) is changing the scope of practice for clinical geneticists. Many large institutions are making a significant investment in infrastructure and technology, allowing clinicians to access CGES, especially as health-care coverage begins to extend to clinically indicated genomic sequencing-based tests. Translating and realizing the comprehensive clinical benefits of genomic medicine remain a key challenge for the current and future care of patients. With the increasing application of CGES, it is necessary for geneticists and other health-care providers to understand its benefits and limitations in order to interpret the clinical relevance of genomic variants identified in the context of health and disease. New, collaborative working relationships with specialists across diverse disciplines (e.g., clinicians, laboratorians, bioinformaticians) will undoubtedly be key attributes of the future practice of clinical genetics and may serve as an example for other specialties in medicine. These new skills and relationships will also inform the development of the future model of clinical genetics training curricula. To address the evolving role of the clinical geneticist in the rapidly changing climate of genomic medicine, two Clinical Genetics Think Tank meetings were held that brought together physicians, laboratorians, scientists, genetic counselors, trainees, and patients with experience in clinical genetics, genetic diagnostics, and genetics education. This article provides recommendations that will guide the integration of genomics into clinical practice.Genet Med 18 11, 1075-1084.

A recurrent de novo CTBP1 mutation is associated with developmental delay, hypotonia, ataxia, and tooth enamel defects.

Exome sequencing is an effective way to identify genetic causes of etiologically heterogeneous conditions such as developmental delay and intellectual disabilities. Using exome sequencing, we have identified four patients with similar phenotypes of developmental delay, intellectual disability, failure to thrive, hypotonia, ataxia, and tooth enamel defects who all have the same de novo R331W missense variant in C-terminal binding protein 1 (CTBP1). CTBP1 is a transcriptional regulator critical for development by coordinating different regulatory pathways. The R331W variant found in these patients is within the C-terminal portion of the PLDLS (Pro-Leu-Asp-Leu-Ser) binding cleft, which is the domain through which CTBP1, interacts with chromatin-modifying enzymes and mediates chromatin-dependent gene repression pathways. This is the first report of mutations within CTBP1 in association with any human disease.

BATTEN DISEASE CAUSED BY A NOVEL MUTATION IN THE PPT1 GENE.

PURPOSE: To report a case of Batten disease due to a previously unreported mutation in PPT1. METHODS: A 9-year-old girl presented with classic clinical findings of Batten Disease. RESULTS: Genetic testing for the mutations in the most common Batten disease gene, CLN3, was negative. Evaluation of a panel of genes known to be implicated in neuronal ceroid lipofuscinoses revealed disease causing mutations in PPT1, one of which was novel. CONCLUSION: Mutations in PPT1 typically cause the infantile form of neuronal ceroid lipofuscinosis. Clinical diagnosis of the juvenile form of neuronal ceroid lipofuscinosis, Batten disease, should still be considered in cases with negative CLN3 genetic testing. Batten disease can occur due to genetic heterogeneity. Testing of other members of the neuronal ceroid lipofuscinosis gene family can lead to confirmation of the correct diagnosis.

A Review of Fanconi Anemia for the Practicing Pediatrician.

Early recognition of a patient who might have Fancomi anemia by the general pediatrician and referral to a tertiary care center with a dedicated cancer risk program is critical for early diagnosis. Genetic testing and close multidisciplinary surveillance is required for patients with this syndrome and their families because of its multisystem involvement and propensity for early-onset bone marrow failure and leukemic transformation. This article reviews the clinical symptoms and signs, radiologic findings, and screening guidelines of FA for the general pediatrician.