Genetic Misdiagnoses and the Potential for Health Disparities.

BACKGROUND: For more than a decade, risk stratification for hypertrophic cardiomyopathy has been enhanced by targeted genetic testing. Using sequencing results, clinicians routinely assess the risk of hypertrophic cardiomyopathy in a patient's relatives and diagnose the condition in patients who have ambiguous clinical presentations. However, the benefits of genetic testing come with the risk that variants may be misclassified. METHODS: Using publicly accessible exome data, we identified variants that have previously been considered causal in hypertrophic cardiomyopathy and that are overrepresented in the general population. We studied these variants in diverse populations and reevaluated their initial ascertainments in the medical literature. We reviewed patient records at a leading genetic-testing laboratory for occurrences of these variants during the near-decade-long history of the laboratory. RESULTS: Multiple patients, all of whom were of African or unspecified ancestry, received positive reports, with variants misclassified as pathogenic on the basis of the understanding at the time of testing. Subsequently, all reported variants were recategorized as benign. The mutations that were most common in the general population were significantly more common among black Americans than among white Americans (P<0.001). Simulations showed that the inclusion of even small numbers of black Americans in control cohorts probably would have prevented these misclassifications. We identified methodologic shortcomings that contributed to these errors in the medical literature. CONCLUSIONS: The misclassification of benign variants as pathogenic that we found in our study shows the need for sequencing the genomes of diverse populations, both in asymptomatic controls and the tested patient population. These results expand on current guidelines, which recommend the use of ancestry-matched controls to interpret variants. As additional populations of different ancestry backgrounds are sequenced, we expect variant reclassifications to increase, particularly for ancestry groups that have historically been less well studied. (Funded by the National Institutes of Health.).

The sensitivity of exome sequencing in identifying pathogenic mutations for LGMD in the United States.

The current study characterizes a cohort of limb-girdle muscular dystrophy (LGMD) in the United States using whole-exome sequencing. Fifty-five families affected by LGMD were recruited using an institutionally approved protocol. Exome sequencing was performed on probands and selected parental samples. Pathogenic mutations and cosegregation patterns were confirmed by Sanger sequencing. Twenty-two families (40%) had novel and previously reported pathogenic mutations, primarily in LGMD genes, and also in genes for Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, congenital myopathy, myofibrillar myopathy, inclusion body myopathy and Pompe disease. One family was diagnosed via clinical testing. Dominant mutations were identified in COL6A1, COL6A3, FLNC, LMNA, RYR1, SMCHD1 and VCP, recessive mutations in ANO5, CAPN3, GAA, LAMA2, SGCA and SGCG, and X-linked mutations in DMD. A previously reported variant in DMD was confirmed to be benign. Exome sequencing is a powerful diagnostic tool for LGMD. Despite careful phenotypic screening, pathogenic mutations were found in other muscle disease genes, largely accounting for the increased sensitivity of exome sequencing. Our experience suggests that broad sequencing panels are useful for these analyses because of the phenotypic overlap of many neuromuscular conditions. The confirmation of a benign DMD variant illustrates the potential of exome sequencing to help determine pathogenicity.

Will disruptive mood dysregulation disorder reduce false diagnosis of bipolar disorder in children?

OBJECTIVES: The frequency of diagnosis of bipolar disorder has risen dramatically in children and adolescents. The DSM-V Work Group has suggested a new diagnosis termed disruptive mood dysregulation disorder (DMDD) (formerly temper dysregulation disorder with dysphoria) to reduce the rate of false diagnosis of bipolar disorder in young people. We sought to determine if the application of the proposed diagnostic criteria for DMDD would reduce the rate of diagnosis of bipolar disorder in children. PATIENTS AND METHODS: Eighty-two consecutively hospitalized children, ages 5 to 12 years, on a children's inpatient unit were rigorously diagnosed using admission interviews of the parents and the child, rating scales, and observation over the course of hospitalization. RESULTS: Overall, 30.5% of inpatient children met criteria for DMDD by parent report, and 15.9% by inpatient unit observation. Fifty-six percent of inpatient children had parent-reported manic symptoms. Of those, 45.7% met criteria for DMDD by parent-report, though only 17.4% did when observed on the inpatient unit. CONCLUSION: Although DMDD does decrease the rate of diagnosis of bipolar disorder in children, how much depends on whether history or observation is used.

Stepped Treatment for Attention-Deficit/Hyperactivity Disorder and Aggressive Behavior: A Randomized, Controlled Trial of Adjunctive Risperidone, Divalproex Sodium, or Placebo After Stimulant Medication Optimization.

OBJECTIVE: Stimulant medications are the most prevalent first-line pharmacotherapy for attention-deficit/hyperactivity disorder, but children with aggressive behavior often receive multiagent treatment. There is sparse evidence for the benefits of adjunctive medications when stimulant monotherapy provides inadequate benefit for aggressive behavior, yet the adverse effects of common adjuncts are well established. This study compared the efficacy in reducing aggressive behavior of risperidone (RISP), divalproex sodium (DVPX), and placebo (PBO) added to stimulant medication among childrenwhose symptoms persisted after individually optimized stimulant treatment. METHOD: This trial enrolled 6- to 12-year-old with attention-deficit/hyperactivity disorder, a disruptive disorder, significant aggressive behavior, and prior stimulant treatment. Open, systematically titrated stimulant treatment identified patients with inadequate reductions in aggressive behavior, who were then randomly assigned to receive adjunctive RISP, DVPX, or PBO under double-blinded conditions for 8 weeks. Family-based behavioral treatment was offered throughout the trial. The primary outcome was the parent-completed Retrospective Modified Overt Aggression Scale. RESULTS: Participants included 175 children (mean [SD] age 9.48 [2.04] years, 19% female). Of participants, 151 completed the stimulant optimization phase, with aggression remitting among 96 (63%), and 45 were randomly assigned to adjunctive treatment groups. The adjunctive RISP group showed greater reductions in aggression ratings than the PBO group (least squares means difference [ΔLSM], -2.33; 95% CI, -3.83 to -0.82; effect size [ES], -1.32), as did the DVPX group (ΔLSM, -1.60; 95% CI, -3.18 to -0.03; ES, -0.91). Mean standardized body mass index scores increased more among RISP-treated participants than participants receiving PBO (ΔLSM, 1.54; 95% CI, 0.68 to 2.40; ES, 0.58). CONCLUSION: High response rate during the trial's open stimulant optimization phase suggests that rigorous titration of stimulant medication and concurrent behavioral therapy may avert the need for additional medications. Among nonremitters, RISP and DVPX were efficacious adjunctive treatments, although RISP was associated with weight gain. CLINICAL TRIAL REGISTRATION INFORMATION: Effectiveness of Combined Medication Treatment for Aggression in Children With Attention Deficit With Hyperactivity Disorder (The SPICY Study); https://www.clinicaltrials.gov; NCT00794625.

Prevalence and Treatment Outcomes of Persistent Negative Mood Among Children with Attention-Deficit/Hyperactivity Disorder and Aggressive Behavior.

OBJECTIVE: Diagnostic criteria for disruptive mood dysregulation disorder (DMDD) require 1) periodic rageful outbursts and 2) disturbed mood (anger or irritability) that persists most of the time in between outbursts. Stimulant monotherapy, methodically titrated, often culminates in remission of severe aggressive behavior, but it is unclear whether those with persistent mood symptoms benefit less.This study examined the association between the presence of persistent mood disturbances and treatment outcomes among children with attention-deficit/hyperactivity disorder (ADHD) and periodic aggressive, rageful outbursts. METHODS: Within a cohort of children with ADHD and aggressive behavior (n = 156), the prevalence of persistent mood symptoms was evaluated at baseline and after completion of a treatment protocol that provided stimulant monotherapy and family-based behavioral treatment (duration mean [SD] = 70.04 [37.83] days). The relationship of persistent mood symptoms on posttreatment aggressive behavior was assessed, as well as changes in mood symptoms. RESULTS: Aggressive behavior and periodic rageful outbursts remitted among 51% of the participants. Persistent mood symptoms at baseline did not affect the odds that aggressive behavior would remit during treatment. Reductions in symptoms of sustained mood disturbance accompanied reductions in periodic outbursts. Children who at baseline had high irritability but low depression ratings showed elevated aggression scores at baseline and after treatment; however, they still displayed large reductions in aggression. CONCLUSIONS: Among aggressive children with ADHD, aggressive behaviors are just as likely to decrease following stimulant monotherapy and behavioral treatment among those with sustained mood symptoms and those without. Improvements in mood problems are evident as well. Therefore, the abnormalities in persistent mood described by DMDD's criteria do not contraindicate stimulant therapy as initial treatment among those with comorbid ADHD. Rather, substantial improvements may be anticipated, and remission of both behavioral and mood symptoms seems achievable for a proportion of patients. TRIAL REGISTRATION: ClinicalTrials.gov (U.S.); IDs: NCT00228046 and NCT00794625; www.clinicaltrials.gov.

Gene expression analysis in Fmr1KO mice identifies an immunological signature in brain tissue and mGluR5-related signaling in primary neuronal cultures.

BACKGROUND: Fragile X syndrome (FXS) is a neurodevelopmental disorder whose biochemical manifestations involve dysregulation of mGluR5-dependent pathways, which are widely modeled using cultured neurons. In vitro phenotypes in cultured neurons using standard morphological, functional, and chemical approaches have demonstrated considerable variability. Here, we study transcriptomes obtained in situ in the intact brain tissues of a murine model of FXS to see how they reflect the in vitro state. METHODS: We used genome-wide mRNA expression profiling as a robust characterization tool for studying differentially expressed pathways in fragile X mental retardation 1 (Fmr1) knockout (KO) and wild-type (WT) murine primary neuronal cultures and in embryonic hippocampal and cortical murine tissue. To study the developmental trajectory and to relate mouse model data to human data, we used an expression map of human development to plot murine differentially expressed genes in KO/WT cultures and brain. RESULTS: We found that transcriptomes from cell cultures showed a stronger signature of Fmr1KO than whole tissue transcriptomes. We observed an over-representation of immunological signaling pathways in embryonic Fmr1KO cortical and hippocampal tissues and over-represented mGluR5-downstream signaling pathways in Fmr1KO cortical and hippocampal primary cultures. Genes whose expression was up-regulated in Fmr1KO murine cultures tended to peak early in human development, whereas differentially expressed genes in embryonic cortical and hippocampal tissues clustered with genes expressed later in human development. CONCLUSIONS: The transcriptional profile in brain tissues primarily centered on immunological mechanisms, whereas the profiles from cell cultures showed defects in neuronal activity. We speculate that the isolation and culturing of neurons caused a shift in neurological transcriptome towards a "juvenile" or "de-differentiated" state. Moreover, cultured neurons lack the close coupling with glia that might be responsible for the immunological phenotype in the intact brain. Our results suggest that cultured cells may recapitulate an early phase of the disease, which is also less obscured with a consequent "immunological" phenotype and in vivo compensatory mechanisms observed in the embryonic brain. Together, these results suggest that the transcriptome of cultured primary neuronal cells, in comparison to whole brain tissue, more robustly demonstrated the difference between Fmr1KO and WT mice and might reveal a molecular phenotype, which is typically hidden by compensatory mechanisms present in vivo. Moreover, cultures might be useful for investigating the perturbed pathways in early human brain development and genes previously implicated in autism.

An assessment of clinician and researcher needs for support in the era of genomic medicine.

AIM: To assess clinicians' and researchers' past, current and anticipated future use of next-generation sequencing (NGS) and anticipated needs for support. Materials & methods: A web-based survey was conducted at Boston Children's Hospital. RESULTS: Many clinicians anticipate that they will use exome/genome sequencing (44.8%) and/or candidate gene panels (50%) within the next year. Researcher respondents anticipate the need for exome/genome sequencing (48.0%) and candidate gene panels (31.8%). Few respondents (13.6%) said that they felt 'Completely Ready' or 'Pretty Much Ready' to incorporate NGS into their clinical practice or research. CONCLUSION: Researchers and clinicians anticipate increased utilization of NGS. Respondents indicated varying degrees of need for a diverse list of support services, ranking interpretation and clinical correlation support as the most needed services.

iPSC-derived neurons as a higher-throughput readout for autism: promises and pitfalls.

The elucidation of disease etiologies and establishment of robust, scalable, high-throughput screening assays for autism spectrum disorders (ASDs) have been impeded by both inaccessibility of disease-relevant neuronal tissue and the genetic heterogeneity of the disorder. Neuronal cells derived from induced pluripotent stem cells (iPSCs) from autism patients may circumvent these obstacles and serve as relevant cell models. To date, derived cells are characterized and screened by assessing their neuronal phenotypes. These characterizations are often etiology-specific or lack reproducibility and stability. In this review, we present an overview of efforts to study iPSC-derived neurons as a model for autism, and we explore the plausibility of gene expression profiling as a reproducible and stable disease marker.

Callous-unemotional traits, proactive aggression, and treatment outcomes of aggressive children with attention-deficit/hyperactivity disorder.

OBJECTIVE: Stimulant treatment improves impulse control among children with attention-deficit/hyperactivity disorder (ADHD). Decreased aggression often accompanies stimulant pharmacotherapy, suggesting that impulsiveness is integral to aggressive behavior in these children. However, children with high callous-unemotional (CU) traits and proactive aggression may benefit less from ADHD pharmacotherapy, because their aggressive behavior seems more purposeful and deliberate. This study's objective was to determine whether pretreatment CU traits and proactive aggression affect treatment outcomes among aggressive children with ADHD receiving stimulant monotherapy. METHOD: We implemented a stimulant optimization protocol with 160 children 6 to 13 years of age (mean [SD] age of 9.31 [2.02] years; 78.75% male) with ADHD, oppositional defiant or conduct disorder, and significant aggressive behavior. Family-focused behavioral intervention was provided concurrently. The primary outcome was the Retrospective Modified Overt Aggression Scale. The Antisocial Process Screening Device and the Aggression Scale, also completed by parents, measured CU traits and proactive aggression, respectively. Analyses examined moderating effects of CU traits and proactive aggression on outcomes. RESULTS: In all, 82 children (51%) experienced remission of aggressive behavior. Neither CU traits nor proactive aggression predicted remission (CU traits: odds ratio [OR] = 0.94, 95% CI = 0.80-1.11; proactive aggression, OR = 1.05, 95% CI = 0.86-1.29). Children whose overall aggression remitted showed decreases in CU traits (effect size = -0.379, 95% CI = -0.60 to -0.16) and proactive aggression (effect size = -0.463, 95% CI = -0.69 to -0.23). CONCLUSIONS: Findings suggest that pretreatment CU traits and proactive aggression do not forecast worse outcomes for aggressive children with ADHD receiving optimized stimulant pharmacotherapy. With such treatment, CU traits and proactive aggression may decline alongside other behavioral improvements. Clinical trial registration information--Medication Strategies for Treating Aggressive Behavior in Youth With Attention Deficit Hyperactivity Disorder; http://clinicaltrials.gov/; NCT00228046; and Effectiveness of Combined Medication Treatment for Aggression in Children With Attention Deficit With Hyperactivity Disorder (The SPICY Study); http://clinicaltrials.gov/; NCT00794625.

Mutation of KCNJ8 in a patient with Cantú syndrome with unique vascular abnormalities - support for the role of K(ATP) channels in this condition.

KCNJ8 (NM_004982) encodes the pore forming subunit of one of the ATP-sensitive inwardly rectifying potassium (KATP) channels. KCNJ8 sequence variations are traditionally associated with J-wave syndromes, involving ventricular fibrillation and sudden cardiac death. Recently, the KATP gene ABCC9 (SUR2, NM_020297) has been associated with the multi-organ disorder Cantú syndrome or hypertrichotic osteochondrodysplasia (MIM 239850) (hypertrichosis, macrosomia, osteochondrodysplasia, and cardiomegaly). Here, we report on a patient with a de novo nonsynonymous KCNJ8 SNV (p.V65M) and Cantú syndrome, who tested negative for mutations in ABCC9. The genotype and multi-organ abnormalities of this patient are reviewed. A careful screening of the KATP genes should be performed in all individuals diagnosed with Cantú syndrome and no mutation in ABCC9.