Mono-allelic KCNB2 variants lead to a neurodevelopmental syndrome caused by altered channel inactivation.

Ion channels mediate voltage fluxes or action potentials that are central to the functioning of excitable cells such as neurons. The KCNB family of voltage-gated potassium channels (Kv) consists of two members (KCNB1 and KCNB2) encoded by KCNB1 and KCNB2, respectively. These channels are major contributors to delayed rectifier potassium currents arising from the neuronal soma which modulate overall excitability of neurons. In this study, we identified several mono-allelic pathogenic missense variants in KCNB2, in individuals with a neurodevelopmental syndrome with epilepsy and autism in some individuals. Recurrent dysmorphisms included a broad forehead, synophrys, and digital anomalies. Additionally, we selected three variants where genetic transmission has not been assessed, from two epilepsy studies, for inclusion in our experiments. We characterized channel properties of these variants by expressing them in oocytes of Xenopus laevis and conducting cut-open oocyte voltage clamp electrophysiology. Our datasets indicate no significant change in absolute conductance and conductance-voltage relationships of most disease variants as compared to wild type (WT), when expressed either alone or co-expressed with WT-KCNB2. However, variants c.1141A>G (p.Thr381Ala) and c.641C>T (p.Thr214Met) show complete abrogation of currents when expressed alone with the former exhibiting a left shift in activation midpoint when expressed alone or with WT-KCNB2. The variants we studied, nevertheless, show collective features of increased inactivation shifted to hyperpolarized potentials. We suggest that the effects of the variants on channel inactivation result in hyper-excitability of neurons, which contributes to disease manifestations.

Heterozygous Variants in KDM4B Lead to Global Developmental Delay and Neuroanatomical Defects.

KDM4B is a lysine-specific demethylase with a preferential activity on H3K9 tri/di-methylation (H3K9me3/2)-modified histones. H3K9 tri/di-demethylation is an important epigenetic mechanism responsible for silencing of gene expression in animal development and cancer. However, the role of KDM4B on human development is still poorly characterized. Through international data sharing, we gathered a cohort of nine individuals with mono-allelic de novo or inherited variants in KDM4B. All individuals presented with dysmorphic features and global developmental delay (GDD) with language and motor skills most affected. Three individuals had a history of seizures, and four had anomalies on brain imaging ranging from agenesis of the corpus callosum with hydrocephalus to cystic formations, abnormal hippocampi, and polymicrogyria. In mice, lysine demethylase 4B is expressed during brain development with high levels in the hippocampus, a region important for learning and memory. To understand how KDM4B variants can lead to GDD in humans, we assessed the effect of KDM4B disruption on brain anatomy and behavior through an in vivo heterozygous mouse model (Kdm4b+/-), focusing on neuroanatomical changes. In mutant mice, the total brain volume was significantly reduced with decreased size of the hippocampal dentate gyrus, partial agenesis of the corpus callosum, and ventriculomegaly. This report demonstrates that variants in KDM4B are associated with GDD/ intellectual disability and neuroanatomical defects. Our findings suggest that KDM4B variation leads to a chromatinopathy, broadening the spectrum of this group of Mendelian disorders caused by alterations in epigenetic machinery.

A novel DPH5-related diphthamide-deficiency syndrome causing embryonic lethality or profound neurodevelopmental disorder.

PURPOSE: Diphthamide is a post-translationally modified histidine essential for messenger RNA translation and ribosomal protein synthesis. We present evidence for DPH5 as a novel cause of embryonic lethality and profound neurodevelopmental delays (NDDs). METHODS: Molecular testing was performed using exome or genome sequencing. A targeted Dph5 knockin mouse (C57BL/6Ncrl-Dph5em1Mbp/Mmucd) was created for a DPH5 p.His260Arg homozygous variant identified in 1 family. Adenosine diphosphate-ribosylation assays in DPH5-knockout human and yeast cells and in silico modeling were performed for the identified DPH5 potential pathogenic variants. RESULTS: DPH5 variants p.His260Arg (homozygous), p.Asn110Ser and p.Arg207Ter (heterozygous), and p.Asn174LysfsTer10 (homozygous) were identified in 3 unrelated families with distinct overlapping craniofacial features, profound NDDs, multisystem abnormalities, and miscarriages. Dph5 p.His260Arg homozygous knockin was embryonically lethal with only 1 subviable mouse exhibiting impaired growth, craniofacial dysmorphology, and multisystem dysfunction recapitulating the human phenotype. Adenosine diphosphate-ribosylation assays showed absent to decreased function in DPH5-knockout human and yeast cells. In silico modeling of the variants showed altered DPH5 structure and disruption of its interaction with eEF2. CONCLUSION: We provide strong clinical, biochemical, and functional evidence for DPH5 as a novel cause of embryonic lethality or profound NDDs with multisystem involvement and expand diphthamide-deficiency syndromes and ribosomopathies.

Heterozygous loss-of-function variants significantly expand the phenotypes associated with loss of GDF11.

PURPOSE: Growth differentiation factor 11 (GDF11) is a key signaling protein required for proper development of many organ systems. Only one prior study has associated an inherited GDF11 variant with a dominant human disease in a family with variable craniofacial and vertebral abnormalities. Here, we expand the phenotypic spectrum associated with GDF11 variants and document the nature of the variants. METHODS: We present a cohort of six probands with de novo and inherited nonsense/frameshift (4/6 patients) and missense (2/6) variants in GDF11. We generated gdf11 mutant zebrafish to model loss of gdf11 phenotypes and used an overexpression screen in Drosophila to test variant functionality. RESULTS: Patients with variants in GDF11 presented with craniofacial (5/6), vertebral (5/6), neurological (6/6), visual (4/6), cardiac (3/6), auditory (3/6), and connective tissue abnormalities (3/6). gdf11 mutant zebrafish show craniofacial abnormalities and body segmentation defects that match some patient phenotypes. Expression of the patients' variants in the fly showed that one nonsense variant in GDF11 is a severe loss-of-function (LOF) allele whereas the missense variants in our cohort are partial LOF variants. CONCLUSION: GDF11 is needed for human development, particularly neuronal development, and LOF GDF11 alleles can affect the development of numerous organs and tissues.

Prospective, phenotype-driven selection of critically ill neonates for rapid exome sequencing is associated with high diagnostic yield.

PURPOSE: To investigate the impact of rapid-turnaround exome sequencing in critically ill neonates using phenotype-based subject selection criteria. METHODS: Intensive care unit babies aged <6 months with hypotonia, seizures, a complex metabolic phenotype, and/or multiple congenital malformations were prospectively enrolled for rapid (<7 day) trio-based exome sequencing. Genomic variants relevant to the presenting phenotype were returned to the medical team. RESULTS: A genetic diagnosis was attained in 29 of 50 (58%) sequenced cases. Twenty-seven (54%) patients received a molecular diagnosis involving known disease genes; two additional cases (4%) were solved with pathogenic variants found in novel disease genes. In 24 of the solved cases, diagnosis had impact on patient management and/or family members. Management changes included shift to palliative care, medication changes, involvement of additional specialties, and the consideration of new experimental therapies. CONCLUSION: Phenotype-based patient selection is effective at identifying critically ill neonates with a high likelihood of receiving a molecular diagnosis via rapid-turnaround exome sequencing, leading to faster and more accurate diagnoses, reducing unnecessary testing and procedures, and informing medical care.

Updating the neurodevelopmental profile of Alazami syndrome: Illustrating the role of developmental assessment in rare genetic disorders.

Alazami syndrome, caused by biallelic pathogenic variants in LARP7, is a recently-described rare genetic disorder, with 17 patients currently reported in the literature. We present a case of a male infant referred for genetics evaluation at 5 months of age, found at 17 months of age to have Alazami syndrome. He was promptly referred for developmental evaluation, where he was found to be higher functioning than prior reports of individuals with this condition. This demonstrates the neurodevelopmental phenotypic variability seen in rare genetic disorders; it also demonstrates the important role of developmental programs to measure and track outcomes and provide support for infants with genetic disorders that put them at risk of developmental disabilities.

Yield of whole exome sequencing in undiagnosed patients facing insurance coverage barriers to genetic testing.

BACKGROUND: Despite growing evidence of diagnostic yield and clinical utility of whole exome sequencing (WES) in patients with undiagnosed diseases, there remain significant cost and reimbursement barriers limiting access to such testing. The diagnostic yield and resulting clinical actions of WES for patients who previously faced insurance coverage barriers have not yet been explored. METHODS: We performed a retrospective descriptive analysis of clinical WES outcomes for patients facing insurance coverage barriers prior to clinical WES and who subsequently enrolled in the Undiagnosed Diseases Network (UDN). Clinical WES was completed as a result of participation in the UDN. Payer type, molecular diagnostic yield, and resulting clinical actions were evaluated. RESULTS: Sixty-six patients in the UDN faced insurance coverage barriers to WES at the time of enrollment (67% public payer, 26% private payer). Forty-two of 66 (64%) received insurance denial for clinician-ordered WES, 19/66 (29%) had health insurance through a payer known not to cover WES, and 5/66 (8%) had previous payer denial of other genetic tests. Clinical WES results yielded a molecular diagnosis in 23 of 66 patients (35% [78% pediatric, 65% neurologic indication]). Molecular diagnosis resulted in clinical actions in 14 of 23 patients (61%). CONCLUSIONS: These data demonstrate that a substantial proportion of patients who encountered insurance coverage barriers to WES had a clinically actionable molecular diagnosis, supporting the notion that WES has value as a covered benefit for patients who remain undiagnosed despite objective clinical findings.

Mutations in PYCR2, Encoding Pyrroline-5-Carboxylate Reductase 2, Cause Microcephaly and Hypomyelination.

Despite recent advances in understanding the genetic bases of microcephaly, a large number of cases of microcephaly remain unexplained, suggesting that many microcephaly syndromes and associated genes have yet to be identified. Here, we report mutations in PYCR2, which encodes an enzyme in the proline biosynthesis pathway, as the cause of a unique syndrome characterized by postnatal microcephaly, hypomyelination, and reduced cerebral white-matter volume. Linkage mapping and whole-exome sequencing identified homozygous mutations (c.355C>T [p.Arg119Cys] and c.751C>T [p.Arg251Cys]) in PYCR2 in the affected individuals of two consanguineous families. A lymphoblastoid cell line from one affected individual showed a strong reduction in the amount of PYCR2. When mutant cDNAs were transfected into HEK293FT cells, both variant proteins retained normal mitochondrial localization but had lower amounts than the wild-type protein, suggesting that the variant proteins were less stable. A PYCR2-deficient HEK293FT cell line generated by genome editing with the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 system showed that PYCR2 loss of function led to decreased mitochondrial membrane potential and increased susceptibility to apoptosis under oxidative stress. Morpholino-based knockdown of a zebrafish PYCR2 ortholog, pycr1b, recapitulated the human microcephaly phenotype, which was rescued by wild-type human PYCR2 mRNA, but not by mutant mRNAs, further supporting the pathogenicity of the identified variants. Hypomyelination and the absence of lax, wrinkly skin distinguishes this condition from that caused by previously reported mutations in the gene encoding PYCR2's isozyme, PYCR1, suggesting a unique and indispensable role for PYCR2 in the human CNS during development.

Pulmonary Vasculopathy Associated with FIGF Gene Mutation.

Vascular endothelial growth factor (VEGF)-D is capable of inducing angiogenesis and lymphangiogenesis through signaling via VEGF receptor (VEGFR)-2 and VEGFR-3, respectively. Mutations in the FIGF (c-fos-induced growth factor) gene encoding VEGF-D have not been reported previously. We describe a young male with a hemizygous mutation in the X-chromosome gene FIGF (c.352 G>A) associated with early childhood respiratory deficiency. Histologically, lungs showed ectatic pulmonary arteries and pulmonary veins. The mutation resulted in a substitution of valine to methionine at residue 118 of the VEGF-D protein. The resultant mutant protein had increased dimerization, induced elevated VEGFR-2 signaling, and caused aberrant angiogenesis in vivo. Our observations characterize a new subtype of congenital diffuse lung disease, provide a histological correlate, and support a critical role for VEGF-D in lung vascular development and homeostasis.

Utility of Genetic Testing in Fetal Alcohol Spectrum Disorder.

OBJECTIVE: To study the utility of genetic evaluation and testing in patients with suspected fetal alcohol spectrum disorder (FASD). STUDY DESIGN: We performed a retrospective chart review of all patients (n = 36) referred for evaluation for suspected FASD to the genetics clinic at Boston Children's Hospital between January 2006 and January 2013. Records of all patients were reviewed to obtain the medical history, family history, examination findings, and investigations, including genetic testing. RESULTS: Of the 36 patients, definite prenatal exposure was documented in 69%. Eight patients did not fulfill clinical criteria for FASD. Chromosomal microarray analysis (CMA) detected 19 copy number variants (CNVs) in 14 patients. Among patients who fulfilled criteria for FASD and underwent CMA, pathogenic CNVs were detected in 3 patients (2q37del, 22q11.22dup, and 4q31.21del syndromes), giving a yield of 14.3%. All 3 patients had overlapping features between FASD and the genetic syndrome. CONCLUSION: Genetic testing, especially CMA, should be considered in patients referred for evaluation of FASD, as a significant proportion have a clinically significant CNV even when they fulfill diagnostic criteria for FASD spectrum.

Genetic and phenotypic dissection of 1q43q44 microdeletion syndrome and neurodevelopmental phenotypes associated with mutations in ZBTB18 and HNRNPU.

Subtelomeric 1q43q44 microdeletions cause a syndrome associating intellectual disability, microcephaly, seizures and anomalies of the corpus callosum. Despite several previous studies assessing genotype-phenotype correlations, the contribution of genes located in this region to the specific features of this syndrome remains uncertain. Among those, three genes, AKT3, HNRNPU and ZBTB18 are highly expressed in the brain and point mutations in these genes have been recently identified in children with neurodevelopmental phenotypes. In this study, we report the clinical and molecular data from 17 patients with 1q43q44 microdeletions, four with ZBTB18 mutations and seven with HNRNPU mutations, and review additional data from 37 previously published patients with 1q43q44 microdeletions. We compare clinical data of patients with 1q43q44 microdeletions with those of patients with point mutations in HNRNPU and ZBTB18 to assess the contribution of each gene as well as the possibility of epistasis between genes. Our study demonstrates that AKT3 haploinsufficiency is the main driver for microcephaly, whereas HNRNPU alteration mostly drives epilepsy and determines the degree of intellectual disability. ZBTB18 deletions or mutations are associated with variable corpus callosum anomalies with an incomplete penetrance. ZBTB18 may also contribute to microcephaly and HNRNPU to thin corpus callosum, but with a lower penetrance. Co-deletion of contiguous genes has additive effects. Our results confirm and refine the complex genotype-phenotype correlations existing in the 1qter microdeletion syndrome and define more precisely the neurodevelopmental phenotypes associated with genetic alterations of AKT3, ZBTB18 and HNRNPU in humans.

Musculoskeletal Conditions in a Pediatric Population with Ehlers-Danlos Syndrome.

OBJECTIVE: To describe musculoskeletal conditions in children with Ehlers-Danlos syndrome (EDS). STUDY DESIGN: A retrospective medical record review was performed, which evaluated 205 patients with EDS (ages 6-19 years) seen in sports medicine or orthopedic clinic at a large pediatric hospital over a 5-year period. RESULTS: Female (n = 147) and male (n = 57) patients were identified (mean age 12.7 years). The most common EDS subtype (55.6%) was hypermobility type. Patients had between 1 and 69 visits (median 4), and 764 diagnoses were recorded, most commonly laxity/instability, pain, subluxation, and scoliosis/spinal asymmetry. Nearly one-half of patients (46.8%) received a general diagnosis of pain because no more specific cause was identified, in addition to 8.3% who were diagnosed with chronic pain syndrome. The most common sites of presenting issue were knee (43.4%), back (32.2%), and shoulder (31.2%). Over three-fourths (77.1%) of patients had imaging. Most (88.1%) were prescribed physical therapy and/or other conservative measures, such as rest (40.5%), orthotics (35.6%), and medication (32.2%). Surgery was recommended to 28.8% of the study population. CONCLUSIONS: Many pediatric and adolescent patients with EDS experience joint pain, instability, and scoliosis, along with other musculoskeletal issues. Despite extensive workup, the etiology of pain may not be identified. Large numbers of office visits, imaging studies, treatment prescriptions, and specialist referrals indicate considerable use of medical resources and highlight a great need for injury prevention and additional study.

Novel loss-of-function variants in DIAPH1 associated with syndromic microcephaly, blindness, and early onset seizures.

Exome sequencing identified homozygous loss-of-function variants in DIAPH1 (c.2769delT; p.F923fs and c.3145C>T; p.R1049X) in four affected individuals from two unrelated consanguineous families. The affected individuals in our report were diagnosed with postnatal microcephaly, early-onset epilepsy, severe vision impairment, and pulmonary symptoms including bronchiectasis and recurrent respiratory infections. A heterozygous DIAPH1 mutation was originally reported in one family with autosomal dominant deafness. Recently, however, a homozygous nonsense DIAPH1 mutation (c.2332C4T; p.Q778X) was reported in five siblings in a single family affected by microcephaly, blindness, early onset seizures, developmental delay, and bronchiectasis. The role of DIAPH1 was supported using parametric linkage analysis, RNA and protein studies in their patients' cell lines and further studies in human neural progenitors cells and a diap1 knockout mouse. In this report, the proband was initially brought to medical attention for profound metopic synostosis. Additional concerns arose when his head circumference did not increase after surgical release at 5 months of age and he was diagnosed with microcephaly and epilepsy at 6 months of age. Clinical exome analysis identified a homozygous DIAPH1 mutation. Another homozygous DIAPH1 mutation was identified in the research exome analysis of a second family with three siblings presenting with a similar phenotype. Importantly, no hearing impairment is reported in the homozygous affected individuals or in the heterozygous carrier parents in any of the families demonstrating the autosomal recessive microcephaly phenotype. These additional families provide further evidence of the likely causal relationship between DIAPH1 mutations and a neurodevelopmental disorder.

Mutations in FKBP10, which result in Bruck syndrome and recessive forms of osteogenesis imperfecta, inhibit the hydroxylation of telopeptide lysines in bone collagen.

Although biallelic mutations in non-collagen genes account for <10% of individuals with osteogenesis imperfecta, the characterization of these genes has identified new pathways and potential interventions that could benefit even those with mutations in type I collagen genes. We identified mutations in FKBP10, which encodes the 65 kDa prolyl cis-trans isomerase, FKBP65, in 38 members of 21 families with OI. These include 10 families from the Samoan Islands who share a founder mutation. Of the mutations, three are missense; the remainder either introduce premature termination codons or create frameshifts both of which result in mRNA instability. In four families missense mutations result in loss of most of the protein. The clinical effects of these mutations are short stature, a high incidence of joint contractures at birth and progressive scoliosis and fractures, but there is remarkable variability in phenotype even within families. The loss of the activity of FKBP65 has several effects: type I procollagen secretion is slightly delayed, the stabilization of the intact trimer is incomplete and there is diminished hydroxylation of the telopeptide lysyl residues involved in intermolecular cross-link formation in bone. The phenotype overlaps with that seen with mutations in PLOD2 (Bruck syndrome II), which encodes LH2, the enzyme that hydroxylates the telopeptide lysyl residues. These findings define a set of genes, FKBP10, PLOD2 and SERPINH1, that act during procollagen maturation to contribute to molecular stability and post-translational modification of type I procollagen, without which bone mass and quality are abnormal and fractures and contractures result.

Copy number variation plays an important role in clinical epilepsy.

OBJECTIVE: To evaluate the role of copy number abnormalities detectable using chromosomal microarray (CMA) testing in patients with epilepsy at a tertiary care center. METHODS: We identified patients with International Classification of Diseases, ninth revision (ICD-9) codes for epilepsy or seizures and clinical CMA testing performed between October 2006 and February 2011 at Boston Children's Hospital. We reviewed medical records and included patients who met criteria for epilepsy. We phenotypically characterized patients with epilepsy-associated abnormalities on CMA. RESULTS: Of 973 patients who had CMA and ICD-9 codes for epilepsy or seizures, 805 patients satisfied criteria for epilepsy. We observed 437 copy number variants (CNVs) in 323 patients (1-4 per patient), including 185 (42%) deletions and 252 (58%) duplications. Forty (9%) were confirmed de novo, 186 (43%) were inherited, and parental data were unavailable for 211 (48%). Excluding full chromosome trisomies, CNV size ranged from 18kb to 142Mb, and 34% were >500kb. In at least 40 cases (5%), the epilepsy phenotype was explained by a CNV, including 29 patients with epilepsy-associated syndromes and 11 with likely disease-associated CNVs involving epilepsy genes or "hotspots." We observed numerous recurrent CNVs including 10 involving loss or gain of Xp22.31, a region described in patients with and without epilepsy. INTERPRETATION: Copy number abnormalities play an important role in patients with epilepsy. Because the diagnostic yield of CMA for epilepsy patients is similar to the yield in autism spectrum disorders and in prenatal diagnosis, for which published guidelines recommend testing with CMA, we recommend the implementation of CMA in the evaluation of unexplained epilepsy.

Clinical utility of a next generation sequencing panel assay for Marfan and Marfan-like syndromes featuring aortopathy.

Aortopathy can be defined as aortic dilation, aneurysm, dissection, and tortuosity. Familial aortopathy may occur secondary to fibrillin-1 (FBN1) mutations in the setting of Marfan syndrome, or may occur as a result of other genetic defects with different, but occasionally overlapping, phenotypes. Because of the phenotypic overlap and genetic heterogeneity of disorders featuring aortopathy, we developed a next generation sequencing (NGS) assay and comparative genomic hybridization (CGH) array to detect mutations in 10 genes that cause thoracic aortic aneurysms (TAAs). Here, we report on the clinical and molecular findings in 175 individuals submitted for aortopathy panel testing at ARUP laboratories. Ten genes associated with heritable aortopathies were targeted using hybridization capture prior to sequencing. NGS results were analyzed, and variants were confirmed using Sanger sequencing. Array CGH was used to detect copy-number variation. Of 175 individuals, 18 had a pathogenic mutation and 32 had a variant of uncertain significance (VUS). Most pathogenic mutations (72%) were identified in FBN1. A novel large SMAD3 duplication and FBN1 deletion were identified. Over half who had TAAs or other aortic involvement tested negative for a mutation, suggesting that additional aortopathy genes exist. We anticipate that the clinical sensitivity of at least 10.3% will rise with VUS reclassification and as additional genes are identified and included in the panel. The aortopathy NGS panel aids in the timely molecular diagnosis of individuals with disorders featuring aortopathy and guides proper treatment.

Progressive Postnatal Pansynostosis.

OBJECTIVE: To describe the subtle clinical features, genetic considerations, and management of progressive postnatal pansynostosis, a rare form of multisutural craniosynostosis that insidiously occurs after birth and causes inconspicuous cranial changes. Design, Participants, Setting : The study is a retrospective chart review of all patients diagnosed with progressive postnatal pansynostosis at a major craniofacial center between 2000 and 2009. Patients with kleebattschädel were excluded. RESULTS: Nineteen patients fit our inclusion criteria. Fifteen patients had a syndromic diagnosis: Crouzon syndrome (n = 8), Saethre-Chotzen syndrome (n = 5), and Pfeiffer syndrome (n = 2). With the exception of one patient with moderate turricephaly, all patients had a relatively normal head shape with cranial indices ranging from 0.72 to 0.93 (mean, 0.81). Patients were diagnosed at an average of 32.4 months; craniosynostosis was suspected based on declining percentile head circumference (n = 14), detection of an apical prominence (n = 12), papilledema (n = 7), and worsening exorbitism (n = 3). Nearly all patients had evidence of increased intracranial pressure. CONCLUSION: Progressive postnatal pansynostosis is insidious; diagnosis is typically delayed because the clinical signs are subtle and appear gradually. All infants or children with known or suspected craniosynostotic disorder and a normal head shape should be carefully monitored; computed tomography is indicated if there is any decrease in percentile head circumference or symptoms of intracranial pressure.

Chromosome microarray testing for patients with congenital heart defects reveals novel disease causing loci and high diagnostic yield.

BACKGROUND: Congenital heart defects (CHD), as the most common congenital anomaly, have been reported to be frequently associated with pathogenic copy number variants (CNVs). Currently, patients with CHD are routinely offered chromosomal microarray (CMA) testing, but the diagnostic yield of CMA on CHD patients has not been extensively evaluated based on a large patient cohort. In this study, we retrospectively assessed the detected CNVs in a total of 514 CHD cases (a 422-case clinical cohort from Boston Children's Hospital (BCH) and a 92-case research cohort from Shanghai Children's Medical Center (SCMC)) and conducted a genotype-phenotype analysis. Furthermore, genes encompassed in pathogenic/likely pathogenic CNVs were prioritized by integrating several tools and public data sources for novel CHD candidate gene identification. RESULTS: Based on the BCH cohort, the overall diagnostic yield of CMA testing for CHD patients was 12.8(pathogenic CNVs)-18.5% (pathogenic and likely pathogenic CNVs). The diagnostic yield of CMA for syndromic CHD was 14.1-20.6% (excluding aneuploidy cases), whereas the diagnostic yield for isolated CHD was 4.3-9.3%. Four recurrent genomic loci (4q terminal region, 15q11.2, 16p12.2 and Yp11.2) were more significantly enriched in cases than in controls. These regions are considered as novel CHD loci. We further identified 20 genes as the most likely novel CHD candidate genes through gene prioritization analysis. CONCLUSION: The high clinical diagnostic yield of CMA in this study provides supportive evidence for CMA as the first-line genetic diagnostic tool for CHD patients. The CNVs detected in our study suggest a number of CHD candidate genes that warrant further investigation.

Whole exome sequencing reveals a novel mutation in CUL7 in a patient with an undiagnosed growth disorder.

We present the case of a 19-year-old man with a growth disorder, which was undefined, despite extensive evaluation. Whole exome sequencing demonstrated a novel homozygous frameshift mutation in CUL7, one of the causative genes of 3-M syndrome. We discuss the utility of exome sequencing in diagnosing rare disorders.