The clinical and molecular spectrum of the KDM6B-related neurodevelopmental disorder.

De novo variants are a leading cause of neurodevelopmental disorders (NDDs), but because every monogenic NDD is different and usually extremely rare, it remains a major challenge to understand the complete phenotype and genotype spectrum of any morbid gene. According to OMIM, heterozygous variants in KDM6B cause "neurodevelopmental disorder with coarse facies and mild distal skeletal abnormalities." Here, by examining the molecular and clinical spectrum of 85 reported individuals with mostly de novo (likely) pathogenic KDM6B variants, we demonstrate that this description is inaccurate and potentially misleading. Cognitive deficits are seen consistently in all individuals, but the overall phenotype is highly variable. Notably, coarse facies and distal skeletal anomalies, as defined by OMIM, are rare in this expanded cohort while other features are unexpectedly common (e.g., hypotonia, psychosis, etc.). Using 3D protein structure analysis and an innovative dual Drosophila gain-of-function assay, we demonstrated a disruptive effect of 11 missense/in-frame indels located in or near the enzymatic JmJC or Zn-containing domain of KDM6B. Consistent with the role of KDM6B in human cognition, we demonstrated a role for the Drosophila KDM6B ortholog in memory and behavior. Taken together, we accurately define the broad clinical spectrum of the KDM6B-related NDD, introduce an innovative functional testing paradigm for the assessment of KDM6B variants, and demonstrate a conserved role for KDM6B in cognition and behavior. Our study demonstrates the critical importance of international collaboration, sharing of clinical data, and rigorous functional analysis of genetic variants to ensure correct disease diagnosis for rare disorders.

Genomic analyses in Cornelia de Lange Syndrome and related diagnoses: Novel candidate genes, genotype-phenotype correlations and common mechanisms.

Cornelia de Lange Syndrome (CdLS) is a rare, dominantly inherited multisystem developmental disorder characterized by highly variable manifestations of growth and developmental delays, upper limb involvement, hypertrichosis, cardiac, gastrointestinal, craniofacial, and other systemic features. Pathogenic variants in genes encoding cohesin complex structural subunits and regulatory proteins (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major pathogenic contributors to CdLS. Heterozygous or hemizygous variants in the genes encoding these five proteins have been found to be contributory to CdLS, with variants in NIPBL accounting for the majority (>60%) of cases, and the only gene identified to date that results in the severe or classic form of CdLS when mutated. Pathogenic variants in cohesin genes other than NIPBL tend to result in a less severe phenotype. Causative variants in additional genes, such as ANKRD11, EP300, AFF4, TAF1, and BRD4, can cause a CdLS-like phenotype. The common role that these genes, and others, play as critical regulators of developmental transcriptional control has led to the conditions they cause being referred to as disorders of transcriptional regulation (or "DTRs"). Here, we report the results of a comprehensive molecular analysis in a cohort of 716 probands with typical and atypical CdLS in order to delineate the genetic contribution of causative variants in cohesin complex genes as well as novel candidate genes, genotype-phenotype correlations, and the utility of genome sequencing in understanding the mutational landscape in this population.

Characteristic physical traits of first-grade children in the United States with fetal alcohol spectrum disorders (FASD) and associated alcohol and drug exposures.

We compared growth, physical features, and minor anomalies in 131 first-grade children with fetal alcohol spectrum disorders (FASD) to those of a representative comparison group of typically developing children from the same populations (n = 1212). The data were collected from three regional sites in the NIAAA-funded Collaboration on FASD Prevalence (CoFASP). Dysmorphology examinations were performed by a team of expert clinical geneticists, and FASD diagnoses were assigned according to the Revised Institute of Medicine Guidelines, which include assessments of growth, dysmorphology, neurobehavior, and maternal risk interviews. We present detailed data on 32 physical traits, minor anomalies, and a summary dysmorphology score for children within each of the four diagnostic categories in the continuum of FASD. There were few differences in the frequency of FASD diagnoses by race or Hispanic ethnicity. Children with FASD were born to mothers who reported using alcohol, tobacco (28.3%), and other drugs (14.2%) during pregnancy. Controlling for tobacco and other drug use, risk analysis indicated that women with a drinking pattern of 3 drinks per drinking day prior to pregnancy were 10 times more likely (p < 0.001, OR = 9.92, 95% CI: 4.6-21.5) to bear a child with FASD than those who reported abstinence prior to pregnancy.

The prevalence of fetal alcohol spectrum disorders in rural communities in South Africa: A third regional sample of child characteristics and maternal risk factors.

BACKGROUND: This study is the ninth cross-sectional community study of fetal alcohol spectrum disorders (FASD) conducted by the multidisciplinary Fetal Alcohol Syndrome Epidemiology Research team in the Western Cape Province of South Africa. It is the third comprehensive study of FASD in a rural, agricultural region of South Africa. METHODS: Population-based, active case ascertainment methods were employed among a school-based cohort to assess child physical and neurobehavioral traits, and maternal risk factor interviews were conducted to identify all children with FASD to determine its prevalence. RESULTS: Consent was obtained for 76.7% of 1158 children attending first grade in the region's public schools. Case-control results are presented for 95 with fetal alcohol syndrome (FAS), 64 with partial fetal alcohol syndrome (PFAS), 77 with alcohol-related neurodevelopmental disorder (ARND), 2 with alcohol-related birth defects (ARBD), and 213 randomly-selected controls. Four techniques estimating FASD prevalence from in-person examinations and testing yielded a range of total FASD prevalence of 206-366 per 1000. The final weighted, estimated prevalence of FAS was 104.5 per 1000, PFAS was 77.7 per 1000, ARND was 125.2 per 1000, and total FASD prevalence was 310 per 1000 (95% CI = 283.4-336.7). Expressed as a percentage, 31% had FASD. Although the rate of total FASD remained steady over 9 years, the proportion of children within the FASD group has changed significantly: FAS trended down and ARND trended up. A detailed evaluation is presented of the specific child physical and neurobehavioral traits integral to assessing the full continuum of FASD. The diagnosis of a child with FASD was significantly associated with maternal proximal risk factors such as: co-morbid prenatal use of alcohol and tobacco (OR = 19.1); maternal drinking of two (OR = 5.9), three (OR = 5.9), four (OR = 38.3), or more alcoholic drinks per drinking day; and drinking in the first trimester (OR = 8.4), first and second trimesters (OR = 17.7), or throughout pregnancy (OR = 18.6). Distal maternal risk factors included the following: slight or small physical status (height, weight, and head circumference), lower BMI, less formal education, late recognition of pregnancy, and higher gravidity, parity, and older age during the index pregnancy. CONCLUSION: The prevalence of FASD remained a significant problem in this region, but the severity of physical traits and anomalies within the continuum of FASD is trending downwards.

Evaluating a general pediatric/adult genetic counseling clinic in a Midwest medical center.

In 2018, the Munroe-Meyer Institute for Genetics & Rehabilitation (MMI) at the University of Nebraska Medical Center (UNMC) in Omaha, NE created a genetic counseling clinic (GCC) to increase access to genetics services and decrease the time spent between a referral and being seen in a general genetics outpatient clinic. In the GCC, genetic counselors led patient encounters and geneticists served as advisors, rather than primary providers. We conducted a chart review of 109 patients seen in the GCC from November 1, 2018, to March 16, 2020, and obtained information regarding patient demographics, indications, and clinical recommendations as a result of the visit. Most patients seen in this clinic were female (65.1%) and aged 19 years of age or older (54.1%). The primary indications for patients in this clinic included review genetic test results (42.2%), coordination of genetic testing for a known familial variant (30.2%), and concerns for personal or family history suspicious of a genetic condition without dysmorphic features (24.8%). The average patient wait time between referral date and appointment date in the GCC was 49.8 days. The two most common clinical recommendations made by genetic counselors in the GCC were genetic testing (56.1%) and/or follow-up with specialist (26.5%). These specialists primarily included endocrinology (n = 5), neurology (n = 4), cardiology (n = 4), ophthalmology (n = 3), and audiology (n = 3). We found that the GCC model may be appropriate for patients with (1) genetic test results requiring interpretation, (2) a known familial variant or (3) genetic testing recommended by a specialist physician. Descriptions of the indications and recommendations for patients seen in this GCC provide a framework for potential implementation of a GCC in other regions across the nation.

Clinical and functional characterization of recurrent missense variants implicated in THOC6-related intellectual disability.

THOC6 encodes a subunit of the THO complex that is part of a highly conserved transcription and export complex known to have roles in mRNA processing and export. Few homozygous or compound heterozygous variants have been identified in the THOC6 gene in patients with a syndromic form of intellectual disability [Beaulieu-Boycott-Innes syndrome (BBIS); MIM: 613680]. Here we report two additional individuals affected with BBIS originating from the north of Europe and sharing a haplotype composed of three very rare missense changes in the THOC6 gene-Trp100Arg, Val234Leu, Gly275Asp. The first individual is a boy who is homozygous for the three-variant haplotype due to a maternal uniparental disomy event. The second is a girl who is compound heterozygous for this haplotype and a previously reported Gly190Glu missense variant. We analyzed the impact of these different amino acid changes on THOC6 protein expression, cellular localization and interaction with the other THO complex subunits. We show that the different THOC6 variants alter the physiological nuclear localizationof the protein and its interaction with at least two THO subunits, THOC1 and THOC5. Two amino acid changes from the three-variant haplotype alone have specific effects and might contribute to the pathogenicity of the haplotype. Overall, we expanded the cohort of currently known individuals with BBIS by reporting two individuals carrying the same recurrent European haplotype composed of three amino acid changes, affecting THOC6 localization and interaction with THO protein partners.

TUBB3 Arg262His causes a recognizable syndrome including CFEOM3, facial palsy, joint contractures, and early-onset peripheral neuropathy.

Microtubules are formed from heterodimers of alpha- and beta-tubulin, each of which has multiple isoforms encoded by separate genes. Pathogenic missense variants in multiple different tubulin isoforms cause brain malformations. Missense mutations in TUBB3, which encodes the neuron-specific beta-tubulin isotype, can cause congenital fibrosis of the extraocular muscles type 3 (CFEOM3) and/or malformations of cortical development, with distinct genotype-phenotype correlations. Here, we report fourteen individuals from thirteen unrelated families, each of whom harbors the identical NM_006086.4 (TUBB3):c.785G>A (p.Arg262His) variant resulting in a phenotype we refer to as the TUBB3 R262H syndrome. The affected individuals present at birth with ptosis, ophthalmoplegia, exotropia, facial weakness, facial dysmorphisms, and, in most cases, distal congenital joint contractures, and subsequently develop intellectual disabilities, gait disorders with proximal joint contractures, Kallmann syndrome (hypogonadotropic hypogonadism and anosmia), and a progressive peripheral neuropathy during the first decade of life. Subsets may also have vocal cord paralysis, auditory dysfunction, cyclic vomiting, and/or tachycardia at rest. All fourteen subjects share a recognizable set of brain malformations, including hypoplasia of the corpus callosum and anterior commissure, basal ganglia malformations, absent olfactory bulbs and sulci, and subtle cerebellar malformations. While similar, individuals with the TUBB3 R262H syndrome can be distinguished from individuals with the TUBB3 E410K syndrome by the presence of congenital and acquired joint contractures, an earlier onset peripheral neuropathy, impaired gait, and basal ganglia malformations.

Expanding the genotypic and phenotypic spectrum in a diverse cohort of 104 individuals with Wiedemann-Steiner syndrome.

Wiedemann-Steiner syndrome (WSS) is an autosomal dominant disorder caused by monoallelic variants in KMT2A and characterized by intellectual disability and hypertrichosis. We performed a retrospective, multicenter, observational study of 104 individuals with WSS from five continents to characterize the clinical and molecular spectrum of WSS in diverse populations, to identify physical features that may be more prevalent in White versus Black Indigenous People of Color individuals, to delineate genotype-phenotype correlations, to define developmental milestones, to describe the syndrome through adulthood, and to examine clinicians' differential diagnoses. Sixty-nine of the 82 variants (84%) observed in the study were not previously reported in the literature. Common clinical features identified in the cohort included: developmental delay or intellectual disability (97%), constipation (63.8%), failure to thrive (67.7%), feeding difficulties (66.3%), hypertrichosis cubiti (57%), short stature (57.8%), and vertebral anomalies (46.9%). The median ages at walking and first words were 20 months and 18 months, respectively. Hypotonia was associated with loss of function (LoF) variants, and seizures were associated with non-LoF variants. This study identifies genotype-phenotype correlations as well as race-facial feature associations in an ethnically diverse cohort, and accurately defines developmental trajectories, medical comorbidities, and long-term outcomes in individuals with WSS.

Fetal alcohol spectrum disorders: current state of diagnosis and treatment.

PURPOSE OF REVIEW: The purpose of this review is to describe recent findings on the clinical presentation, pathogenesis, and management of fetal alcohol spectrum disorders (FASDs). Alcohol causes a range of physical, developmental, and cognitive impairments on the developing fetus. Individuals exposed to alcohol prenatally have a wide variability in dysmorphic and neurologic features. Hence, a greater understanding of the mechanisms through which alcohol induces defects in the developing fetus is imperative in developing therapies that prevent alcohol-induced effects. RECENT FINDINGS: Current research has focused on leveraging technology to developing tools that can aid in the diagnostic process, defining patterns of neurocognition and neuroimaging specific to FASD, developing neurobehavioral and pharmacologic interventions, and expanding access to care. SUMMARY: FASDs are a common cause of neurodevelopmental impairment in school-age children, and their recognition is essential to provide early interventions in order to optimize the outcome for these individuals when they reach adulthood. Although previously thought to be the result of irreversible neurologic injury from prenatal alcohol exposure, recent evidence points to the benefits of applying principles regarding neuroplasticity in improving the lives for patients and their families.

Novel variants in CDH2 are associated with a new syndrome including Peters anomaly.

Peters anomaly (PA) is a congenital corneal opacity associated with corneo-lenticular attachments. PA can be isolated or part of a syndrome with most cases remaining genetically unsolved. Exome sequencing of a trio with syndromic PA and 145 additional unexplained probands with developmental ocular conditions identified a de novo splicing and three novel missense heterozygous CDH2 variants affecting the extracellular cadherin domains in four individuals with PA. Syndromic anomalies were seen in three individuals and included left-sided cardiac lesions, dysmorphic facial features, and decreasing height percentiles; brain magnetic resonance imaging identified agenesis of the corpus callosum and hypoplasia of the inferior cerebellar vermis. CDH2 encodes for N-cadherin, a transmembrane protein that mediates cell-cell adhesion in multiple tissues. Immunostaining in mouse embryonic eyes confirmed N-cadherin is present in the lens stalk at the time of separation from the future cornea and in the developing lens and corneal endothelium at later stages, supporting a possible role in PA. Previous studies in animal models have noted the importance of Cdh2/cdh2 in the development of the eye, heart, brain, and skeletal structures, also consistent with the patient features presented here. Examination of CDH2 in additional patients with PA is indicated to confirm this association.

Differentiating molecular etiologies of Angelman syndrome through facial phenotyping using deep learning.

Angelman syndrome (AS) is caused by several genetic mechanisms that impair the expression of maternally-inherited UBE3A through deletions, paternal uniparental disomy (UPD), UBE3A pathogenic variants, or imprinting defects. Current methods of differentiating the etiology require molecular testing, which is sometimes difficult to obtain. Recently, computer-based facial analysis systems have been used to assist in identifying genetic conditions based on facial phenotypes. We sought to understand if the facial-recognition system DeepGestalt could find differences in phenotype between molecular subtypes of AS. Images and molecular data on 261 individuals with AS ranging from 10 months through 32 years were analyzed by DeepGestalt in a cross-validation model with receiver operating characteristic (ROC) curves generated. The area under the curve (AUC) of the ROC for each molecular subtype was compared and ranked from least to greatest differentiable phenotype. We determined that DeepGestalt demonstrated a high degree of discrimination between the deletion subtype and UPD or imprinting defects, and a lower degree of discrimination with the UBE3A pathogenic variants subtype. Our findings suggest that DeepGestalt can recognize subclinical differences in phenotype based on etiology and may provide decision support for testing.

Ocular measurements in fetal alcohol spectrum disorders.

Fetal alcohol spectrum disorders (FASD) describe a range of physical, behavioral, and neurologic deficits in individuals exposed to alcohol prenatally. Reduced palpebral fissure length is one of the cardinal facial features of FASD. However, other ocular measurements have not been studied extensively in FASD. Using the Fetal Alcohol Syndrome Epidemiologic Research (FASER) database, we investigated how inner canthal distance (ICD), interpupillary distance (IPD), and outer canthal distance (OCD) centiles differed between FASD and non-FASD individuals. We compared ocular measurement centiles in children with FASD to non-FASD individuals and observed reductions in all three centiles for ICD, IPD, and OCD. However, when our non-FASD children who had various forms of growth deficiency (microcephaly, short-stature, or underweight) were compared to controls, we did not observe a similar reduction in ocular measurements. This suggests that reductions in ocular measurements are a direct effect of alcohol on ocular development independent of its effect on growth parameters, which is consistent with animal models showing a negative effect of alcohol on developing neural crest cells. Interpupillary distance centile appeared to be the most significantly reduced ocular measure we evaluated, suggesting it may be a useful measure to be considered in the diagnosis of FASD.

Rubinstein-Taybi syndrome in diverse populations.

Rubinstein-Taybi syndrome (RSTS) is an autosomal dominant disorder, caused by loss-of-function variants in CREBBP or EP300. Affected individuals present with distinctive craniofacial features, broad thumbs and/or halluces, and intellectual disability. RSTS phenotype has been well characterized in individuals of European descent but not in other populations. In this study, individuals from diverse populations with RSTS were assessed by clinical examination and facial analysis technology. Clinical data of 38 individuals from 14 different countries were analyzed. The median age was 7 years (age range: 7 months to 47 years), and 63% were females. The most common phenotypic features in all population groups included broad thumbs and/or halluces in 97%, convex nasal ridge in 94%, and arched eyebrows in 92%. Face images of 87 individuals with RSTS (age range: 2 months to 47 years) were collected for evaluation using facial analysis technology. We compared images from 82 individuals with RSTS against 82 age- and sex-matched controls and obtained an area under the receiver operating characteristic curve (AUC) of 0.99 (p < .001), demonstrating excellent discrimination efficacy. The discrimination was, however, poor in the African group (AUC: 0.79; p = .145). Individuals with EP300 variants were more effectively discriminated (AUC: 0.95) compared with those with CREBBP variants (AUC: 0.93). This study shows that clinical examination combined with facial analysis technology may enable earlier and improved diagnosis of RSTS in diverse populations.

Fetal Alcohol Spectrum Disorders in a Southeastern County of the United States: Child Characteristics and Maternal Risk Traits.

OBJECTIVE: To detail the characteristic traits of children with fetal alcohol spectrum disorders (FASDs) and maternal risk factors in a southeastern U.S. County. METHODS: Independent samples were drawn from 2 different cohorts of first-grade students. All consented children (49.8%) were measured for height, weight, and head circumference, and those ≤ 25th centile entered the study along with a random sample drawn from all enrolled students. Study children were examined for physical growth, dysmorphology, and neurobehavior, and their mothers were interviewed. RESULTS: Total dysmorphology scores discriminated well the physical traits of children across the FASD continuum: fetal alcohol syndrome (FAS) = 15.8, partial FAS (PFAS) = 10.8, alcohol-related neurobehavioral disorder (ARND) = 5.2, and typically developing controls = 4.4. Additionally, a neurobehavioral battery distinguished children with each FASD diagnosis from controls. Behavioral problems qualified more children for FASD diagnoses than cognitive traits. Significant proximal maternal risk variables were as follows: reports of prepregnancy drinking, drinking in any trimester, and comorbid use of other drugs in lifetime and during pregnancy, especially alcohol and marijuana (14.9% among mothers of children with FASD vs. 0.4% for controls). Distal maternal risks included reports of other health problems (e.g., depression), living unmarried with a partner during pregnancy, and a lower level of spirituality. Controlling for other drug use during pregnancy, having a child diagnosed with a FASD was 17.5 times greater for women who reported usual consumption of 3 drinks per drinking day prior to pregnancy than for nondrinking mothers (p < 0.001, 95% CI = 5.1 to 59.9). There was no significant difference in the prevalence of FASD by race, Hispanic ethnicity, or socioeconomic status. The prevalence of FASD was not lower than 17.3 per 1,000, and weighted estimated prevalence was 49.0 per 1,000 or 4.9%. CONCLUSION: This site had the second lowest rate in the CoFASP study, yet children with FASD are prevalent.

Fetal Alcohol Spectrum Disorders in a Midwestern City: Child Characteristics, Maternal Risk Traits, and Prevalence.

OBJECTIVE: To determine the characteristics of children with fetal alcohol spectrum disorders (FASD) and their mothers in a Midwestern city. METHODS: Case-control samples were drawn from 2 separate first-grade cohorts (combined N = 4,047) in every city school using different methods. In Cohort Sample 1, all consented small children (≤25th centile on height, weight, and/or head circumference) entered the study along with a random sample from all enrolled students. Cohort Sample 2 was drawn totally at random. Child growth, dysmorphology, and neurobehavior were assessed using the Collaboration on FASD Prevalence (CoFASP) criteria, and mothers were interviewed. RESULTS: For the samples combined, 891 children received dysmorphology examinations, and 692 were case-conferenced for final diagnosis. Forty-four children met criteria for FASD. Total dysmorphology scores differentiated diagnostic groups: fetal alcohol syndrome (FAS), 16.7; partial FAS, 11.8; alcohol-related neurodevelopmental disorder (ARND), 6.1; and typically developing controls, 4.2. Neurobehavioral tests distinguished children with FASD from controls, more for behavioral problems than cognitive delay. Children with ARND demonstrated the poorest neurobehavioral indicators. An adjusted regression model of usual prepregnancy drinking indicated that maternal reports of 3 drinks per drinking day (DDD) were significantly associated with a FASD diagnosis (p = 0.020, OR = 10.1, 95% CI = 1.44 to 70.54), as were 5 or more DDD (p < 0.001, OR = 26.47, 95% CI = 4.65 to 150.62). Other significant maternal risk factors included the following: self-reported drinking in any trimester; smoking and cocaine use during pregnancy; later pregnancy recognition and later and less prenatal care; lower maternal weight, body mass index (BMI), and head circumference; and unmarried status. There was no significant difference in FASD prevalence by race, Hispanic ethnicity, or socioeconomic status at this site, where the prevalence of FASD was 14.4 to 41.2 per 1,000 (1.4 to 4.1%). CONCLUSION: This city displayed the lowest prevalence of FASD of the 4 CoFASP sites. Nevertheless, FASD were common, and affected children demonstrated a common, recognizable, and measurable array of traits.

Fetal Alcohol Spectrum Disorders in a Rocky Mountain Region City: Child Characteristics, Maternal Risk Traits, and Prevalence.

OBJECTIVE: To document prevalence and traits of children with fetal alcohol spectrum disorders (FASD) and maternal risk factors in a Rocky Mountain city. METHODS: Variations on active case ascertainment methods were used in 2 first-grade cohorts in all city schools. The consent rate was 59.2%. Children were assessed for physical growth, dysmorphology, and neurobehavior and their mothers interviewed. RESULTS: Thirty-eight children were diagnosed with FASD and compared with 278 typically developing controls. Total dysmorphology scores summarized well the key physical indicators of FASD and defined specific diagnostic groups. On average, children with FASD performed significantly poorer than controls on intellectual, adaptive, learning, attention, and behavioral tasks. More mothers of children with FASD reported drinking prior to pregnancy and in the first and second trimesters, and had partners with drinking problems than mothers of controls; however, reports of comorbid alcohol use and 6 other drugs were similar for mothers of children with FASD and mothers of controls. Mothers of children with FASD were significantly younger at pregnancy, had lower average weight before pregnancy and less education, initiated prenatal clinic visits later, and reported more health problems (e.g., stomach ulcers and accidents). Children with FASD had significantly lower birth weight and more problems at birth, and were less likely to be living with biological mother and father. Controlling for other drug and tobacco use, a FASD diagnosis is 6.7 times (OR = 6.720, 95% CI = 1.6 to 28.0) more likely among children of women reporting prepregnancy drinking of 3 drinks per drinking day (DDD) and 7.6 times (OR = 7.590, 95% CI = 2.0 to 31.5) more likely at 5 DDD. Prevalence of FAS was 2.9-5.8 per 1,000 children, and total FASD was 34.9 to 82.5 per 1,000 children or 3.5 to 8.3% at this site. CONCLUSION: This site had the second highest prevalence of FASD of the 4 Collaboration on FASD Prevalence sites and clearly identifiable child and maternal risk traits.

Deleterious de novo variants of X-linked ZC4H2 in females cause a variable phenotype with neurogenic arthrogryposis multiplex congenita.

Pathogenic variants in the X-linked gene ZC4H2, which encodes a zinc-finger protein, cause an infrequently described syndromic form of arthrogryposis multiplex congenita (AMC) with central and peripheral nervous system involvement. We present genetic and detailed phenotypic information on 23 newly identified families and simplex cases that include 19 affected females from 18 families and 14 affected males from nine families. Of note, the 15 females with deleterious de novo ZC4H2 variants presented with phenotypes ranging from mild to severe, and their clinical features overlapped with those seen in affected males. By contrast, of the nine carrier females with inherited ZC4H2 missense variants that were deleterious in affected male relatives, four were symptomatic. We also compared clinical phenotypes with previously published cases of both sexes and provide an overview on 48 males and 57 females from 42 families. The spectrum of ZC4H2 defects comprises novel and recurrent mostly inherited missense variants in affected males, and de novo splicing, frameshift, nonsense, and partial ZC4H2 deletions in affected females. Pathogenicity of two newly identified missense variants was further supported by studies in zebrafish. We propose ZC4H2 as a good candidate for early genetic testing of males and females with a clinical suspicion of fetal hypo-/akinesia and/or (neurogenic) AMC.

An immune tolerance approach using transient low-dose methotrexate in the ERT-naïve setting of patients treated with a therapeutic protein: experience in infantile-onset Pompe disease.

PURPOSE: To investigate immune tolerance induction with transient low-dose methotrexate (TLD-MTX) initiated with recombinant human acid α-glucosidase (rhGAA), in treatment-naïve cross-reactive immunologic material (CRIM)-positive infantile-onset Pompe disease (IOPD) patients. METHODS: Newly diagnosed IOPD patients received subcutaneous or oral 0.4 mg/kg TLD-MTX for 3 cycles (3 doses/cycle) with the first 3 rhGAA infusions. Anti-rhGAA IgG titers, classified as high-sustained (HSAT; ≥51,200, ≥2 times after 6 months), sustained intermediate (SIT; ≥12,800 and <51,200 within 12 months), or low (LT; ≤6400 within 12 months), were compared with those of 37 CRIM-positive IOPD historic comparators receiving rhGAA alone. RESULTS: Fourteen IOPD TLD-MTX recipients at the median age of 3.8 months (range, 0.7-13.5 months) had a median last titer of 150 (range, 0-51,200) at median rhGAA duration ~83 weeks (range, 36-122 weeks). One IOPD patient (7.1%) developed titers in the SIT range and one patient (7.1%) developed titers in the HSAT range. Twelve of the 14 patients (85.7%) that received TLD-MTX remained LT, versus 5/37 HSAT (peak 51,200-409,600), 7/37 SIT (12,800-51,000), and 23/37 LT (200-12,800) among comparators. CONCLUSION: Results of TLD-MTX coinitiated with rhGAA are encouraging and merit a larger longitudinal study.

Choline transporter mutations in severe congenital myasthenic syndrome disrupt transporter localization.

The presynaptic, high-affinity choline transporter is a critical determinant of signalling by the neurotransmitter acetylcholine at both central and peripheral cholinergic synapses, including the neuromuscular junction. Here we describe an autosomal recessive presynaptic congenital myasthenic syndrome presenting with a broad clinical phenotype due to homozygous choline transporter missense mutations. The clinical phenotype ranges from the classical presentation of a congenital myasthenic syndrome in one patient (p.Pro210Leu), to severe neurodevelopmental delay with brain atrophy (p.Ser94Arg) and extend the clinical outcomes to a more severe spectrum with infantile lethality (p.Val112Glu). Cells transfected with mutant transporter construct revealed a virtually complete loss of transport activity that was paralleled by a reduction in transporter cell surface expression. Consistent with these findings, studies to determine the impact of gene mutations on the trafficking of the Caenorhabditis elegans choline transporter orthologue revealed deficits in transporter export to axons and nerve terminals. These findings contrast with our previous findings in autosomal dominant distal hereditary motor neuropathy of a dominant-negative frameshift mutation at the C-terminus of choline transporter that was associated with significantly reduced, but not completely abrogated choline transporter function. Together our findings define divergent neuropathological outcomes arising from different classes of choline transporter mutation with distinct disease processes and modes of inheritance. These findings underscore the essential role played by the choline transporter in sustaining acetylcholine neurotransmission at both central and neuromuscular synapses, with important implications for treatment and drug selection.

Prevalence of Fetal Alcohol Spectrum Disorders in 4 US Communities.

Importance: Fetal alcohol spectrum disorders are costly, life-long disabilities. Older data suggested the prevalence of the disorder in the United States was 10 per 1000 children; however, there are few current estimates based on larger, diverse US population samples. Objective: To estimate the prevalence of fetal alcohol spectrum disorders, including fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder, in 4 regions of the United States. Design, Setting, and Participants: Active case ascertainment methods using a cross-sectional design were used to assess children for fetal alcohol spectrum disorders between 2010 and 2016. Children were systematically assessed in the 4 domains that contribute to the fetal alcohol spectrum disorder continuum: dysmorphic features, physical growth, neurobehavioral development, and prenatal alcohol exposure. The settings were 4 communities in the Rocky Mountain, Midwestern, Southeastern, and Pacific Southwestern regions of the United States. First-grade children and their parents or guardians were enrolled. Exposures: Alcohol consumption during pregnancy. Main Outcomes and Measures: Prevalence of fetal alcohol spectrum disorders in the 4 communities was the main outcome. Conservative estimates for the prevalence of the disorder and 95% CIs were calculated using the eligible first-grade population as the denominator. Weighted prevalences and 95% CIs were also estimated, accounting for the sampling schemes and using data restricted to children who received a full evaluation. Results: A total of 6639 children were selected for participation from a population of 13 146 first-graders (boys, 51.9%; mean age, 6.7 years [SD, 0.41] and white maternal race, 79.3%). A total of 222 cases of fetal alcohol spectrum disorders were identified. The conservative prevalence estimates for fetal alcohol spectrum disorders ranged from 11.3 (95% CI, 7.8-15.8) to 50.0 (95% CI, 39.9-61.7) per 1000 children. The weighted prevalence estimates for fetal alcohol spectrum disorders ranged from 31.1 (95% CI, 16.1-54.0) to 98.5 (95% CI, 57.5-139.5) per 1000 children. Conclusions and Relevance: Estimated prevalence of fetal alcohol spectrum disorders among first-graders in 4 US communities ranged from 1.1% to 5.0% using a conservative approach. These findings may represent more accurate US prevalence estimates than previous studies but may not be generalizable to all communities.