Heterozygous MAP3K20 variants cause ectodermal dysplasia, craniosynostosis, sensorineural hearing loss, and limb anomalies.

Biallelic pathogenic variants in MAP3K20, which encodes a mitogen-activated protein kinase, are a rare cause of split-hand foot malformation (SHFM), hearing loss, and nail abnormalities or congenital myopathy. However, heterozygous variants in this gene have not been definitively associated with a phenotype. Here, we describe the phenotypic spectrum associated with heterozygous de novo variants in the linker region between the kinase domain and leucine zipper domain of MAP3K20. We report five individuals with diverse clinical features, including craniosynostosis, limb anomalies, sensorineural hearing loss, and ectodermal dysplasia-like phenotypes who have heterozygous de novo variants in this specific region of the gene. These individuals exhibit both shared and unique clinical manifestations, highlighting the complexity and variability of the disorder. We propose that the involvement of MAP3K20 in endothelial-mesenchymal transition provides a plausible etiology of these features. Together, these findings characterize a disorder that both expands the phenotypic spectrum associated with MAP3K20 and highlights the need for further studies on its role in early human development.

Early-onset severe spinocerebellar ataxia 42 with neurodevelopmental deficits (SCA42ND): Case report, pharmacological trial, and literature review.

Early-onset severe spinocerebellar ataxia 42 with neurodevelopmental deficits (SCA42ND, MIM#604065) is an ultrarare autosomal dominant syndrome related to de novo CACNA1G gain-of-function pathogenic variants. All patients with SCA42ND show cerebellar atrophy and/or hypoplasia on neuroimaging and share common features such as dysmorphic features, global developmental delay, and axial hypotonia, all manifesting within the first year of life. To date, only 10 patients with SCA42ND have been reported with functionally confirmed gain-of-function variants, bearing either of two recurrent pathogenic variants. We describe a girl with congenital ataxia, without epilepsy, and a de novo p.Ala961Thr pathogenic variant in CACNA1G. We review the published subjects with the aim of better characterizing the dysmorphic features that may be crucial for clinical recognition of SCA42ND. Cerebellar atrophy, together with digital anomalies, particularly broad thumbs and/or halluces, should lead to clinical suspicion of this disease. We describe the first pharmacological attempt to treat a patient with SCA42ND using zonisamide, an antiepileptic drug with T-type channel blocker activity, in an off-label indication using an itemized study protocol. No efficacy was observed at the dose tested. However, without pharmacological treatment, she showed a positive evolution in neurodevelopment during the follow-up.

MECP2-Related Disorders in Males.

Methyl CpG binding protein 2 (MECP2) is located at Xq28 and is a multifunctional gene with ubiquitous expression. Loss-of-function mutations in MECP2 are associated with Rett syndrome (RTT), which is a well-characterized disorder that affects mainly females. In boys, however, mutations in MECP2 can generate a wide spectrum of clinical presentations that range from mild intellectual impairment to severe neonatal encephalopathy and premature death. Thus, males can be more difficult to classify and diagnose than classical RTT females. In addition, there are some variants of unknown significance in MECP2, which further complicate the diagnosis of these children. Conversely, the entire duplication of the MECP2 gene is related to MECP2 duplication syndrome (MDS). Unlike in RTT, in MDS, males are predominantly affected. Usually, the duplication is inherited from an apparently asymptomatic carrier mother. Both syndromes share some characteristics, but also differ in some aspects regarding the clinical picture and evolution. In the following review, we present a thorough description of the different types of MECP2 variants and alterations that can be found in males, and explore several genotype-phenotype correlations, although there is still a lot to understand.

CACNA1A Mutations Causing Early Onset Ataxia: Profiling Clinical, Dysmorphic and Structural-Functional Findings.

The CACNA1A gene encodes the pore-forming α1A subunit of the voltage-gated CaV2.1 Ca2+ channel, essential in neurotransmission, especially in Purkinje cells. Mutations in CACNA1A result in great clinical heterogeneity with progressive symptoms, paroxysmal events or both. During infancy, clinical and neuroimaging findings may be unspecific, and no dysmorphic features have been reported. We present the clinical, radiological and evolutionary features of three patients with congenital ataxia, one of them carrying a new variant. We report the structural localization of variants and their expected functional consequences. There was an improvement in cerebellar syndrome over time despite a cerebellar atrophy progression, inconsistent response to acetazolamide and positive response to methylphenidate. The patients shared distinctive facial gestalt: oval face, prominent forehead, hypertelorism, downslanting palpebral fissures and narrow nasal bridge. The two α1A affected residues are fully conserved throughout evolution and among the whole human CaV channel family. They contribute to the channel pore and the voltage sensor segment. According to structural data analysis and available functional characterization, they are expected to exert gain- (F1394L) and loss-of-function (R1664Q/R1669Q) effect, respectively. Among the CACNA1A-related phenotypes, our results suggest that non-progressive congenital ataxia is associated with developmental delay and dysmorphic features, constituting a recognizable syndromic neurodevelopmental disorder.

Molecular characterization of Spanish patients with MECP2 duplication syndrome.

MECP2 duplication syndrome (MDS) is an X-linked neurodevelopmental disorder characterized by a severe to profound intellectual disability, early onset hypotonia and diverse psycho-motor and behavioural features. To date, fewer than 200 cases have been published. We report the clinical and molecular characterization of a Spanish MDS cohort that included 19 boys and 2 girls. Clinical suspicions were confirmed by array comparative genomic hybridization and multiplex ligation-dependent probe amplification (MLPA). Using, a custom in-house MLPA assay, we performed a thorough study of the minimal duplicated region, from which we concluded a complete duplication of both MECP2 and IRAK1 was necessary for a correct MDS diagnosis, as patients with partial MECP2 duplications lacked some typical clinical traits present in other MDS patients. In addition, the duplication location may be related to phenotypic severity. This observation may provide a new approach for genotype-phenotype correlations, and thus more personalized genetic counselling.

AZATAX: Acetazolamide safety and efficacy in cerebellar syndrome in PMM2 congenital disorder of glycosylation (PMM2-CDG).

OBJECTIVE: Phosphomannomutase deficiency (PMM2 congenital disorder of glycosylation [PMM2-CDG]) causes cerebellar syndrome and strokelike episodes (SLEs). SLEs are also described in patients with gain-of-function mutations in the CaV2.1 channel, for which acetazolamide therapy is suggested. Impairment in N-glycosylation of CaV2.1 promotes gain-of-function effects and may participate in cerebellar syndrome in PMM2-CDG. AZATAX was designed to establish whether acetazolamide is safe and improves cerebellar syndrome in PMM2-CDG. METHODS: A clinical trial included PMM2-CDG patients, with a 6-month first-phase single acetazolamide therapy group, followed by a randomized 5-week withdrawal phase. Safety was assessed. The primary outcome measure was improvement in the International Cooperative Ataxia Rating Scale (ICARS). Other measures were the Nijmegen Pediatric CDG Rating Scale (NPCRS), a syllable repetition test (PATA test), and cognitive scores. RESULTS: Twenty-four patients (mean age = 12.3 ± 4.5 years) were included, showing no serious adverse events. Thirteen patients required dose adjustment due to low bicarbonate or asthenia. There were improvements on ICARS (34.9 ± 23.2 vs 40.7 ± 24.8, effect size = 1.48, 95% confidence interval [CI] = 4.0-7.6, p < 0.001), detected at 6 weeks in 18 patients among the 20 responders, on NPCRS (95% CI = 0.3-1.6, p = 0.013) and on the PATA test (95% CI = 0.5-3.0, p = 0.006). Acetazolamide improved prothrombin time, factor X, and antithrombin. Clinical severity, epilepsy, and lipodystrophy predicted greater response. The randomized withdrawal phase showed ICARS worsening in the withdrawal group (effect size = 1.46, 95% CI = 2.65-7.52, p = 0.001). INTERPRETATION: AZATAX is the first clinical trial of PMM2-CDG. Acetazolamide is well tolerated and effective for motor cerebellar syndrome. Its ability to prevent SLEs and its long-term effects on kidney function should be addressed in future studies. Ann Neurol 2019;85:740-751.

Okur-Chung neurodevelopmental syndrome in a patient from Spain.

Okur-Chung neurodevelopmental syndrome (OCNS, MIM#617062) is a rare autosomal dominant syndrome related to CSNK2A1 mutations. It is characterized by intellectual disability, hypotonia, feeding and speech difficulties, dysmorphic features, and multisystem involvement. To date, less than 30 patients with OCNS have been described in detail in the literature, primarily in Asian populations. Here, we report a 5-year-old Spanish female with OCNS arising from a novel CSNK2A1 mutation c.149A>G, p.Tyr50Cys. Although her clinical features were compatible with OCNS syndrome, magnetic resonance imaging unexpectedly showed a duplication of the pituitary gland, a clinical finding not previously related to any known genetic condition. Other novel signs were an absence of the olfactory bulbs and multiple duplications of cervical vertebrae. We suggest that the midline abnormalities may be a significant part of this condition and lead to diagnostic suspicion. However, further descriptions are needed.

Clinical Assessment of Dysarthria in Children with Cerebellar Syndrome Associated with PMM2-CDG.

Phosphomannomutase deficiency (PMM2-CDG) causes a cerebellar syndrome that has been evaluated using the International Cooperative Ataxia Rating Scale (ICARS). However, no particular dysarthria tests have been used. Speech ICARS subscore subjectively assesses fluency and clarity of speech with two items. Repetition of syllables, traditionally used for characterization of ataxic speech, was validated in early-onset ataxia conditions. We assess the validity of the PATA test (SCA Functional Index [SCAFI]) in PMM2-CDG patients.PATA rates from 20 patients were compared with a control population were and correlated with ICARS and neuroimaging.There was a difference between the PATA rate in patients and controls. PATA rate increased with age in controls. In patients, the improvement of PATA rate with age was not significant. In patients, the PATA rate was negatively correlated with the total ICARS score and the Speech ICARS subscore. Regarding neuroimaging, midsaggital vermis relative diameter was positively correlated with PATA results. These last differences were also significant when the results are corrected by age.PATA rate provides an easy measure for a quantitative assessment of dysarthria that may help clinicians to monitor patients' evolution in a regular consultation. It could also be used in PMM2-CDG clinical trials implementing ICARS speech subscore information.

Stroke-Like Episodes and Cerebellar Syndrome in Phosphomannomutase Deficiency (PMM2-CDG): Evidence for Hypoglycosylation-Driven Channelopathy.

Stroke-like episodes (SLE) occur in phosphomannomutase deficiency (PMM2-CDG), and may complicate the course of channelopathies related to Familial Hemiplegic Migraine (FHM) caused by mutations in CACNA1A (encoding CaV2.1 channel). The underlying pathomechanisms are unknown. We analyze clinical variables to detect risk factors for SLE in a series of 43 PMM2-CDG patients. We explore the hypothesis of abnormal CaV2.1 function due to aberrant N-glycosylation as a potential novel pathomechanism of SLE and ataxia in PMM2-CDG by using whole-cell patch-clamp, N-glycosylation blockade and mutagenesis. Nine SLE were identified. Neuroimages showed no signs of stroke. Comparison of characteristics between SLE positive versus negative patients' group showed no differences. Acute and chronic phenotypes of patients with PMM2-CDG or CACNA1A channelopathies show similarities. Hypoglycosylation of both CaV2.1 subunits (α1A and α2α) induced gain-of-function effects on channel gating that mirrored those reported for pathogenic CACNA1A mutations linked to FHM and ataxia. Unoccupied N-glycosylation site N283 at α1A contributes to a gain-of-function by lessening CaV2.1 inactivation. Hypoglycosylation of the α2δ subunit also participates in the gain-of-function effect by promoting voltage-dependent opening of the CaV2.1 channel. CaV2.1 hypoglycosylation may cause ataxia and SLEs in PMM2-CDG patients. Aberrant CaV2.1 N-glycosylation as a novel pathomechanism in PMM2-CDG opens new therapeutic possibilities.

Longitudinal volumetric and 2D assessment of cerebellar atrophy in a large cohort of children with phosphomannomutase deficiency (PMM2-CDG).

OBJECTIVE: We aim to delineate the progression of cerebellar atrophy (the primary neuroimaging finding) in children with phosphomannomutase-deficiency (PMM2-CDG) by analyzing longitudinal MRI studies and performing cerebellar volumetric analysis and a 2D cerebellar measurement. METHODS: Statistical analysis was used to compare MRI measurements [midsagittal vermis relative diameter (MVRD) and volume] of children with PMM2-CDG and sex- and age-matched controls, and to determine the rate of progression of cerebellar atrophy at different ages. RESULTS: Fifty MRI studies of 33 PMM2-CDG patients were used for 2D evaluation, and 19 MRI studies were available for volumetric analysis. Results from a linear regression model showed that patients have a significantly lower MVRD and cerebellar volume compared to controls (p < 0.001 and p < 0.001 respectively). There was a significant negative correlation between age and MVRD for patients (p = 0.014). The rate of cerebellar atrophy measured by the loss of MVRD and cerebellar volume per year was higher at early ages (r = -0.578, p = 0.012 and r = -0.323, p = 0.48 respectively), particularly in patients under 11 years (p = 0.004). There was a significant positive correlation between MVRD and cerebellar volume in PMM2-CDG patients (r = 0.669, p = 0.001). CONCLUSIONS: Our study quantifies a progression of cerebellar atrophy in PMM2-CDG patients, particularly during the first decade of life, and suggests a simple and reliable measure, the MVRD, to monitor cerebellar atrophy. Quantitative measurement of MVRD and cerebellar volume are essential for correlation with phenotype and outcome, natural follow-up, and monitoring in view of potential therapies in children with PMM2-CDG.

Expanding the Phenotypic Spectrum of TRAF7-Related Cardiac, Facial, and Digital Anomalies With Developmental Delay: Report of 11 New Cases and Literature Review.

BACKGROUND: TRAF7-related cardiac, facial, and digital anomalies with developmental delay (CAFDADD), a multisystemic neurodevelopmental disorder caused by germline missense variants in the TRAF7 gene, exhibits heterogeneous clinical presentations. METHODS: We present a detailed description of 11 new TRAF7-related CAFDADD cases, featuring eight distinct variants, including a novel one. RESULTS: Phenotypic analysis and a comprehensive review of the 58 previously reported cases outline consistent clinical presentations, emphasizing dysmorphic features, developmental delay, endocrine manifestations, and cardiac defects. In this enlarged collection, novelties include a wider range of cognitive dysfunction, with some individuals exhibiting normal development despite early psychomotor delay. Communication challenges, particularly in expressive language, are prevalent, necessitating alternative communication methods. Autistic traits, notably rigidity, are observed in the cohort. Also, worth highlighting are hearing loss, sleep disturbances, and endocrine anomalies, including growth deficiency. Cardiac defects, frequently severe, pose early-life complications. Facial features, including arched eyebrows, contribute to the distinct gestalt. A novel missense variant, p.(Arg653Leu), further underscores the complex relationship between germline TRAF7 variants and somatic changes linked to meningiomas. CONCLUSIONS: Our comprehensive analysis expands the phenotypic spectrum, emphasizing the need for oncological evaluations and proposing an evidence-based schedule for clinical management. This study contributes to a better understanding of TRAF7-related CAFDADD, offering insights for improved diagnosis, intervention, and patient care.

Menke-Hennekam syndrome; delineation of domain-specific subtypes with distinct clinical and DNA methylation profiles.

CREB-binding protein (CBP, encoded by CREBBP) and its paralog E1A-associated protein (p300, encoded by EP300) are involved in histone acetylation and transcriptional regulation. Variants that produce a null allele or disrupt the catalytic domain of either protein cause Rubinstein-Taybi syndrome (RSTS), while pathogenic missense and in-frame indel variants in parts of exons 30 and 31 cause phenotypes recently described as Menke-Hennekam syndrome (MKHK). To distinguish MKHK subtypes and define their characteristics, molecular and extended clinical data on 82 individuals (54 unpublished) with variants affecting CBP (n = 71) or p300 (n = 11) (NP_004371.2 residues 1,705-1,875 and NP_001420.2 residues 1,668-1,833, respectively) were summarized. Additionally, genome-wide DNA methylation profiles were assessed in DNA extracted from whole peripheral blood from 54 individuals. Most variants clustered closely around the zinc-binding residues of two zinc-finger domains (ZZ and TAZ2) and within the first α helix of the fourth intrinsically disordered linker (ID4) of CBP/p300. Domain-specific methylation profiles were discerned for the ZZ domain in CBP/p300 (found in nine out of 10 tested individuals) and TAZ2 domain in CBP (in 14 out of 20), while a domain-specific diagnostic episignature was refined for the ID4 domain in CBP/p300 (in 21 out of 21). Phenotypes including intellectual disability of varying degree and distinct physical features were defined for each of the regions. These findings demonstrate existence of at least three MKHK subtypes, which are domain specific (MKHK-ZZ, MKHK-TAZ2, and MKHK-ID4) rather than gene specific (CREBBP/EP300). DNA methylation episignatures enable stratification of molecular pathophysiologic entities within a gene or across a family of paralogous genes.

GestaltMatcher Database - A global reference for the facial phenotypic variability of rare human diseases.

Dysmorphologists sometimes encounter challenges in recognizing disorders due to phenotypic variability influenced by factors such as age and ethnicity. Moreover, the performance of Next Generation Phenotyping Tools such as GestaltMatcher is dependent on the diversity of the training set. Therefore, we developed GestaltMatcher Database (GMDB) - a global reference for the phenotypic variability of rare diseases that complies with the FAIR-principles. We curated dysmorphic patient images and metadata from 2,224 publications, transforming GMDB into an online dynamic case report journal. To encourage clinicians worldwide to contribute, each case can receive a Digital Object Identifier (DOI), making it a citable micro-publication. This resulted in a collection of 2,312 unpublished images, partly with longitudinal data. We have compiled a collection of 10,189 frontal images from 7,695 patients representing 683 disorders. The web interface enables gene- and phenotype-centered queries for registered users (https://db.gestaltmatcher.org/). Despite the predominant European ancestry of most patients (59%), our global collaborations have facilitated the inclusion of data from frequently underrepresented ethnicities, with 17% Asian, 4% African, and 6% with other ethnic backgrounds. The analysis has revealed a significant enhancement in GestaltMatcher performance across all ethnic groups, incorporating non-European ethnicities, showcasing a remarkable increase in Top-1-Accuracy by 31.56% and Top-5-Accuracy by 12.64%. Importantly, this improvement was achieved without altering the performance metrics for European patients. GMDB addresses dysmorphology challenges by representing phenotypic variability and including underrepresented groups, enhancing global diagnostic rates and serving as a vital clinician reference database.

Targeting the Gut Microbiome in Prader-Willi Syndrome.

Overwhelming evidence demonstrates an important role of the gut microbiome in the development of a wide range of diseases, including obesity, metabolic disorders, and mental health symptoms. Indeed, interventions targeting the gut microbiome are being actively investigated as a therapeutic strategy to tackle these diseases. Given that obesity and mental health symptoms are both hallmarks of Prader-Willi syndrome, targeting the gut microbiome may be a promising therapeutical strategy. Only a few studies have investigated the gut microbiome in the context of Prader-Willi syndrome and assessed the efficacy of probiotic supplementation as a therapeutic strategy for this disease. Here, we review the knowledge obtained to this date regarding the gut microbiome in individuals with Prader-Willi syndrome. The limited evidence available indicate that probiotic supplementation improves some metabolic and mental health aspects, however further studies are warranted to determine whether targeting the gut microbiome may constitute a safe and efficient strategy to treat individuals with Prader-Willi syndrome.

Platelet Dysfunction in Noonan and 22q11.2 Deletion Syndromes in Childhood.

INTRODUCTION: An underlying thrombocytopathy seems to be responsible for hemorrhagic symptoms in patients diagnosed with 22q11.2 deletion syndrome (22q11DS) or Noonan syndrome (NS). In 22q11DS, it is explained by a defect in the membrane glycoprotein (GP) complex Ib-V-IX. The cause of thrombocytopathy in NS remains unclear. AIM: The objective is to study the incidence of thrombocytopathy in pediatric patients diagnosed with 22q11DS or NS assessing the utility of ISTH-BAT questionnaire and laboratory techniques. MATERIALS AND METHODS: Prospective study between March and December 2018 in children (2-18 years old) diagnosed with 22q11DS or NS. Hemorrhagic symptoms using ISTH-BAT score, total cell blood count, platelet indices, PFA-200 closure times, and platelet aggregation were evaluated in all patients and membrane GP expression in 22q11DS patients. RESULTS: Nearly 70% of NS patients (n = 22) had a platelet aggregation defect without thrombocytopenia. A defect of platelet aggregation with adenosine diphosphate (ADP) and epinephrine was the most frequent pattern. A statistically significant inverse correlation between closure times and aggregation with arachidonic acid (p = 0.049, p = 0.043) and epinephrine (p = 0.021, p = 0.035), and ADP (p = 0.117, p = 0.05) was found. Total 5 out of 29 patients diagnosed with 22q11DS had macrothrombocytopenia; more noteworthy in older patients. Twenty-six patients showed an impairment in ristocetin-induced platelet aggregation that correlated with prolonged collagen/epinephrine (p = 0.034) and collagen/ADP (p = 0.01). A significant association between ISTH-BAT score >3 and closure times (p = 0.022, p = 0.002) and aggregation defect with ristocetin (p = 0.043) was also demonstrated. CONCLUSION: Most NS and 22q11DS patients show an impairment of platelet aggregation that correlates with closure times. In 22q11DS patients, these results were also related to hemorrhagic symptoms.

A quantitative assessment of the evolution of cerebellar syndrome in children with phosphomannomutase-deficiency (PMM2-CDG).

BACKGROUND: We aim to delineate the progression of cerebellar syndrome in children with phosphomannomutase-deficiency (PMM2-CDG) using the International Cooperative Ataxia Rating Scale (ICARS). We sought correlation between cerebellar volumetry and clinical situation. We prospectively evaluated PMM2-CDG patients aged from 5 to 18 years through ICARS at two different time points set apart by at least 20 months. We reviewed available MRIs and performed volumetric analysis when it was possible. RESULTS: From the eligible 24, four patients were excluded due to severe mental disability (n = 2) and supratentorial lesions (n = 2). Two different ICARS evaluations separated by more than 20 months were available for 14 patients showing an improvement in the cerebellar syndrome: ICARS1: 35.71 versus ICARS2: 30.07 (p < 0.001). When we considered time, we saw an improvement of 2.64 points in the ICARS per year with an SD of 1.97 points (p < 0.001). The ICARS subscales results improved with time, reaching statistical significance in "Posture and gait" (p < 0.001), "Kinetic functions" (p = 0.04) and "Speech abnormalities" (p = 0.045). We found a negative correlation between the ICARS results and total cerebellar volume (r = -0.9, p = 0.037) in a group of five patients with available volumetric study, meaning that the higher the ICARS score, the more severe was the cerebellar atrophy. CONCLUSIONS: Our study shows a stabilization or mild improvement in the cerebellar functions of paediatric PMM2-CDG patients despite cerebellar volume loss. ICARS is a valid scale to quantify the evolution of cerebellar syndrome in PMM2-CDG patients. The availability of ICARS and other reliable and sensitive follow-up tools may prove essential for the evaluation of potential therapies.