Germline bi-allelic SH2B3/LNK alteration predisposes to a neonatal juvenile myelomonocytic leukemia-like disorder.

Juvenile myelomonocytic leukemia (JMML) is a rare, generally aggressive myeloproliferative neoplasm affecting young children. It is characterized by granulomonocytic expansion, with monocytosis infiltrating peripheral tissues. JMML is initiated by mutations upregulating RAS signaling. Approximately 10% of cases remain without an identified driver event. Exome sequencing of 2 unrelated cases of familial JMML of unknown genetics and analysis of the French JMML cohort identified 11 patients with variants in SH2B3, encoding LNK, a negative regulator of the JAK-STAT pathway. All variants were absent from healthy population databases, and mutation spectrum was consistent with a loss of function of the LNK protein. A stoploss variant was shown to affect both protein synthesis and stability. The other variants were either truncating or missense, the latter affecting the SH2 domain that interacts with activated JAK. Of the 11 patients, 8 from 5 families inherited pathogenic bi-allelic SH2B3 germline variants from their unaffected heterozygous parents. These children represent half of the cases with no identified causal mutation in the French cohort. They displayed typical clinical and hematological JMML features with neonatal onset and marked thrombocytopenia. They were characterized by absence of additional genetic alterations and a hypomethylated DNA profile with fetal characteristics. All patients showed partial or complete spontaneous clinical resolution. However, progression to thrombocythemia and immunity-related pathologies may be of concern later in life. Bi-allelic SH2B3 germline mutations thus define a new condition predisposing to a JMML-like disorder, suggesting that the JAK pathway deregulation is capable of initiating JMML, and opening new therapeutic options.

SHH medulloblastoma and very early onset of bowel polyps in a child with PTEN hamartoma tumor syndrome.

Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a cancer predisposition syndrome characterized by an increased risk of developing benign and malignant tumors, caused by germline pathogenic variants of the PTEN tumour suppressor gene. PTEN gene variants often present in childhood with macrocephaly, developmental delay, and/or autism spectrum disorder while tumors and intestinal polyps are commonly detected in adults. PHTS is rarely associated with childhood brain tumors with only two reported cases of medulloblastoma (MB). We report the exceptional case of an infant carrying a germline and somatic pathogenic variant of PTEN and a germline and somatic pathogenic variant of CHEK2 who developed a MB SHH in addition to intestinal polyposis.

Long-term follow-up in a pediatric patient with Ligneous Conjunctivitis due to PLG gene mutation in topical plasminogen treatment after successful use of ocular prosthesis for aesthetic rehabilitation: a case report.

BACKGROUND: Ligneous Conjunctivitis (LC) is the most common clinical manifestation of Type I Plasminogen deficiency (T1PD; OMIM# 217090), and it is characterized by the formation of pseudomembranes (due to deposition of fibrin) on the conjunctivae leading to progressive vision loss. In past times, patients with LC were treated with surgery, topical anti-inflammatory, cytostatic agents, and systemic immunosuppressive drugs with limited results (Blood 108:3021-3026, 2006, Ophthalmology 129:955-957, 2022, Surv Ophthalmol 48:369-388, 2003, Blood 131:1301-1310, 2018). The surgery can also trigger the development of membranes, as observed in patients needing ocular prosthesis (Surv Ophthalmol 48:369-388, 2003). Treatment with topical purified plasminogen is used to prevent pseudomembranes formation (Blood 108:3021-3026, 2006, Ophthalmology 129:955-957, 2022). CASE PRESENTATION: We present the case of a sixteen-year-old girl with LC with severe left eye involvement. We reported the clinical conditions of the patient before and after the use of topical plasminogen eye drops and described the treatment schedule allowing the surgical procedure for the pseudomembranes debulking and the subsequent use of ocular prosthesis for aesthetic rehabilitation. CONCLUSIONS: The patient showed a progressive response to the topical plasminogen, with a complete absence of pseudomembrane formation at a twelve-year follow-up, despite using an ocular prosthesis.

Congenital heart defects in CTNNB1 syndrome: Raising clinical awareness.

CTNNB1 [OMIM *116806] encodes ß-catenin, an integral part of the cadherin/catenin complex, which functions as effector of Wnt signaling. CTNNB1 is highly expressed in brain as well as in other tissues, including heart. Heterozygous CTNNB1 pathogenic variations are associated with a neurodevelopmental disorder characterized by spastic diplegia and visual defects (NEDSDV) [OMIM #615075], featuring psychomotor delay, intellectual disability, behavioral disturbances, movement disorders, visual defects and subtle facial and somatic features. We report on a new series of 19 NEDSDV patients (mean age 10.3 years), nine of whom bearing novel CTNNB1 variants. Notably, five patients showed congenital heart anomalies including absent pulmonary valve with intact ventricular septum, atrioventricular canal with hypoplastic aortic arch, tetralogy of Fallot, and mitral valve prolapse. We focused on the cardiac phenotype characterizing such cases and reviewed the congenital heart defects in previously reported NEDSDV patients. While congenital heart defects had occasionally been reported so far, the present findings configure a higher rate of cardiac anomalies, suggesting dedicated heart examination to NEDSDV clinical management.

Performance Metrics of the Scoring System for the Diagnosis of the Beckwith-Wiedemann Spectrum (BWSp) and Its Correlation with Cancer Development.

Different scoring systems for the clinical diagnosis of the Beckwith-Wiedemann spectrum (BWSp) have been developed over time, the most recent being the international consensus score. Here we try to validate and provide data on the performance metrics of these scoring systems of the 2018 international consensus and the previous ones, relating them to BWSp features, molecular tests, and the probability of cancer development in a cohort of 831 patients. The consensus scoring system had the best performance (sensitivity 0.85 and specificity 0.43). In our cohort, the diagnostic yield of tests on blood-extracted DNA was low in patients with a low consensus score (~20% with a score = 2), and the score did not correlate with cancer development. We observed hepatoblastoma (HB) in 4.3% of patients with UPD(11)pat and Wilms tumor in 1.9% of patients with isolated lateralized overgrowth (ILO). We validated the efficacy of the currently used consensus score for BWSp clinical diagnosis. Based on our observation, a first-tier analysis of tissue-extracted DNA in patients with <4 points may be considered. We discourage the use of the consensus score value as an indicator of the probability of cancer development. Moreover, we suggest considering cancer screening for negative patients with ILO (risk ~2%) and HB screening for patients with UPD(11)pat (risk ~4%).

Safety and Efficacy of Mek Inhibitors in the Treatment of Plexiform Neurofibromas: A Retrospective Study.

INTRODUCTION: Plexiform neurofibromas (PN) represent the main cause of morbidity in patients affected by Neurofibromatosis Type 1 (NF1). Until recently, surgery has been the main treatment option in these patients, but it is burdened with a low efficacy rate and a high incidence of side effects as well as recurrence. In recent years, MEK inhibitors (MEKi) such as selumetinib and trametinib have shown great promise. METHODS: We retrospectively describe a single center cohort of NF1 patients affected by PN1 and treated with MEKi since 2019 to 2021. Patients recruited in the study were affected by PN that were not eligible to complete surgical excision, symptomatic or with major cosmetic deformation or functional neurological deficits. RESULTS: Most patients experienced improvement in clinical symptoms and quality of life, with reduction or stabilization of lesions. However, no complete response was achieved. The most common adverse effects involved the skin, affecting every patient. Importantly, no life-threatening adverse effects occurred. CONCLUSIONS: In our experience, MEKi treatment has been shown to be both safe and effective in improving symptomatology and quality of life.

Deleterious, protein-altering variants in the transcriptional coregulator ZMYM3 in 27 individuals with a neurodevelopmental delay phenotype.

Neurodevelopmental disorders (NDDs) result from highly penetrant variation in hundreds of different genes, some of which have not yet been identified. Using the MatchMaker Exchange, we assembled a cohort of 27 individuals with rare, protein-altering variation in the transcriptional coregulator ZMYM3, located on the X chromosome. Most (n = 24) individuals were males, 17 of which have a maternally inherited variant; six individuals (4 male, 2 female) harbor de novo variants. Overlapping features included developmental delay, intellectual disability, behavioral abnormalities, and a specific facial gestalt in a subset of males. Variants in almost all individuals (n = 26) are missense, including six that recurrently affect two residues. Four unrelated probands were identified with inherited variation affecting Arg441, a site at which variation has been previously seen in NDD-affected siblings, and two individuals have de novo variation resulting in p.Arg1294Cys (c.3880C>T). All variants affect evolutionarily conserved sites, and most are predicted to damage protein structure or function. ZMYM3 is relatively intolerant to variation in the general population, is widely expressed across human tissues, and encodes a component of the KDM1A-RCOR1 chromatin-modifying complex. ChIP-seq experiments on one variant, p.Arg1274Trp, indicate dramatically reduced genomic occupancy, supporting a hypomorphic effect. While we are unable to perform statistical evaluations to definitively support a causative role for variation in ZMYM3, the totality of the evidence, including 27 affected individuals, recurrent variation at two codons, overlapping phenotypic features, protein-modeling data, evolutionary constraint, and experimentally confirmed functional effects strongly support ZMYM3 as an NDD-associated gene.

Exploiting in silico structural analysis to introduce emerging genotype-phenotype correlations in DHCR24-related sterol biosynthesis disorder: a case study.

Desmosterolosis is a rare sterol biosynthesis disorder characterized by multiple congenital anomalies, failure to thrive, severe developmental delay, progressive epileptic encephalopathy, and elevated levels of desmosterol caused by biallelic mutations of DHCR24 encoding 3-ß-hydroxysterol Δ-24-reductase. DHCR24 is regarded as the key enzyme of cholesterol synthesis in the metabolism of brain cholesterol as it catalyzes the reduction of the Δ-24 double bond of sterol intermediates during cholesterol biosynthesis. To date, 15 DHCR24 variants, detected in 2 related and 14 unrelated patients, have been associated with the desmosterolosis disorder. Here, we describe a proband harboring the never-described DHCR24 homozygous missense variant NM_014762.4:c.506T>C, NP_055577.1:p.M169T, whose functional validation was confirmed through biochemical assay. By using molecular dynamics simulation techniques, we investigated the impact of this variant on the protein stability and interaction network with the flavin adenine dinucleotide cofactor, thereby providing a preliminary assessment of its mechanistic role in comparison to all known pathogenic variants, the wild-type protein, and a known benign DHCR24 variant. This report expands the clinical and molecular spectra of the DHCR24-related disorder, reports on a novel DHCR24 deleterious variant associated with desmosterolosis, and gives new insights into genotype-phenotype correlations.

Dominant ARF3 variants disrupt Golgi integrity and cause a neurodevelopmental disorder recapitulated in zebrafish.

Vesicle biogenesis, trafficking and signaling via Endoplasmic reticulum-Golgi network support essential developmental processes and their disruption lead to neurodevelopmental disorders and neurodegeneration. We report that de novo missense variants in ARF3, encoding a small GTPase regulating Golgi dynamics, cause a developmental disease in humans impairing nervous system and skeletal formation. Microcephaly-associated ARF3 variants affect residues within the guanine nucleotide binding pocket and variably perturb protein stability and GTP/GDP binding. Functional analysis demonstrates variably disruptive consequences of ARF3 variants on Golgi morphology, vesicles assembly and trafficking. Disease modeling in zebrafish validates further the dominant behavior of the mutants and their differential impact on brain and body plan formation, recapitulating the variable disease expression. In-depth in vivo analyses traces back impaired neural precursors' proliferation and planar cell polarity-dependent cell movements as the earliest detectable effects. Our findings document a key role of ARF3 in Golgi function and demonstrate its pleiotropic impact on development.

Expanding phenotype of FAM111B-related disease focusing on liver involvement: Literature review, report of a case with end-stage liver disease and proposal for a new acronym.

POIKiloderma, tendon contractures, myopathy, pulmonary fibrosis is a congenital multisystem disorder due to FAM111B dominant variants. We present a literature review focusing on the frequency and the impact of hepatic involvement and a case report of a patient with severe end-stage liver disease. Whole exome sequencing (WES) was conducted on the proband and his parents. A de novo FAM111B: c.1879A > G; (p.Arg627Gly) variant was identified. Hepatic involvement is present in 11 out of the 30 patients described in the literature, with different levels of dysfunction ranging from mild transaminitis to liver fibrosis found in three different cases by liver biopsies. Liver involvement seems to be a significant cause of morbidity. We propose to modify the previous acronym in POIK-TMPL: including POIKiloderma, tendon contractures, myopathy, pulmonary fibrosis/pancreas insufficiency and cancer, liver involvement/lymphedema. Moreover, we suggest screening patients with FAM111B variants for liver involvement from the first month of life and continue with an appropriate follow-up. Further studies are needed to better understand this frequent complication.

Characterization of Cognitive, Language and Adaptive Profiles of Children and Adolescents with Malan Syndrome.

Malan Syndrome (MS) is an ultra-rare overgrowth genetic syndrome due to heterozygous variants or deletions in the Nuclear Factor I X (NFIX) gene. It is characterized by an unusual facial phenotype, generalized overgrowth, intellectual disability (ID) and behavioral problems. Even though limitations in cognitive and adaptive functioning have been previously described, systematic studies on MS cohorts are still lacking. Here, we aim to define the cognitive and adaptive behavior profile of MS children and adolescents, providing quantitative data from standardized evaluations. Subjects included in this study were evaluated from October 2020 to January 2022 and the study is based on a retrospective data archive: fifteen MS individuals were recruited and underwent evaluation with Wechsler Intelligence Scales, Leiter International Performance Scales and Griffith Mental Development Scales for cognitive profiles and with Vineland Adaptive Behavior Scales-II Edition (VABS-II) for adaptive functioning. Language skills and visuomotor integration abilities were assessed too. Comparisons and correlations between scales and subtests were performed. All the assessed MS individuals showed both low cognitive and adaptive functioning. One subject presented with mild ID, five had moderate ID and eight showed severe ID. One female toddler received a diagnosis of psychomotor delay. Linguistic skills were impaired in all individuals, with language comprehension relatively more preserved. Results revealed significant differences between VABS-II subdomains and a strong relationship between cognitive and adaptive functioning. All subjects exhibited mild to moderate ID and adaptive behavior lower than normal, with communication skills being the most affected. Regarding the daily living skills domain, personal and community subscale scores were dramatically lower than for the domestic subdomain, highlighting the importance of considering behavior within developmental and environmental contexts. Our cognitive and adaptive MS characterization provides a more accurate quantitative MS profiling, which is expected to help clinicians to better understand the complexity of this rare disorder.

Clinical and molecular characterization of patients affected by Beckwith-Wiedemann spectrum conceived through assisted reproduction techniques.

The prevalence of Beckwith-Wiedemann spectrum (BWSp) is tenfold increased in children conceived through assisted reproductive techniques (ART). More than 90% of ART-BWSp patients reported so far display imprinting center 2 loss-of-methylations (IC2-LoM), versus 50% of naturally conceived BWSp patients. We describe a cohort of 74 ART-BWSp patients comparing their features with a cohort of naturally conceived BWSp patients, with the ART-BWSp patients previously described in literature, and with the general population of children born from ART. We found that the distribution of UPD(11)pat was not significantly different in ART and naturally conceived patients. We observed 68.9% of IC2-LoM and 16.2% of mosaic UPD(11)pat in our ART cohort, that strongly differ from the figure reported in other cohorts so far. Since UPD(11)pat likely results from post-fertilization recombination events, our findings allows to hypothesize that more complex molecular mechanisms, besides methylation disturbances, may underlie BWSp increased risk in ART pregnancies. Moreover, comparing the clinical features of ART and non-ART BWSp patients, we found that ART-BWSp patients might have a milder phenotype. Finally, our data show a progressive increase in the prevalence of BWSp over time, paralleling that of ART usage in the last decades.

A deep phenotyping experience: up to date in management and diagnosis of Malan syndrome in a single center surveillance report.

BACKGROUND: Malan syndrome (MALNS) is a recently described ultrarare syndrome lacking guidelines for diagnosis, management and monitoring of evolutive complications. Less than 90 patients are reported in the literature and limited clinical information are available to assure a proper health surveillance. RESULTS: A multidisciplinary team with high expertise in MALNS has been launched at the "Ospedale Pediatrico Bambino Gesù", Rome, Italy. Sixteen Italian MALNS individuals with molecular confirmed clinical diagnosis of MALNS were enrolled in the program. For all patients, 1-year surveillance in a dedicated outpatient Clinic was attained. The expert panel group enrolled 16 patients and performed a deep phenotyping analysis directed to clinically profiling the disorder and performing critical revision of previously reported individuals. Some evolutive complications were also assessed. Previously unappreciated features (e.g., high risk of bone fractures in childhood, neurological/neurovegetative symptoms, noise sensitivity and Chiari malformation type 1) requiring active surveillance were identified. A second case of neoplasm was recorded. No major cardiovascular anomalies were noticed. An accurate clinical description of 9 new MALNS cases was provided. CONCLUSIONS: Deep phenotyping has provided a more accurate characterization of the main clinical features of MALNS and allows broadening the spectrum of disease. A minimal dataset of clinical evaluations and follow-up timeline has been proposed for proper management of patients affected by this ultrarare disorder.

Expanding the novel MAPKAPK5-related developmental disorder's genotype-phenotype correlation: Patient report and 19 months of follow-up.

This study aimed to widen the knowledge of a recently identified, autosomal-recessive, multiple congenital anomalies syndrome to date observed in only other three children. This is the second report of biallelic mutations in MAPKAPK5 whose impairment during human development has been associated with neurological, cardiac, and facial anomalies combined with fingers and toes malformations. Through the affected patients' genetic and phenotypic features overlap, this report confirms MAPKAPK5 as causative gene and adds unique neurodevelopmental characterization. Moreover, based on the complex congenital genitourinary anomalies reported and MAPKAPK5 literature review, we also propose kidney and external genitalia involvement as a key syndromic feature whose expressivity may be more severe in males.

Synchronous Presentation of Rare Brain Tumors in Von Hippel-Lindau Syndrome.

Von Hippel-Lindau (VHL) disease is a heritable cancer syndrome in which benign and malignant tumors and/or cysts develop throughout the central nervous system (CNS) and visceral organs. The disease results from mutations in the VHL tumor suppressor gene located on chromosome 3 (3p25-26). A majority of individuals (60-80%) with VHL disease will develop CNS hemangioblastomas (HMG). Endolymphatic sac tumor (ELST) is an uncommon, locally aggressive tumor located in the medial and posterior petrosal bone region. Its diagnosis is based on clinical, radiological, and pathological correlation, and it can occur in the setting of VHL in up to 10-15% of individuals. We describe a 17-year-old male who presented with a chief complaint of hearing loss. Brain and spine Magnetic Resonance Imaging documented the presence of an expansive lesion in the left cerebellar hemisphere, compatible with HMG in association with a second cerebellopontine lesion compatible with ELST. The peculiarity of the reported case is due to the simultaneous presence of two typical characteristics of VHL, which led to performing comprehensive genetic testing, thus allowing for the diagnosis of VHL. Furthermore, ELST is rare before the fourth decade of life. Early detection of these tumors plays a key role in the optimal management of this condition.

Phenotypic expansion of CACNA1C-associated disorders to include isolated neurological manifestations.

PURPOSE: CACNA1C encodes the alpha-1-subunit of a voltage-dependent L-type calcium channel expressed in human heart and brain. Heterozygous variants in CACNA1C have previously been reported in association with Timothy syndrome and long QT syndrome. Several case reports have suggested that CACNA1C variation may also be associated with a primarily neurological phenotype. METHODS: We describe 25 individuals from 22 families with heterozygous variants in CACNA1C, who present with predominantly neurological manifestations. RESULTS: Fourteen individuals have de novo, nontruncating variants and present variably with developmental delays, intellectual disability, autism, hypotonia, ataxia, and epilepsy. Functional studies of a subgroup of missense variants via patch clamp experiments demonstrated differential effects on channel function in vitro, including loss of function (p.Leu1408Val), neutral effect (p.Leu614Arg), and gain of function (p.Leu657Phe, p.Leu614Pro). The remaining 11 individuals from eight families have truncating variants in CACNA1C. The majority of these individuals have expressive language deficits, and half have autism. CONCLUSION: We expand the phenotype associated with CACNA1C variants to include neurodevelopmental abnormalities and epilepsy, in the absence of classic features of Timothy syndrome or long QT syndrome.