Distinctive Dysmorphic Features Research Articles

Biotinidase Deficiency and Aplasia Cutis Congenita with Ecterodactyly Syndrome (ACCES) in a case of Moya Moya Disease: A Missing Link

Biotinidase Deficiency (BD) is a rare autosomal recessive disorder caused by mutations in the BTD gene, leading to impaired biotin recycling and disruption in energy metabolism, oxidative stress, and blood-brain barrier function. This condition increases the risk of neurovascular events such as strokes. In parallel, the UBA2 gene's loss of function, through various mutations, results in Aplasia Cutis Congenita with Ectrodactyly (ACCES) syndrome, an autosomal dominant disorder with highly variable expressivity. ACCES syndrome commonly presents with scalp defects and less frequently with ectrodactyly, alongside other subtle skeletal anomalies, early growth deficiency, and neurodevelopmental delay. This case report discusses a 6-year-old child presenting with an acute stroke and distinct dysmorphic features, highlighting a rare association between Biotinidase Deficiency and ACCES syndrome, which likely contributed to the development of Moya Moya Disease (MMD), a rare progressive cerebrovascular disorder. The case suggests that the combination of neurovascular stress due to both BD and ACCES may increase the risk of stroke and MMD in affected individuals. This underscores the importance of recognizing overlapping genetic conditions that could lead to severe neurovascular complications.

Identification of a Novel Frameshift variant of the ATRX gene: a Case Report and Review of the genotype–phenotype relationship

BackgroundX-linked intellectual disability-hypotonic facies syndrome-1 (MRXHF1) and Alpha-thalassemia X-linked intellectual disability (ATR-X) syndrome are caused by pathogenic variant in the ATRX gene, a member of the switch/sucrose non-fermentable (SWI-SNF) protein family that exhibits chromatin remodeling activity. These syndromes show a wide spectrum of clinical manifestations, such as distinctive dysmorphic features, mild-to-profound intellectual disability, motor development delay, seizures, urogenital abnormalities, and gastrointestinal disorders.Case presentation and literature reviewA 3-year-old boy from a Chinese non-consanguineous family was diagnosed with MRXHF1 by whole-exome sequencing. Comprehensive family history information was obtained. The Medline database was searched until 1st Aug 2023 for articles related to ATRX pathogenic variant. Data on gene/protein mutations and clinical symptoms were extracted. The proband showed intellectual disability, motor development delay, typical facial abnormalities, urogenital defect, behavior problems, and optical nerve dysplasia. A novel frameshift mutation c.399_400dup, (p.Leu134Cysfs*2) in the ATRX gene was the primary cause, which occurs right before the ATRXDNMT3-DNMT3L (ADD) domain of ATRX protein. Missense mutation is the most common variation type. The ADD and helicase-like domains are the most frequently affected domains. Epilepsy, congenital heart disease, urogenital defect, acoustic defect, and optical defect are more prevalent in patients with frameshift mutations compared to those with missense mutations. There are more urogenital defects with C-terminal frameshift mutations than with N-terminal frameshift mutations.ConclusionWe described a novel frameshift mutation in the ATRX gene in a patient with MRXHF1 syndrome and summarized the genotype–phenotype relationship of ATRX pathogenic variant by variation type and affected protein domain. The regulatory mechanism underlying ATRX variant requires comprehensive analysis in future studies.

Smith-Magenis Syndrome associated with Autism Spectrum Disorder with delayed diagnosis due to B12 deficiency: a case report

IntroductionSmith-Magenis syndrome (SMS) is a complex genetic disorder characterised by distinctive physical features, developmental delay, cognitive impairment and a typical behavioural phenotype. SMS is caused by interstitial 17p11.2 deletions (90%) involving multiple genes, including the retinoic acid-induced 1 gene (RAI1), or by pathogenic variants in RAI1 itself (10%).ObjectivesIn this case report, we present a case of Smith-Magenis syndrome with Autism Spectrum Disorder with karyotype 46,XX, 17p 11.2 gene deletion confirmed by Autism Spectrum Disorder, who was followed up in a paediatric neurology outpatient clinic with neuromotor developmental delay and whose diagnosis was delayed due to B12 deficiency. We also update scientific developments in Smith-Magenis syndrome.MethodsWe describe an 18-month-old male with Smith-Magenis syndrome and Autism Spectrum Disorder who was seen in our paediatric psychiatric outpatient clinic and who received B12 replacement with developmental delay.ResultsThe patient was followed up in the paediatric neurology outpatient clinic with delay in neuromotor developmental milestones and this delay was thought to be due to B12 deficiency (B12<100 ng/L). The initial examination revealed delay in neuromotor and behavioural milestones, speech delay, wide and high nasal bridge and hypertelorism. Further physical examination revealed syndactyly of the second and third toes bilaterally and crossed lower teeth. Clinical and psychometric testing (Ankara Developmental Screening Inventory) by 2 consultants and 1 research assistant resulted in a diagnosis of intellectual disability and an additional diagnosis of Autism Spectrum Disorder due to social deficits that could not be explained by intellectual disability.ConclusionsSmith-Magenis syndrome is a well-known disorder involving the deletion of chromosome 17p11.2, which contains the RAI1 gene. This condition is associated with neuromotor and behavioural delay, as well as distinctive dysmorphic features. Clinicians should consider Smith-Magenis syndrome in the differential diagnosis for patients with delayed neuromotor and behavioural milestones, even in the presence of documented blood parameters (such as B12 deficiency) that may account for the delay.Disclosure of InterestNone Declared

De novo KAT6B mutation causes Say–Barber–Biesecker–Young–Simpson variant of Ohdo syndrome in an Iranian boy: a case report

BackgroundSay–Barber–Biesecker–Young–Simpson (SBBYS) (OMIM #603736, Ohdo syndrome variant) is a rare type of severe blepharophimosis intellectual disability syndrome, which is generally characterized by a global developmental delay, distinctive facial features, and intellectual disability with multiple congenital anomalies, including skeletal involvement, missing, or underdeveloped kneecaps, and genital anomalies, in affected males. It has been shown that mutations in the KAT6B gene, which is a lysine acetyltransferase-encoding gene, have been associated with SBBYS syndrome. All the known variants are dominant de novo mutations that result in protein truncation.Case presentationA 14-year-old Iranian Azeri boy with an intellectual disability, distinct dysmorphic facial features such as open-mouth expression, sparse medial eyebrows, widely spaced upward-slanted eyes, epicanthal folds, broad nasal bridge, low-set ears, anteverted ears, short philtrum, hypertelorism, microphthalmia is presented in this case study. Cryptorchidism was reported. Neurologically, the patient presented with poor eye contact, hypotonia, and speech difficulties. In the skeletal X-ray, underdeveloped kneecaps with some new features were observed.ConclusionWe present the first case of SBBYS syndrome in association with some new anomaly features in the Iranian population. Based on this diagnosis, we could provide the patient with a suitable plan of management as well as appropriate genetic counseling for his family.

Hearing characteristics and otoradiological abnormalities in three patients with novel pathogenic variants of KMT2D-related Kabuki syndrome.

Kabuki syndrome 1 (KS1; OMIM:147920), which is characterized by distinctive dysmorphic facial features (such as arched eyebrows, long palpebral fissures with eversion of the lower lid, and large protuberant ears), intellectual disability, short stature, and dermatoglyphic and skeletal abnormalities, is brought on by pathogenic variants in KMT2D (OMIM:602113). In this work, three individuals with novel pathogenic KMT2D gene variants had their longitudinal audiological manifestations and ear structural characteristics outlined. The longitudinal audiological data from neonatal hearing screening and a battery of several hearing tests were evaluated. The battery of hearing tests included tympanometry, distortion product otoacoustic emission (DPOAE), click-evoked air-conduction auditory brain-stem response (AC-ABR), click-evoked bone-conduction auditory brain-stem response (BC-ABR), narrow band CE-chirp auditory steady-state response (NB CE-chirp ASSR), and pure-tone audiometry (PTA). Phenotype identification and whole exome sequencing (WES) were performed on recruited individuals. All three patients (two females and on male; last evaluations at 14 months, 11 months, and 5.7 years, respectively) failed the newborn hearing screening, and the audiological follow-up data revealed mild to profound fluctuating hearing loss, which was directly influenced by the incidence and severity of otitis media with effusion (OME). When OME occurred, the AC-ABR thresholds increased from 30-75 dBnHL to 45-90 dBnHL. The threshold for the BC-ABR and BC-PTA was between 25 and 50 dBnHL, indicating mild to moderate sensorineural hearing loss (SNHL). The high-resolution computed tomography (HRCT) pictures indicated that all three patients had middle and inner ear abnormalities. Middle ear anomalies showed as diminished mastoid gasification and ossicle dysplasia. Cochlear dysplasia, a dilated vestibule, fusion of the vestibule with the horizontal semicircular canals, and a short and thick horizontal semicircular canal were visible on images of the inner ear. This study recruited three individuals with three novel pathogenic variants (c.5104C>T, c.10205delA, and c.12840delC) of KMT2D who were identified at ages 27 days, 2 months, and 5.5 years. Hearing characteristics of three individuals with three novel pathogenic variants of KMT2D range from mild to profound fluctuating hearing loss with mild to moderate SNHL. HRCT scans showed that all three individuals had anatomical middle and inner ear abnormalities. KS 1 patients must get clinical therapy for OME, frequent auditory monitoring, and prompt intervention.

The epileptology of Wiedemann-Steiner syndrome: Electroclinical findings in five patients with KMT2A pathogenic variants.

Wiedemann-Steiner Syndrome (WSTS) is a rare chromatinopathy caused by pathogenic variants in KMT2A. WSTS is characterized by neurodevelopmental disorders and distinct dysmorphic features. Epilepsy has been reported in only 33 individuals with WSTS, with only limited clinical details described. We identified patients with pathogenic KMT2A variants and epilepsy, and performed thorough phenotyping. Five patients were identified, all of whom presented with developmental and epileptic encephalopathy (DEE). Epilepsy syndromes observed included Lennox-Gastaut syndrome [2], infantile epileptic spasms syndrome, and DEE with spike-wave activation in sleep. Seizure types observed included absence, generalized tonic-clonic, myoclonic, tonic, atonic, epileptic spasms, and focal seizures. The spectrum of epilepsy phenotypes in patients with WSTS can be broad, but presentation is typically severe, usually involving a form of DEE.

Genetically unresolved case of Rauch-Steindl syndrome diagnosed by its wolf-hirschhorn associated DNA methylation episignature.

Wolf-Hirschhorn syndrome (WHS) is caused by deletion of a critical region of the short arm of chromosome 4. Clinical features of WHS include distinct dysmorphic facial features, growth restriction, developmental delay, intellectual disability, epilepsy, and other malformations. The NSD2 gene localizes within this critical region along with several other genes. Pathogenic variants in NSD2 cause Rauch-Steindl (RAUST) syndrome. Clinical features of RAUST syndrome partially overlap with WHS, however epilepsy and the recognizable facial gestalt are not observed. Here, we report a case of a young boy who presented with developmental delay, dysmorphic features and short stature. After negative chromosomal microarray and whole exome sequencing, genomic DNA methylation episignature analysis was performed. Episignatures are sensitive and specific genome-wide DNA methylation patterns associated with a growing number of rare disorders. The patient was positive for the WHS episignature. Reanalysis of the patient's exome data identified a previously undetected frameshift variant in NSD2, leading to a diagnosis of RAUST. This report demonstrates the clinical utility of DNA methylation episignature analysis for unresolved patients, and provides insight into the overlapping pathology between WHS and RAUST as demonstrated by the similarities in their genomic DNA methylation profiles.

Interstitial Duplication on Chromosome 3p14.3p13 in an Adolescent with Dysmorphic Features and Autism, Case Report

Abstract Introduction/Objective The genetic etiology of autism spectrum disorders is only partially understood. Here we describe a 16-year-old male diagnosed with autism at two years of age. He has dysmorphic features, severe cognitive disability, and history of cryptorchidism. A review of systems was significant for slightly coarse features overall, with deep-set eyes, pinched nasal bridge with wide nasal tip, and widely spaced teeth. A large pectus excavatum deformity was also noted. Although the parent’s genetic testing concluded that this likely represents de novo mutation, it is worth mentioning that our patient has a 13-year-old female maternal first cousin with learning difficulties that were said to be less severe. There is no other family history of autism. Methods/Case Report Chromosome analysis showed an abnormal karyotype identifying a duplication of the short arm of chromosome 3 from p13 to p14.3, 46,XY,dup(3)(p13p14.3). Additional microarray testing confirmed this duplication and defined the size as 14.9 Mb. Regions of homozygosity of 29.8 Mb were also identified, representing about 1% of the autosomal genome. The duplicated area includes over 70 genes, thirteen of which are known Mendelian disease genes (IL17RD, HESX1, APPL1, FLNB, DNASEIL3, PDHB, ACOX2, ATXN7, SLC25A26, EOGT, LMOD3, MITF, and FOXP1). Duplications of 3p are extremely rare and can be de novo or inherited from a parent with a balanced translocation. Individuals with these better-described chromosome 3p duplications typically present with intellectual and developmental disabilities, such as autism, as 3p duplications typically present with intellectual and developmental disabilities, such as autism and distinctive dysmorphic features. This duplication has never been reported as a known syndrome and has minimal overlap with copy number variants (CNVs) among healthy individuals. Results (if a Case Study enter NA) NA Conclusion Autism spectrum disorders are largely characterized by speech, communication, and social impairment of varying degrees. Diagnosis is typically made on clinical grounds, but in 14-35% of cases, a genetic basis for the disorder, typically either due to a single gene disorder or a chromosomal deletion/duplication, may be found. This case report describes a rare finding of a 14.9 Mb interstitial duplication on chromosome 3p.

Hypoparathyroidism-retardation-dysmorphism syndrome-Clinical insights from a large longitudinal cohort in a single medical center.

BackgroundHypoparathyroidism, retardation, and dysmorphism (HRD) Syndrome is a rare disease composed of hypoparathyroidism, retardation of both growth and development, and distinctive dysmorphic features. Here, we describe the long-term morbidity and mortality in a large cohort of HRD patients and suggest recommendations for follow up and treatment.MethodsMedical records of 63 HRD syndrome patients who were followed at Soroka Medical Center during 1989–2019 were reviewed retrospectively. Information regarding demographics, medical complications, laboratory findings, and imaging studies was collected.ResultsThe mortality rate was 52%. The main causes of death were infectious diseases including pneumonia, septic shock, and meningitis. Multiple comorbidities were found including brain anomalies in 90% of examined patients (basal ganglia calcifications, tightening of corpus callosum, Chiari malformation, hydrocephalous, and brain atrophy), seizures in 62%, nephrocalcinosis and/or nephrolithiasis in 47%, multiple eye anomalies were recorded in 40%, bowel obstructions in 9.5%, and variable expression of both conductive and senso-neural hearing loss was documented in 9.5%.ConclusionHRD is a severe multisystem disease. Active surveillance is indicated to prevent and treat complications associated with this rare syndrome.

EP074: Atypical presentation of a patient with Sotos syndrome with later onset overgrowth, mandibular hypoplasia, and cleft palate

Sotos Syndrome is an overgrowth syndrome caused by pathogenic variants or deletions in NSD1 gene. Its typically characterized by overgrowth of prenatal onset with average birth length above 95%ile, distinctive dysmorphic features, and learning disability. Major systemic features include behavioral problems, cardiac abnormalities, musculoskeletal abnormalities including scoliosis and joints hyperlaxity, and cranial imaging abnormalities and seizures. Otolaryngological complications have been very rarely reported.

Kleefstra syndrome: Recurrence in siblings due to a paternal mosaic mutation

Kleefstra syndrome (KS) is a rare autosomic dominant genetic disorder caused by euchromatic histone methyltransferase 1 (EHMT1) alterations. Patients mainly present with moderate to severe intellectual disability, a severe delay in/or absence of speech, autism spectrum disorder, childhood hypotonia, neuropsychiatric anomalies, and distinctive dysmorphic features. Here, we report the cases of a male and a female, two younger siblings of three, with asymptomatic parents. An EHMT1 new mutation was identified. Both presented with a typical core phenotype. Some specific features were noted, such as macrocephaly (previously reported) and enuresis (not yet described). Parental analysis identified the mutation in the mosaic state in the father. Reverse phenotyping enabled us to highlight the pauci phenotype features of inguinal hernia, azoospermia, and possible behavioral disorders. This allowed us to adapt his follow-up and genetic counseling for the family. Our three reported cases provide a new description of KS with an intragenic EHMT1 mutation, whereas in the literature most reported cases have EHMT1 deletions. Moreover, in the areas of next-generation sequencing and trio techniques with parental segregation, it is important to remain cautious about disregarding variants based on an autosomal recessive hypothesis.

Delineation of the clinical and radiological features of Stuve–Wiedemann syndrome childhood survivors, four new cases and review of the literature

Stuve-Wiedemann syndrome (SWS; MIM 601559) is a rare autosomal recessive disease caused by mutations in the leukemia inhibitor factor receptor gene (LIFR). Common clinical and radiological findings are often observed, and high neonatal mortality occurs due to respiratory distress and hyperthermic episodes. Despite initially considered as a lethal disorder during the newborn period, in recent years, several SWS childhood survivors have been reported. We report a detailed clinical and radiological characterization of four unrelated childhood SWS molecularly confirmed patients and review 22 previously reported childhood surviving cases. We contribute to the definition of the childhood survival phenotype of SWS, emphasizing the evolving phenotype, characterized by skeletal abnormalities with typical radiological findings, distinctive dysmorphic features, and dysautonomia. Based on the typical features and clinical course, early diagnosis is possible and crucial to plan appropriate management and prevent potential complications. Genetic confirmation is advisable in order to improve genetic counseling to the patients and their families.

Effect of Growth Hormone Therapy in Patients with Noonan Syndrome: A Retrospective Study.

BackgroundNoonan syndrome is an autosomal dominant condition with an incidence of 1:1000 to 1:2500. The disorder is associated with distinct dysmorphic features, cardiac anomalies, developmental delay and delayed puberty. Short stature is a recognised feature of Noonan syndrome.ObjectivesThe aim of this study is to assess the effect of growth hormone treatment in patients with Noonan syndrome.MethodsRetrospective data was collected from patients with Noonan syndrome treated with growth hormone. The results were analysed with variables expressed as mean values and standard deviation scores.ResultsTwelve Noonan syndrome patients (M: F = 10:2) treated with growth hormone were identified. The mean age of starting growth hormone was 8 years, with baseline height standard deviation score of -2.96 (range: -1.64 to -5.54). The height standard deviation score significantly improved to -2.50 (P = 0.0035) and then -2.22 (P = 0.0025), following one and two years of treatment, respectively. The average height velocity for the patients prior to starting treatment was 5.16cm/year (range: 2.4 - 8.2 cm/year), which significantly improved to 7.76cm/year (ranging from 4.1 to 12.8 cm/year) after one year of growth hormone treatment (P = 0.020) and to 6.51cm/year at the end of two years.ConclusionsOur study has shown that growth hormone treatment significantly improves the height standard deviation score of patients with Noonan syndrome over a two-year course of growth hormone therapy without any side effects. Further research is required to analyse the long-term effect of growth hormone therapy in patients with Noonan syndrome, including the impact on final adult height.

Proposed Phenotype for Females with a SETD5 Gene Variation: A Case Report

Background: SET domain containing 5 (SETD5) gene variants have been linked to developmental delays, craniofacial abnormalities, and intellectual disability (ID). Prior research examining the phenotypic presentation of individuals with SETD5 variations has been based largely on a male-dominated cohort and case studies. Evidence of a possible protective effect in females prompts the need for additional research on the neuropsychological presentation of females with a SETD5 variation. The current study aims to initiate this effort by discussing the neurocognitive profile of a right-handed 7-year-old Caucasian female with a diagnosed SETD5 variation. Methods and findings: The patient was referred for neuropsychological evaluation due to reported reading, writing, and fine motor difficulties. She presented with distinct dysmorphic features: head circumference <1st percentile, syndactyly of toes, clinodactyly of fifth fingers, and a long smooth philtrum with thin upper lip. Interpersonally, the patient was highly social. Cognitive testing revealed low average intelligence, with intact verbal/language functioning and impaired nonverbal/fluid reasoning abilities. Deficits were also observed in fine motor dexterity, visuomotor integration, attention, and broad academic achievement. The patient was ultimately referred for genetic testing, which revealed a de novo SETD5 frame shift variant resulting in a truncation of the gene copy near the end of the gene. Conclusion: This case study provides evidence for phenotypic differences between males and females with SETD5 gene variations. While males exhibit ID, females may present with significant deficits in nonverbal reasoning skills. Females may also display more fully developed social skills and a lack of repetitive stereotyped behaviors. Further research is warranted to clarify the unique presentation among females with SETD5 variations to better inform diagnosis and treatment planning.

HNRNPH1-related syndromic intellectual disability: Seven additional cases suggestive of a distinct syndromic neurodevelopmental syndrome.

Pathogenic variants in HNRNPH1 were first reported in 2018. The reported individual, a 13 year old boy with a c.616C>T (p.R206W) variant in the HNRNPH1 gene, was noted to have overlapping symptoms with those observed in HNRNPH2-related X-linked intellectual disability, Bain type (MRXSB), specifically intellectual disability and dysmorphic features. While HNRNPH1 variants were initially proposed to represent an autosomal cause of MRXSB, we report an additional seven cases which identify phenotypic differences from MRXSB. Patients with HNRNPH1 pathogenic variants diagnosed via WES were identified using clinical networks and GeneMatcher. Features unique to individuals with HNRNPH1 variants include distinctive dysmorphic facial features; an increased incidence of congenital anomalies including cranial and brain abnormalities, genitourinary malformations, and palate abnormalities; increased incidence of ophthalmologic abnormalities; and a decreased incidence of epilepsy and cardiac defects compared to those with MRXSB. This suggests that pathogenic variants in HNRNPH1 result in a related, but distinct syndromic cause of intellectual disability from MRXSB, which we refer to as HNRNPH1-related syndromic intellectual disability.

Phenotypic expansion of KMT2D-related disorder: Beyond Kabuki syndrome.

Pathogenic variants in KMT2D, which encodes lysine specific methyltransferase 2D, cause autosomal dominant Kabuki syndrome, associated with distinctive dysmorphic features including arched eyebrows, long palpebral fissures with eversion of the lower lid, large protuberant ears, and fetal finger pads. Most disease-causing variants identified to date are putative loss-of-function alleles, although 15-20% of cases are attributed to missense variants. We describe here four patients (including one previously published patient) with de novo KMT2D missense variants and with shared but unusual clinical findings not typically seen in Kabuki syndrome, including athelia (absent nipples), choanal atresia, hypoparathyroidism, delayed or absent pubertal development, and extreme short stature. These individuals also lack the typical dysmorphic facial features found in Kabuki syndrome. Two of the four patients had severe interstitial lung disease. All of these variants cluster within a 40-amino-acid region of the protein that is located just N-terminal of an annotated coiled coil domain. These findings significantly expand the phenotypic spectrum of features associated with variants in KMT2D beyond those seen in Kabuki syndrome and suggest a possible new underlying disease mechanism for these patients.

Infantile-Onset Syndromic Cerebellar Ataxia and CACNA1G Mutations

BackgroundCongenital ataxias associated with cerebellar atrophy are clinically heterogeneous conditions with a variable age of onset and a diverse molecular basis. The hypothesis-free approach of genomic sequencing has led to the discovery of new genes implicated in these disorders and the identification of unexpected genotype–phenotype correlations. Although a recurrent heterozygous mutation (p.Arg1715His) in CACNA1G is known to cause adult-onset spinocerebellar ataxia 42 (SCA42*616795), gain-of-function mutations in this gene have recently been identified by whole exome sequencing (WES) in four children with cerebellar atrophy and ataxia, psychomotor delay, and other variable features. MethodsWe describe four children from unrelated families with cerebellar anomalies on magnetic resonance imaging (atrophy or hypoplasia of the cerebellar vermis), hypertonia, psychomotor and speech delay, severe intellectual disability, ophthalmologic features and peculiar dysmorphic traits. All patients underwent a trio-based WES analysis. Clinical records were used to characterize the clinical profile of this newly recognized disorder. ResultsTwo previously reported de novo disease-causing mutations in CACNA1G (c.2881G>A, p.Ala961Thr and c.4591A>G, p.Met1531Val) were identified in these patients, providing further evidence of the specific impact of these variants. All four patients exhibit distinctive dysmorphic and ectodermal features which overlap those of the previously reported patients, allowing us to define the major features characterizing this homogeneous neurodevelopmental syndromic disorder associated with upregulated CACNA1G function. ConclusionOur findings confirm the specific association between a narrow spectrum of missense mutations in CACNA1G and a novel syndrome with infantile-onset cerebellar ataxiaand provide a dysmorphologic delineation of this novel neurodevelopmental trait.

Correction to: Novel mutations in KMT2B offer pathophysiological insights on childhood-onset progressive dystonia

Rapid progress has recently been made in the elucidation of the genetic basis of childhood-onset inherited generalized dystonia (IGD) due to the implementation of genomic sequencing methodologies. We identified four patients with childhood-onset IGD harboring novel disease-causing mutations in lysine-specific histone methyltransferase 2B gene (KMT2B) by whole-exome sequencing. The main focus of this paper is to gain novel pathophysiological insights through understanding the molecular consequences of these mutations.The disease course is mostly progressive, evolving from lower limbs into generalized dystonia, which could be associated with dysarthria, dysphonia, intellectual disability, orofacial dyskinesia, and sometimes distinct dysmorphic facial features. In two patients, motor performances improved after bilateral implantation of deep brain stimulation in the globus pallidus internus (GPi-DBS). Pharmacotherapy with trihexyphenidyl reduced dystonia in two patients.We discovered three novel KMT2B mutations. Our analyses revealed that the mutation in patient 1 (c.7463 A > G, p.Y2488C) is localized in the highly conserved FYRC domain of KMT2B. This mutation holds the potential to alter the inter-domain FYR interactions, which could lead to KMT2B instability. The mutations in patients 2 and 3 (c.3602dupC, p.M1202Dfs*22; c.4229delA, p.Q1410Rfs*12) lead to predicted unstable transcripts, likely to be subject to degradation by non-sense mediated decay.Childhood-onset progressive dystonia with orofacial involvement is one of the main clinical manifestations of KMT2B mutations. In all, 26% (18/69) of the reported cases have T2 signal alterations of the globus pallidus internus, mostly at a younger age. Anticholinergic medication and GPi-DBS are promising treatment options and shall be considered early.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Delayed diagnosed atypical case of Andersen-Tawil syndrome.

Andersen-Tawil syndrome (ATS) is characterized by a triad of periodic paralysis, cardiac arrhythmias and distinctive dysmorphic features. Due to its rarity and high degree of clinical and phenotypic variability, a diagnosis of ATS can be very perplexing and challenging. Herein, an atypical case of ATS with a complicated presentation that caused an approximately 11-year delay in diagnosis is reported. The patient made a full recovery with acetazolamide after the diagnosis. The case and its management are presented with an updated literature review.

Novel mutations in KMT2B offer pathophysiological insights into childhood-onset progressive dystonia.

Rapid progress has recently been made in the elucidation of the genetic basis of childhood-onset inherited generalized dystonia (IGD) due to the implementation of genomic sequencing methodologies. We identified four patients with childhood-onset IGD harboring novel disease-causing mutations in lysine-specific histone methyltransferase 2B gene (KMT2B) by whole-exome sequencing. The main focus of this paper is to gain novel pathophysiological insights through understanding the molecular consequences of these mutations. The disease course is mostly progressive, evolving from lower limbs into generalized dystonia, which could be associated with dysarthria, dysphonia, intellectual disability, orofacial dyskinesia, and sometimes distinct dysmorphic facial features. In two patients, motor performances improved after bilateral implantation of deep brain stimulation in the globus pallidus internus (GPi-DBS). Pharmacotherapy with trihexyphenidyl reduced dystonia in two patients. We discovered three novel KMT2B mutations. Our analyses revealed that the mutation in patient 1 (c.7463A > G, p.Y2488C) is localized in the highly conserved FYRC domain of KMT2B. This mutation holds the potential to alter the inter-domain FYR interactions, which could lead to KMT2B instability. The mutations in patients 2 and 3 (c.3596_3697insC, p.M1202Dfs*22; c.4229delA, p.Q1410Rfs*12) lead to predicted unstable transcripts, likely to be subject to degradation by non-sense-mediated decay. Childhood-onset progressive dystonia with orofacial involvement is one of the main clinical manifestations of KMT2B mutations. In all, 26% (18/69) of the reported cases have T2 signal alterations of the globus pallidus internus, mostly at a younger age. Anticholinergic medication and GPi-DBS are promising treatment options and shall be considered early.