De novo DHDDS variants cause a neurodevelopmental and neurodegenerative disorder with myoclonus

Subcellular membrane systems are highly enriched in dolichol, whose role in organelle homeostasis and endosomal-lysosomal pathway remains largely unclear besides being involved in protein glycosylation. DHDDS encodes for the catalytic subunit (DHDDS) of the enzyme cis-prenyltransferase (cis-PTase), involved in dolichol biosynthesis and dolichol-dependent protein glycosylation in the endoplasmic reticulum. An autosomal recessive form of retinitis pigmentosa (retinitis pigmentosa 59) has been associated with a recurrent DHDDS variant. Moreover, two recurring de novo substitutions were detected in a few cases presenting with neurodevelopmental disorder, epilepsy, and movement disorder. We evaluated a large cohort of patients (n=25) with de novo pathogenic variants in DHDDS and provided the first systematic description of the clinical features and long-term outcome of this new neurodevelopmental and neurodegenerative disorder. The functional impact of the identified variants was explored by yeast complementation system and enzymatic assay. Patients presented during infancy or childhood with a variable association of neurodevelopmental disorder, generalized epilepsy, action myoclonus/cortical tremor, and ataxia. Later in the disease course they experienced a slow neurological decline with the emergence of hyperkinetic and/or hypokinetic movement disorder, cognitive deterioration, and psychiatric disturbances. Storage of lipidic material and altered lysosomes were detected in myelinated fibers and fibroblasts, suggesting a dysfunction of the lysosomal enzymatic scavenger machinery. Serum glycoprotein hypoglycosylation was not detected and, in contrast to retinitis pigmentosa and other congenital disorders of glycosylation involving dolichol metabolism, the urinary dolichol D18/D19 ratio was normal. Mapping the disease-causing variants into the protein structure revealed that most of them clustered around the active site of the DHDDS subunit. Functional studies using yeast complementation assay and in vitro activity measurements confirmed that these changes affected the catalytic activity of the cis-PTase and showed growth defect in yeast complementation system as compared with the wild-type enzyme and retinitis pigmentosa-associated protein. In conclusion, we characterized a distinctive neurodegenerative disorder due to de novo DHDDS variants, which clinically belongs to the spectrum of genetic progressive encephalopathies with myoclonus. Clinical and biochemical data from this cohort depicted a condition at the intersection of congenital disorders of glycosylation and inherited storage diseases with several features akin to of progressive myoclonus epilepsy such as neuronal ceroid lipofuscinosis and other lysosomal disorders

CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/− mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/− mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/− mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/− brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.CAG was supported by the Eunice Kennedy Shriver National Institute Of Child Health & Human Development of the National Institutes of Health under Award Number P50 HD103525. This work was funded by PID2020-112831GB-I00 AEI /10.13039/501100011033 (MN). SS was supported by a grant from the NIH/NINDS (K23NS119666). SWS is supported by the Hospital for Sick Children Foundation, Autism Speaks, and the University of Toronto McLaughlin Center. EM-G was supported by a grant from MICIU FPU18/06240. EVS. was supported by a grant from the NIH (EY025718). CRF was supported by the fund to support clinical research careers in the Region of Southern Denmark (Region Syddanmarks pulje for kliniske forskerkarriereforløb).Peer reviewe

Natural history of KBG syndrome in a large European cohort

KBG syndrome (KBGS) is characterized by distinctive facial gestalt, short stature and variable clinical findings. With ageing, some features become more recognizable, allowing a differential diagnosis. We aimed to better characterize natural history of KBGS. In the context of a European collaborative study, we collected the largest cohort of KBGS patients (49). A combined array- based Comparative Genomic Hybridization and next generation sequencing (NGS) approach investigated both genomic Copy Number Variants and SNVs. Intellectual disability (ID) (82%) ranged from mild to moderate with severe ID identified in two patients. Epilepsy was present in 26.5%. Short stature was consistent over time, while occipitofrontal circumference (median value: -0.88 SD at birth) normalized over years. Cerebral anomalies, were identified in 56% of patients and thus represented the second most relevant clinical feature reinforcing clinical suspicion in the paediatric age when short stature and vertebral/dental anomalies are vague. Macrodontia, oligodontia and dental agenesis (53%) were almost as frequent as skeletal anomalies, such as brachydactyly, short fifth finger, fifth finger clinodactyly, pectus excavatum/carinatum, delayed bone age. In 28.5% of individuals, prenatal ultrasound anomalies were reported. Except for three splicing variants, leading to a premature termination, variants were almost all frameshift. Our results, broadening the spectrum of KBGS phenotype progression, provide useful tools to facilitate differential diagnosis and improve clinical management. We suggest to consider a wider range of dental anomalies before excluding diagnosis and to perform a careful odontoiatric/ear-nose-throat (ENT) evaluation in order to look for even submucosal palate cleft given the high percentage of palate abnormalities. NGS approaches, following evidence of antenatal ultrasound anomalies, should include ANKRD11.</p

Differentiell exprimierte Gene in Neurofibromatose Typ 1 assoziierten gutartigen und bösartigen Nervenscheidentumoren

Neurofibromatosis type 1 (NF1) is one of the most frequent dominantly inherited diseases. The incidence is about 1:3,500 newborn. NF1 patients harbour an increased risk of developing benign nerve sheath tumours such as dermal neurofibromas (dNFs) and plexiform neurofibromas (pNFs) and a 10% lifetime risk of developing malignant peripheral nerve sheath tumours (MPNST). MPNST that usually arise from pre-existing pNFs are highly aggressive malignancies and have a dismal prognosis. To identify genes involved in NF1-tumourigenesis we performed gene expression analysis applying cDNA array technology. 26 NF1-associated tumours and 2 MPNST cell cultures were examined. Using immunohistochemistry and/or Western blotting, 8 genes were evaluated on the protein level. Thus, TP53 gene status was screened by single strand conformational polymorphism in 36 MPNST patients. Expression of 57 genes differed significantly between dNFs, pNFs and MPNST. MMP-13, p53, Syn-1 and PDGFR-α were confirmed on the protein level to be overexpressed in MPNST while Syn-4, PrP and ApoD showed increased expression in neurofibromas. MMP-13 expression was significantly associated with p53 accumulation and with a higher risk of relapse in MPNST patients. TP53 mutants were observed in 11% of MPNST patients. Polymorphism TP53Pro72 was associated with the development of metastases. A panel of genes useful for subclassification of nerve sheath tumours was identified by expression analysis. NF1-associated and sporadic MPNST could not be distinguished by this approach. MMP-13, a matrix metalloproteinase involved in tumour invasion and dissemination, was reported to be stimulated by certain TP53 mutants. The observation that most MMP-13 positive MPNST carried wild-type TP53 suggests the existence of other regulation mechanisms. Nevertheless, MMP-13 expression might be considered a risk factor for relapse. This doctoral thesis has identified several proteins likely to be involved in NF-1 tumourigenesis. The existence of medicines that inhibit MMP-13 and PDGFR-α expression might help to improve therapy for MPNST patients.Die Neurofibromatose Typ 1 (NF1) ist eine der häufigsten dominant vererbten Erkrankungen. Die Inzidenz liegt bei 1:3.500 Neugeborenen. Patienten mit NF1 haben ein erhöhtes Risiko gutartige Nervenscheidentumore wie dermale Neurofibrome (dNFs) und plexiforme Neurofibrome (pNFs) zu entwickeln und ein 10%iges Risiko im Laufe ihres Lebens an einem malignen peripheren Nervenscheidentumor (MPNST) zu erkranken. MPNST, die in der Regel aus pNFs hervorgehen, sind sehr aggressiv und haben eine schlechten Prognose. Um Gene zu identifizieren, die eine Rolle bei der NF1-assoziierten Tumorgenese spielen, wurde eine Genexpressionsanalyse mittels cDNA-Array Technologie durchgeführt. 26 NF1-assoziierte Tumore und 2 MPNST Zelllinien wurden untersucht. 8 Gene wurden auf Proteinebene mittels Immunhistochemie und/ oder Western blot untersucht. Insgesamt wurden Tumore von 56 NF1 Patienten analysiert. Außerdem wurde das TP53 Gen mittels single strand conformational polymorphism (SSCP) auf Mutationen untersucht. Siebenundfünfzig Gene zeigten signifikante Expressionsunterschiede zwischen dNF, pNF und MPNST. Auf Proteinebene konnte eine stärkere Expression von MMP-13, p53, Syn-1 und PDGFR-α in MPNST nachgewiesen werden. Syn-4, PrP und ApoD zeigten erhöhte Expression in Neurofibromen. MMP-13 Expression korrelierte mit p53 Ablagerung und einem erhöhtem Rezidivrisiko. TP53 Mutanten wurde nur in 11% der MPNST detektiert. Die p53Pro72 Variante zeigte eine Assoziation mit Metastasierung. Die Studie identifizierte eine Serie von Genen, die bei der Subklassifizierung von Nervenscheidentumoren hilfreich sein können. NF1-assoziierte und sporadische MPNST konnten nicht differenziert werden. Frühere Studien zeigten, dass die Matrixmetalloproteinase MMP-13, welche eine Rolle bei Invasion und Metastasierung spielt, durch p53 Mutanten stimuliert wird. Die Beobachtung, dass die Mehrheit der hier untersuchten MMP-13-positiven Tumore wildtyp TP53 trugen, weißt auf andere Regulationsmechanismen. MMP-13 könnte sich allerdings als prognostischer Marker eignen. Diese Doktorarbeit hat Proteine identifiziert, die mutmaßlich eine Rolle bei Entwicklung von Nervenscheidentumoren spielen. Bereits vorhandene Medikamente, die MMP-13 und PDGFR-α inhibieren, könnten zu verbesserter Behandlung von MPNST Patienten beitragen

Blunted circadian variation of blood pressure in individuals with neurofibromatosis type 1

Abstract Background Cardiovascular events such as myocardial infarction and stroke are life-threatening complications associated with Neurofibromatosis type 1 (NF1). As previous studies observed an association between cardiovascular events and the loss of circadian variations of blood pressure, we investigated the 24 h circadian rhythm of blood pressure (BP) in 24 NF1 patients (10 males and 14 females, with a mean age of 39.5 years ± 14 years) by using ambulatory blood pressure monitoring (ABPM). Results Only one-third of the patient were dippers, 50% were non-dippers, and 17% were risers. Reduced variability of systolic and diastolic nocturnal blood pressure was observed in NF1 patients compared with several studies of normotensive individuals (p = 0.024). In NF1 patients, the blunted systolic nocturnal decline was significantly associated with the number of neurofibromas (p = 0.049) and the presence of a plexiform neurofibroma (p = 0.020). Conclusions Most NF1 patients in this study showed a “non-dipper” pattern with a blunted nocturnal BP decline, which is considered an independent risk factor for cardiovascular events in normotensive and hypertensive individuals. Periodic monitoring of BP should be included in NF1 follow-up guidelines to diagnose masked hypertension or a non-dipper/riser pattern which would significantly increase the morbidity and mortality of NF1 patients to implement therapeutic strategies

Additional file 1 of Impact of neurofibromatosis type 1 on quality of life using the Skindex-29 questionnaire quality of life in NF1

Supplementary Material

MMP-13, p53 in the Progression of Malignant Peripheral Nerve Sheath Tumors

Malignant peripheral nerve sheath tumors (MPNST) are sarcomas with poor prognosis, limited treatment options. Factors contributing to tumor progression are largely unknown. We therefore examined MPNST from 22 neurofibromatosis type 1 (NF1) patients, 14 nonNF1 patients, 14 neurofibroma patients for matrix metalloproteinase 13 (MMP-13) expression. Because wild-type, mutant p53 were shown to differentially regulate MMP-13 expression, TP53 status, protein levels were also determined. MMP-13 expression was detected in 58% of MPNST, was significantly associated with recurrent MPNST (P = .019). p53 was observed in 78% of MPNST, was found to be strongly associated with MMP-13 expression (P = .005). In contrast, 14 neurofibromas lacked MMP-13, p53 expressions. TP53 mutations were found in only 11% of MPNST, were associated with high tumor grades (P = .029). No significant association between mutant TP53, MMP-13 was observed, indicating that other factors drive MMP-13 expression in MPNST. The presence of metastasis was linked to p53Pro72 polymorphism (P= .041), shorter survival. In summary, our data suggest that MMP-13 expression in nerve sheath tumors is coupled with malignant progression. Therefore, MMP-13 may serve as a marker for progression, as a therapeutic target

Further delineation of the rare GDACCF (global developmental delay, absent or hypoplastic corpus callosum, dysmorphic facies syndrome): genotype and phenotype of 22 patients with ZNF148 mutations.

BACKGROUND Pathogenic variants in the zinc finger protein coding genes are rare causes of intellectual disability and congenital malformations. Mutations in the ZNF148 gene causing GDACCF syndrome (global developmental delay, absent or hypoplastic corpus callosum, dysmorphic facies; MIM #617260) have been reported in five individuals so far. METHODS As a result of an international collaboration using GeneMatcher Phenome Central Repository and personal communications, here we describe the clinical and molecular genetic characteristics of 22 previously unreported individuals. RESULTS The core clinical phenotype is characterised by developmental delay particularly in the domain of speech development, postnatal growth retardation, microcephaly and facial dysmorphism. Corpus callosum abnormalities appear less frequently than suggested by previous observations. The identified mutations concerned nonsense or frameshift variants that were mainly located in the last exon of the ZNF148 gene. Heterozygous deletion including the entire ZNF148 gene was found in only one case. Most mutations occurred de novo, but were inherited from an affected parent in two families. CONCLUSION The GDACCF syndrome is clinically diverse, and a genotype-first approach, that is, exome sequencing is recommended for establishing a genetic diagnosis rather than a phenotype-first approach. However, the syndrome may be suspected based on some recurrent, recognisable features. Corpus callosum anomalies were not as constant as previously suggested, we therefore recommend to replace the term 'GDACCF syndrome' with 'ZNF148-related neurodevelopmental disorder'