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Mitochondrial diseases are genetic disorders impairing mitochondrial functions. Here we describe a patient with a neurodegenerative condition associated with myopia, bilateral sensorineural hearing loss and motor disorders. Brain MRIs showed major cortico-subcortical and infra-tentorial atrophies, as well as intracerebral iron accumulation and central calcifications, compatible with a NBIA-like phenotype. Mitochondrial DNA analysis revealed an undescribed variant: m.8091G>A in the MT-CO2 gene, associated with a complex IV deficiency and a decrease of the mitochondrial respiratory chain capabilities. We report here this pathogenic variant, associated with a NBIA-like phenotype., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Purpose: CAG/CAA repeat expansions in TBP >49 are responsible for spinocerebellar ataxia (SCA) type 17 (SCA17). We previously detected cosegregation of STUB1 variants causing SCA48 with intermediate alleles of TBP in 2 families. This cosegregation questions the existence of SCA48 as a monogenic disease., Methods: We systematically sequenced TBP repeats in 34 probands of dominant ataxia families with STUB1 variants. In addition, we searched for pathogenic STUB1 variants in probands with expanded alleles of TBP >49 (n = 2) or intermediate alleles of TBP ≥40 (n = 47)., Results: STUB1 variants were found in half of the TBP 40-49 cohort. Mirroring this finding, TBP 40-49 alleles were detected in 40% of STUB1 probands. The longer the TBP repeat length, the more likely the occurrence of cognitive impairment (P = .0129) and the faster the disease progression until death (P = .0003). Importantly, 13 STUB1 probands presenting with the full SCA48 clinical phenotype had normal TBP 37-39 alleles, excluding digenic inheritance as the sole mode., Conclusion: We show that intermediate TBP 40-49 alleles act as disease modifiers of SCA48 rather than a STUB1/TBP digenic model. This distinction from what has been proposed before has crucial consequences for genetic counseling in SCA48., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2022 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.)

Purpose: Diagnosis of inherited ataxia and related diseases represents a real challenge given the tremendous heterogeneity and clinical overlap of the various causes. We evaluated the efficacy of molecular diagnosis of these diseases by sequencing a large cohort of undiagnosed families., Methods: We analyzed 366 unrelated consecutive patients with undiagnosed ataxia or related disorders by clinical exome-capture sequencing. In silico analysis was performed with an in-house pipeline that combines variant ranking and copy-number variant (CNV) searches. Variants were interpreted according to American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines., Results: We established the molecular diagnosis in 46% of the cases. We identified 35 mildly affected patients with causative variants in genes that are classically associated with severe presentations. These cases were explained by the occurrence of hypomorphic variants, but also rarely suspected mechanisms such as C-terminal truncations and translation reinitiation., Conclusion: A significant fraction of the clinical heterogeneity and phenotypic overlap is explained by hypomorphic variants that are difficult to identify and not readily predicted. The hypomorphic C-terminal truncation and translation reinitiation mechanisms that we identified may only apply to few genes, as it relies on specific domain organization and alterations. We identified PEX10 and FASTKD2 as candidates for translation reinitiation accounting for mild disease presentation., (© 2021. The Author(s), under exclusive licence to the American College of Medical Genetics and Genomics.)

Purpose: Pathogenic variants in STUB1 were initially described in autosomal recessive spinocerebellar ataxia type 16 and dominant cerebellar ataxia with cerebellar cognitive dysfunction (SCA48)., Methods: We analyzed a large series of 440 index cerebellar ataxia cases, mostly with dominant inheritance., Results: STUB1 variants were detected in 50 patients. Age at onset and severity were remarkably variable. Cognitive impairment, predominantly frontal syndrome, was observed in 54% of STUB1 variant carriers, including five families with Huntington or frontotemporal dementia disease-like phenotypes associated with ataxia, while no STUB1 variant was found in 115 patients with frontotemporal dementia. We report neuropathological findings of a STUB1 heterozygous patient, showing massive loss of Purkinje cells in the vermis and major loss in the cerebellar hemispheres without atrophy of the pons, hippocampus, or cerebral cortex. This screening of STUB1 variants revealed new features: (1) the majority of patients were women (70%) and (2) "second hits" in AFG3L2, PRKCG, and TBP were detected in three families suggesting synergic effects., Conclusion: Our results reveal an unexpectedly frequent (7%) implication of STUB1 among dominantly inherited cerebellar ataxias, and suggest that the penetrance of STUB1 variants could be modulated by other factors, including sex and variants in other ataxia-related genes.

Schwannomatosis is a rare affection predisposing to multiple peripheral neurologic tumors development. Approximatively, one third of patients with schwannomatosis are carriers of a germline mutation in LZTR1 (Leucin Zipper Transcription Regulator 1). Tumorigenesis in schwannomatosis responds to a somatic 5-hit/3-step mechanism resulting in a loss of function (LOF) of LZTR1 and the contiguous genes of locus 22q11.2q12.2. Effectively, LZTR1 is mapped on 22q11.2 and centromeric to SMARCB1 also implicated in the determinism of schwannomatosis and NF2, responsible for neurofibromatosis type 2. On a somatic point of view, LZTR1 mutations are known to drive with a significant frequency glioblastoma (GB) development. We report here two families in which segregate both multiple schwannomas and GB. In the first family, the proband received a diagnosis with of schwannomatosis after a surgery for a lumbar schwannoma at age 43, molecularly confirmed by identification of a germline heterozygous mutation in LZTR1. Her father, having unremarkable medical history deceased from an apparently isolated GB at age 59. In the second family, LZTR1-related schwannomatosis was diagnosed in the index case at age 70 after multiple schwannomas surgeries. Her elder sister had no neurological medical history before occurrence of a lethal GB at age 78. Molecular analysis of GB sample from both affected relatives showed the presence of the familial mutation. These observations hypothesize a potential link between schwannomatosis and the GB development., (Published by Elsevier Masson SAS.)

The CACNA1A gene encodes a calcium-dependent voltage channel, localized in neuronal cells. Pathogenic variants in this gene are known to lead to a broad clinical spectrum including episodic ataxia type 2, spinocerebellar ataxia type 6, familial hemiplegic migraine, and more recently epileptic encephalopathy. We report a large family revealing a wide variability of neurological manifestations associated with a CACNA1A missense pathogenic variant. The index case had early-onset epileptic encephalopathy with progressive cerebellar atrophy, although his mother and his great-grandmother suffered from paroxystic episodic ataxia. His grandfather and great grand-aunt reported no symptoms, but two of her sons displayed early-onset ataxia with intellectual disability. Two of her little daughters suffered from gait disorders, and also from epilepsy for one of them. All these relatives were carriers of the previously described heterozygous variant in CACNA1A gene. We report here the first family leading to major clinical variability and incomplete penetrance. Our family highlights the difficulties to provide accurate genetic counselling concerning prenatal diagnosis regarding highly variable severity of the clinical presentation., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Filamin A (FLNa) links the cell membrane with the cytoskeleton and is central in several cellular processes. Heterozygous mutations in the X-linked FLNA gene are associated with a large spectrum of conditions, including macrothrombocytopenia, called filaminopathies. Using an isogenic pluripotent stem cell model derived from patients, we show that the absence of the FLNa protein in megakaryocytes (MKs) leads to their incomplete maturation, particularly the inability to produce proplatelets. Reduction in proplatelet formation potential is associated with a defect in actomyosin contractility, which results from inappropriate RhoA activation. This dysregulated RhoA activation was observed when MKs were plated on fibrinogen but not on other matrices (fibronectin, vitronectin, collagen 1, and von Willebrand factor), strongly suggesting a role for FLNa/α IIb β 3 interaction in the downregulation of RhoA activity. This was confirmed by experiments based on the overexpression of FLNa mutants deleted in the α IIb β 3 -binding domain and the RhoA-interacting domain, respectively. Finally, pharmacological inhibition of the RhoA-associated kinase ROCK1/2 restored a normal phenotype and proplatelet formation. Overall, this work suggests a new etiology for macrothrombocytopenia, in which increased RhoA activity is associated with disrupted FLNa/α IIb β 3 interaction., (© 2019 by The American Society of Hematology.)

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of the motor pathways, invariably leading to death within a few years of onset. Most cases of ALS are sporadic, but familial forms of the disease (FALS) constitute 10% of the cases. Since the first identification of a causative gene in the 1990s and with recent advances in genetics, more than twenty genes have now been linked to FALS. This increased number of genes led to a tremendous amount of research, clearly contributed to a better understanding of the pathophysiology of this disorder, and paved the way for the development of new therapeutics and new hope for this fatal disease., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Purpose: To investigate the genetic basis of congenital ataxias (CAs), a unique group of cerebellar ataxias with a nonprogressive course, in 20 patients from consanguineous families, and to identify new CA genes., Methods: Singleton -exome sequencing on these 20 well-clinically characterized CA patients. We first checked for rare homozygous pathogenic variants, then, for variants from a list of genes known to be associated with CA or very early-onset ataxia, regardless of their mode of inheritance. Our replication cohort of 180 CA patients was used to validate the new CA genes., Results: We identified a causal gene in 16/20 families: six known CA genes (7 patients); four genes previously implicated in another neurological phenotype (7 patients); two new candidate genes (2 patients). Despite the consanguinity, 4/20 patients harbored a heterozygous de novo pathogenic variant., Conclusion: Singleton exome sequencing in 20 consanguineous CA families led to molecular diagnosis in 80% of cases. This study confirms the genetic heterogeneity of CA and identifies two new candidate genes (PIGS and SKOR2). Our work illustrates the diversity of the pathophysiological pathways in CA, and highlights the pathogenic link between some CA and early infantile epileptic encephalopathies related to the same genes (STXBP1, BRAT1, CACNA1A and CACNA2D2).

Myopathies and muscular dystrophies (M-MDs) are genetically heterogeneous diseases, with >100 identified genes, including the giant and complex titin (TTN) and nebulin (NEB) genes. Next-generation sequencing technology revolutionized M-MD diagnosis and revealed high frequency of TTN and NEB variants. We developed a next-generation sequencing diagnostic strategy targeted to the coding sequences of 135 M-MD genes. Comparison of two targeted capture technologies (SeqCap EZ Choice library capture kit and Nextera Rapid Capture Custom Enrichment kit) and of two whole-exome sequencing kits (SureSelect V5 and TruSeq RapidExome capture) revealed best coverage with the SeqCap EZ Choice protocol. A marked decrease in coverage was observed with the other kits, affecting mostly the first exons of genes and the repeated regions of TTN and NEB. Bioinformatics analysis strategy was fine-tuned to achieve optimal detection of variants, including small insertions/deletions (INDELs) and copy number variants (CNVs). Analysis of a cohort of 128 patients allowed the detection of 52 substitutions, 13 INDELs (including a trinucleotide repeat expansion), and 3 CNVs. Two INDELs were localized in the repeated regions of NEB, suggesting that these mutations may be frequent but underestimated. A large deletion was also identified in TTN that is, to our knowledge, the first published CNV in this gene., (Copyright © 2018 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

Non-specific gastrointestinal symptoms, including pain, diarrhoea, nausea, and vomiting, can be the first symptoms of Fabry disease. They may suggest more common disorders, e.g. irritable bowel syndrome or inflammatory bowel disease. The confounding clinical presentation and rarity of Fabry disease often cause long diagnostic delays and multiple misdiagnoses. Therefore, specialists involved in the clinical evaluation of non-specific upper and lower gastrointestinal symptoms should recognize Fabry disease as a possible cause of the symptoms, and should consider Fabry disease as a possible differential diagnosis. When symptoms or family history suggest Fabry disease, in men, low alpha-galactosidase A enzyme levels, and in women, specific Fabry mutations confirm the diagnosis. In addition to symptomatic treatments, disease-specific enzyme replacement therapy with recombinant human alpha-galactosidase A enzyme or chaperone therapy (migalastat) in patients with amenable mutations can improve the disease, including gastrointestinal symptoms, and should be initiated as early as possible after Fabry disease has been confirmed; starting enzyme replacement therapy at as young an age as possible after diagnosis improves long-term clinical outcomes. Improved diagnostic tools, such as a modified gastrointestinal symptom rating scale, may facilitate diagnosing Fabry disease in patients with gastrointestinal symptoms of unknown cause and thus assure timely initiation of disease-specific treatment., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The wide spectrum of hereditary muscular disorders leads to unavoidable difficulties in their classification, even for specialists. For this reason, new proposals are required that would ultimately replace our current rather complex classifications by a simpler structure. Our proposal will be limited to dystrophic and non-dystrophic myopathies (excluding metabolic disorders, mitochondriopathies, and channelopathies) for which similar proposals would also be relevant. Various genes (encoding structural proteins associated with the sarcolemma, nuclear membrane proteins, and proteins involved in myofiber metabolism have now been sequenced and mutations ascribed to specific forms of inherited muscular disorders. Based on our observations and our recent proposals in other neurogenetic conditions and informal discussions with specialists of neuromuscular disorders, the prerequisite for a simple and sound classification for inherited muscular disorders should encompass the clinical and pathological phenotypes (described in a simple and clear manner), the mode of inheritance, and the mutated gene. We think that the denomination of the different subtypes could be simplified considerably, although any new proposal of classification of muscular disorders will need to be discussed in the neurological and genetic communities., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Purpose: Treacher Collins/Franceschetti syndrome (TCS; OMIM 154500) is a disorder of craniofacial development belonging to the heterogeneous group of mandibulofacial dysostoses. TCS is classically characterized by bilateral mandibular and malar hypoplasia, downward-slanting palpebral fissures, and microtia. To date, three genes have been identified in TCS:,TCOF1, POLR1D, and POLR1C., Methods: We report a clinical and extensive molecular study, including TCOF1, POLR1D, POLR1C, and EFTUD2 genes, in a series of 146 patients with TCS. Phenotype-genotype correlations were investigated for 19 clinical features, between TCOF1 and POLR1D, and the type of mutation or its localization in the TCOF1 gene., Results: We identified 92/146 patients (63%) with a molecular anomaly within TCOF1, 9/146 (6%) within POLR1D, and none within POLR1C. Among the atypical negative patients (with intellectual disability and/or microcephaly), we identified four patients carrying a mutation in EFTUD2 and two patients with 5q32 deletion encompassing TCOF1 and CAMK2A in particular. Congenital cardiac defects occurred more frequently among patients with TCOF1 mutation (7/92, 8%) than reported in the literature., Conclusion: Even though TCOF1 and POLR1D were associated with extreme clinical variability, we found no phenotype-genotype correlation. In cases with a typical phenotype of TCS, 6/146 (4%) remained with an unidentified molecular defect.

Neurofibromatosis type 1 (NF1) is an autosomal dominant, multi-system, neurocutaneous disorder that predisposes to the development of benign and malignant tumors with a birth incidence rate of 1 in 2500-3000. 50% of cases are sporadic. The diagnosis is exclusively based on clinical assessment with clinical diagnostic criteria such as café-au-lait spots, neurofibromas, axillary or groin freckling, Lisch nodules, optic pathway glioma, bony dysplasia and first-degree relative with NF1. We report a family with NF1 in which two members presented atypical clinical features in addition to the classical diagnostic criteria. Three relatives affected by NF1, a father and two of his three sons, are described. The clinical diagnosis was originally worn in all three cases, with the association many spots café-au -lait over the entire body and some axillary freckling as well as first-degree relative. One case presented an Acute Myeloid Leukemia (AML) type 2 at 10 years of age diagnosed before the revelation of bicytopenia associated pallor and isolated asthenia. A second case presented a nephrotic syndrome at 4 years of age due to the association of hydrops with headache and asthenia. Direct sequencing of NF1 led to identify the familial mutation, a previously unreported heterozygous missense mutation c.3443C > A, p.Ala1148Glu in exon 20 which segregated with all three affected patients. The family described in this report confirms the high clinical variability of NF1, even intrafamilial, and raises the question as to whether rare features such as AML and nephrotic syndrome are associated with NF1. Some NF1 patients presenting glomerular diseases or AML have rarely been reported, but due to the small number of cases described the mechanisms underlying these associations are poorly understood. However, it seems important to be aware of the possible occurrence of nephritic syndrome and/or malignant blood diseases in NF1 patients., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Periventricular nodular heterotopia, the most common form of cortical malformation in adulthood, is characterized by nodules of neurons ectopically placed along the lateral ventricles. Classically, ectopic nodules are bilateral and symmetric defining bilateral periventricular nodular heterotopia (BPNH). BPNH can lead to epilepsy and intellectual disability of variable severity. The X-linked dominant form of BPNH, related to mutations in FLNA encoding filamin A, is the major cause of BPNH, causing prenatal and neonatal lethality in males that explain the excess of affected women. However, few living males have been described with this condition. In addition, mutations in FLNA have been also exceptionally associated with unilateral nodular heterotopia. We describe here three new patients, all carrying a novel missense mutation in FLNA. Two of the patients were adult males with BPNH; both had normal cognitive development and one did not manifest any seizure until he died at age 57. The last patient was a female adult with epilepsy and focal nodules essentially located along the right ventricle. We compare the clinical and imaging data of our patients with those of previously described similar cases. The type and location of FLNA mutations leading to such atypical presentations are discussed., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

We report a 19 year-old patient carrying a terminal 20p microdeletion. She displayed clinical features resembling those of two other previously described patients. We suggest that a specific phenotype can be associated with this chromosomal anomaly. Mental retardation, epilepsy, and dysmorphic signs including low-set ears and overfolded helices seem highly characteristic of this syndrome and may define major diagnostic criteria of a recognizable phenotype. Delayed closure of fontanella, delayed permanent teeth eruption, visual disturbances, prominent ear lobes, prominent nasal root and ridge, thin upper lip and brachydactyly may represent inconstant minor criteria., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

We report on a boy presenting with features of OAVS (Oculoauriculovertebral spectrum) and carrying a 1.5 Mb microdeletion in 15q24.1q24.2. This recurrent deletion usually leads to a broad clinical spectrum but has never been found associated with features of OAVS such as ear agenesis. This observation is in accordance with OAVS being a genetically heterogeneous disorder, and points out the importance of array-CGH screening in this disorder., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Filaminopathies A caused by mutations in the X-linked FLNA gene are responsible for a wide spectrum of rare diseases including 2 main phenotypes, the X-linked dominant form of periventricular nodular heterotopia (FLNA-PVNH) and the otopalatodigital syndrome spectrum of disorders. In platelets, filamin A (FLNa) tethers the principal receptors ensuring the platelet-vessel wall interaction, glycoprotein Ibα and integrin αIIbβ3, to the underlying cytoskeleton. Hemorrhage, coagulopathy, and thrombocytopenia are mentioned in several reports on patients with FLNA-PVNH. Abnormal platelet morphology in 2 patients with FLNA-PVNH prompted us to examine a third patient with similar platelet morphology previously diagnosed with immunologic thrombocytopenic purpura. Her enlarged platelets showed signs of FLNa degradation in Western blotting, and a heterozygous missense mutation in FLNA was detected. An irregular distribution of FLNa within the total platelet population was shown by confocal microscopy for all 3 patients. In vitro megakaryocyte cultures showed an abnormal differentiation, including an irregular distribution of FLNa with a frayed aspect, the presence of enlarged α-granules, and an abnormal fragmentation of the cytoplasm. Mutations in FLNA may represent an unrecognized cause of macrothrombocytopenia with an altered platelet production and a modified platelet-vessel wall interaction.

Sparse scalp hair, a peculiar shape of the nose, and cone-shaped epiphyses of the phalanges are the hallmarks of the tricho-rhino-phalangeal syndromes (TRPS). Short stature, hip dysplasia, and malformations of inner organs including mitral valve prolpase have also often been described for these conditions. Here, we described a 64-year-old woman with molecularly proved TRPS I and several atypical late-onset rheumatologic and neurological symptoms., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

X-linked periventricular nodular heterotopia (PH) is a neuronal migration disorder caused by mutations in the gene encoding filamin A (FLNA). High phenotypic diversity, ranging from PH to otopalatodigital syndrome and frontometaphyseal dysplasia has been described in association with FLNA mutations. Extra-neurological features including cardiovascular abnormalities, coagulopathy, skeletal dysplasia and joint hypermobility have sometimes been described in patients with PH. Respiratory manifestations have not been associated with FLNA disorders with the exception of tracheal stenosis and pulmonary hypoplasia associated with frontometaphyseal dysplasia and Melnick-Needles syndrome. Here, we report on a male patient aged 6 years presenting with a mosaic nonsense mutation c.994delG within the FLNA gene, PH and severe congenital lung disease comprising bilateral atelectasis, lung cysts, tracheobronchomalacia, pulmonary arterial hypertension and long-term oxygen dependence; histology of resected lung showed panpulmonary emphysema with marked reduction of bronchial cartilage. Rare male patients with PH and FLNA mutations have already been reported, usually with early lethality. These observations suggest the possibility of a link between FLNA mutations and congenital lung disease. A prospective study of patients with PH and FLNA mutations would be helpful in order to test this hypothesis., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Vanishing white matter (VWM) disease, also known as childhood ataxia with central nervous system hypomyelination (CACH) syndrome, is an autosomal recessive transmitted leukodystrophy. Classically characterised by early childhood onset, adult onset formed with slower progression have been recently recognized. The course of neurological impairment is usually progressive with possible occasional episodes of acute deterioration following febrile illnesses or head trauma. Neurological features are dominated by cerebellar ataxia and spasticity with relatively preserved mental abilities. Brain MRI shows diffuse abnormal signal of the cerebral white matter and cystic degeneration. Mutations in one of the genes coding for the five subunits of the translation factor eukaryotic initiation factor 2B (eIF2B) have been identified. We report here on two sisters affected by adult onset VWM with variable phenotypic expression. The proband is remarkable by the very late age of the disease onset (age of 42). A homozygous p.Arg113His mutation in the eIF2Bvarepsilon gene was identified. This mutation had been recurrently associated with adult onset VWM establishing phenotype-genotype correlations. We will show an important intra-familial phenotypic variability and discuss it in the light of recent molecular progresses. External precipitating factors are contributing for some of the differences observed.

The Papillon-Lefèvre syndrome (PLS) is an autosomal recessive disorder. The gene responsible for the disease, cathepsin C (CTSC), is localized in 11q14.1-q14.21. We performed mutational and functional analyses of CTSC in two patients affected by this condition. Three previously unreported CTSC mutations were identified. The first patient had a compound heterozygous status with a p.G386R missense mutation and an intragenic deletion spanning exons 3-7. Second patient carried a homozygous splice site mutation, p.A253SfsX30. CTSC activity was undetectable in both patients, thus demonstrating the pathological effect of these mutations. We describe early evidence of an original intragenic deletion reported in PLS. Since this mutational mechanism could not be detected by direct sequencing, intragenic deletion has to be specifically investigated using gene dosage analysis techniques such as quantitative multiplex fluorescent polymerase chain reaction. We consider that this technique should be performed in patients with apparently homozygous CTSC mutations when one parent does not carry the expected mutation or is not available for analysis.

Purpose: Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder characterized by arteriovenous malformations (AVM), mostly cutaneous and mucous (telangiectases), but also involving the lungs (PAVM), liver (HAVM) and brain (CAVM). We studied the relationship between the phenotype and genotype in patients with a proven mutation in either ENG (HHT1) or ACVRL1 (HHT2)., Methods: Clinical features and their age of onset were compared between HHT1 and HHT2. The type of mutation was also analyzed. Clinical manifestations were distinguished from lesions found by screening., Results: Ninety-three HHT1 patients and 250 HHT2 patients were included. Epistaxis occurred later in HHT2, with incomplete penetrance (P<0.0001). Symptomatic PAVMs were more frequent in HHT1 (34.4 vs. 5.2%, P<0.001), as were cerebral abscesses (7.5 vs. 0.8%, P=0.002). Gastrointestinal bleeding occurred more frequently in HHT2 (16.4 vs. 6.5%, P=0.017). Symptomatic hepatic involvement was only seen in HHT2 patients. PAVMs were more frequently detected in asymptomatic HHT1 patients (54 vs. 12.8%, P<0.0001). PAVMs and HAVMs were often family clustered in HHT1 and HHT2, respectively. Truncating mutations were associated with a higher frequency of epistaxis and telangiectasis, in HHT2., Conclusion: This study shows major differences between HHT1 and HHT2 phenotypes, which should be taken into account for future clinical studies.

Progressive encephalopathy with Edema, Hypsarrhythmia, and Optic atrophy (PEHO syndrome) is a rare recessive autosomal neurodegenerative condition essentially described in Finland. The term PEHO-like syndrome has been proposed for patients who share clinical features of PEHO syndrome but lack the cerebellar atrophy, one of its major diagnostic criteria. We describe a patient presenting with hypoxic-ischaemic encephalopathy and PEHO-like syndrome features.