Rare metabolic disease mimicking COL4A1/COL4A2 fetal brain phenotype.

Pathogenic variants of collagen type IV alpha 1 and 2 (COL4A1/COL4A2) genes cause various phenotypic anomalies, including intracerebral hemorrhage and a wide spectrum of developmental anomalies. Only 20% of fetuses referred for COL4A1/COL4A2 molecular screening (fetuses with a suspected intracerebral hemorrhage) carry a pathogenic variant in these genes, raising questions regarding the causative anomaly in the remaining 80% of these fetuses. We examined, following termination of pregnancy or in-utero fetal death, a series of 113 unrelated fetuses referred for COL4A1/COL4A2 molecular screening, in which targeted sequencing was negative. Using exome sequencing data and a gene-based collapsing test, we searched for enrichment of rare qualifying variants in our fetal cohort in comparison to the Genome Aggregation Database (gnomAD) control cohort (n = 71 702). Qualifying variants in pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) were overrepresented in our cohort, reaching genome-wide significance (P = 2.11 × 10-7 ). Heterozygous PDHA1 loss-of-function variants were identified in three female fetuses. Among these three cases, we observed microcephaly, ventriculomegaly, germinolytic pseudocysts, agenesis/dysgenesis of the corpus callosum and white-matter anomalies that initially suggested cerebral hypoxic-ischemic and hemorrhagic lesions. However, a careful a-posteriori reanalysis of imaging and postmortem data showed that the observed lesions were also consistent with those observed in fetuses carrying PDHA1 pathogenic variants, strongly suggesting that these two phenotypes may overlap. Exome sequencing should therefore be performed in fetuses referred for COL4A1/COL4A2 molecular screening which are screen-negative, with particular attention paid to the PDHA1 gene. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

The Genetic Basis of Moyamoya Disease.

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive spontaneous bilateral occlusion of the intracranial internal cerebral arteries (ICA) and their major branches with compensatory capillary collaterals resembling a "puff of smoke" (Japanese: Moyamoya) on cerebral angiography. These pathological alterations of the vessels are called Moyamoya arteriopathy or vasculopathy and a further distinction is made between primary and secondary MMD. Clinical presentation depends on age and population, with hemorrhage and ischemic infarcts in particular leading to severe neurological dysfunction or even death. Although the diagnostic suspicion can be posed by MRA or CTA, cerebral angiography is mandatory for diagnostic confirmation. Since no therapy to limit the stenotic lesions or the development of a collateral network is available, the only treatment established so far is surgical revascularization. The pathophysiology still remains unknown. Due to the early age of onset, familial cases and the variable incidence rate between different ethnic groups, the focus was put on genetic aspects early on. Several genetic risk loci as well as individual risk genes have been reported; however, few of them could be replicated in independent series. Linkage studies revealed linkage to the 17q25 locus. Multiple studies on the association of SNPs and MMD have been conducted, mainly focussing on the endothelium, smooth muscle cells, cytokines and growth factors. A variant of the RNF213 gene was shown to be strongly associated with MMD with a founder effect in the East Asian population. Although it is unknown how mutations in the RNF213 gene, encoding for a ubiquitously expressed 591 kDa cytosolic protein, lead to clinical features of MMD, RNF213 has been confirmed as a susceptibility gene in several studies with a gene dosage-dependent clinical phenotype, allowing preventive screening and possibly the  development of new therapeutic approaches. This review focuses on the genetic basis of primary MMD only.

Prevalence of COL4A1 and COL4A2 mutations in severe fetal multifocal hemorrhagic and/or ischemic cerebral lesions.

OBJECTIVE: To establish the prevalence of COL4A1 and COL4A2 gene mutations in fetuses presenting with a phenotype suggestive of cerebral injury. METHODS: This was a single-center retrospective analysis of all cases of fetal cerebral anomalies suggestive of COL4A1 or COL4A2 gene mutation over the period 2009-2018. Inclusion criteria were: (1) severe and/or multifocal hemorrhagic cerebral lesions; (2) multifocal ischemic-hemorrhagic cerebral lesions. These anomalies could be of different ages and associated with schizencephaly or porencephaly. Between fetuses with and those without a mutation, we compared gestational age at the time of diagnosis, parity and fetal gender. RESULTS: Among the 956 cases of cerebral anomaly diagnosed in our center during the 10-year study period, 18 fetuses were identified for inclusion. A pathogenic COL4A1 gene mutation was found in five of these cases, among which four were de-novo mutations. A variant of unknown significance was found in four fetuses: in the COL4A1 gene in one case and in the COL4A2 gene in three cases. No COL4A1 or COL4A2 mutation was found in the remaining nine fetuses. The median (interquartile range) gestational age at diagnosis was significantly lower in cases with a mutation (24 (22-26) weeks) than in cases without a mutation (32 (29.5-34.5) weeks) (P = 0.03). CONCLUSIONS: A phenotype suggestive of cerebral injury was found in 18 of the 956 (1.9%) cases in our population, in 28% of which there was an associated COL4A1 or COL4A2 mutation. COL4A1 and COL4A2 gene mutations should be sought systematically in cases of severe and/or multifocal hemorrhagic or ischemic-hemorrhagic cerebral lesions, with or without schizencephaly or porencephaly. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

CADASIL: yesterday, today, tomorrow.

BACKGROUND AND PURPOSE: In 2019, the Brain Prize crowned the discovery of CADASIL in the 1990s and research efforts on this archetypal small vessel disease of the brain over 40 years. METHODS AND RESULTS: The hereditary origin of this arteriolopathy was discovered from a first clinical case and detailed observation of the patient's family. Thereafter, the role of causative mutations within the NOTCH3 gene were identified, allowing the development of a genetic test and then of an animal model of the disease. These crucial steps led to the discovery progressively that CADASIL is the most common genetic cerebral small vessel disease, to describing for the first time the natural history of a cerebral ischaemic small vessel disease from silent cerebral tissue lesions up to severe motor disability and dementia at the end stage, to demonstrating the central role of matrix proteins in its pathophysiology and to opening the door to the discovery of several other genes involved in monogenic cerebral small vessel diseases. DISCUSSION: Today, CADASIL is known to every neurologist, but the disease has not yet revealed all its secrets. A lot of effort is still needed to understand the intimate mechanisms of the disease and the most efficient targets or approaches for the development of efficient therapeutics. The history of CADASIL will be further enriched by multiple ongoing research projects worldwide, at clinical and preclinical level, and will continue to enlighten research in the field of cerebral small vessel disorders.

Monogenic cerebral small-vessel diseases: diagnosis and therapy. Consensus recommendations of the European Academy of Neurology.

BACKGROUND AND PURPOSE: Guidelines on monogenic cerebral small-vessel disease (cSVD) diagnosis and management are lacking. Endorsed by the Stroke and Neurogenetics Panels of the European Academy of Neurology, a group of experts has provided recommendations on selected monogenic cSVDs, i.e. cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), autosomal dominant High Temperature Requirement A Serine Peptidase 1 (HTRA1), cathepsin-A-related arteriopathy with strokes and leukoencephalopathy (CARASAL), pontine autosomal dominant microangiopathy and leukoencephalopathy (PADMAL), Fabry disease, mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and type IV collagen (COL4)A1/2. METHODS: We followed the Delphi methodology to provide recommendations on several unanswered questions related to monogenic cSVD, including genetic testing, clinical and neuroradiological diagnosis, and management. RESULTS: We have proposed 'red-flag' features suggestive of a monogenic disease. General principles applying to the management of all cSVDs and specific recommendations for the individual forms of monogenic cSVD were agreed by consensus. CONCLUSIONS: The results provide a framework for clinicians involved in the diagnosis and management of monogenic cSVD. Further multicentre observational and treatment studies are still needed to increase the level of evidence supporting our recommendations.

Leukoencephalopathy with calcifications and cysts (LCC): 5 cases and literature review.

INTRODUCTION: Leukoencephalopathy with calcifications and cysts (LCC) is a rare autosomal recessive cerebral angiomatous-like microangiopathy characterized by diffuse and asymmetric white-matter lesions associated with multiple calcifications and cysts. The disease is caused by SNORD118 mutations. The entire clinical spectrum of LCC is not yet fully determined. MATERIAL AND METHODS: To define the clinical spectrum of LCC, we analyzed data from recently diagnosed cases and from the litterature. Both clinical and imaging features from our five LCC cases harboring compound heterozygous SNORD118 mutations were presented and all cases reported in the litterature reviewed. RESULTS: Ninety-two LCC cases including our five patients were identified. Consanguinity was rare (4%), and 97% of cases were symptomatic. Mean age of first clinical manifestations was 16.1±16.1 years (range 1 month-71 years) and was earlier in men (10.3±14.3 years) than in women (20.2±22.8 years) (P=0.02). The main inaugural symptoms were seizures (36%; mean age at onset: 5.2±9.5 years) and progressive neurological symptoms including ataxia, dystonia and spasticity (26%; 27.8±23.6 years). Intracranial hypertension was less frequently observed (14%), mostly in adults (mean age 31.5±13.2 years). Ischemic or hemorrhagic strokes were inaugural symptoms in two adults (2%). During follow-up, most patients developed progressive extrapyramidal, cerebellar and pyramidal signs (83%), cognitive decline (56%), seizures (37%), intracranial hypertension (30%) or stroke (2%). CONCLUSION: In LCC, the clinical spectrum is largely heterogeneous and the course of the disease appears highly variable in contrast to other hereditary cerebral small vessel diseases.

A novel large deletion in CCM1 gene in a Tunisian family.

Familial CCM is a rare entity associated with the mutation of three genes: CCM1 (KRIT1), CCM2 (MGC4607), and CCM3 (PDCD10). We report here the first description of a Tunisian familial CCMs composed of six members. The father and two daughters were affected and symptomatic. The two other kindred were healthy. Surgical treatment was performed in only one affected patient. Molecular analysis of KRIT1, MGC4607 and PDCD10 genes identified a large KRIT1 deletion of the first ten exons. To the best of our knowledge, this large deletion has never been reported before.

Research Progresses in Understanding the Pathophysiology of Moyamoya Disease.

BACKGROUND: The pathogenesis of moyamoya disease (MMD) is still unknown. The detection of inflammatory molecules such as cytokines, chemokines and growth factors in MMD patients' biological fluids supports the hypothesis that an abnormal angiogenesis is implicated in MMD pathogenesis. However, it is unclear whether these anomalies are the consequences of the disease or rather causal factors as well as these mechanisms remain insufficient to explain the pathophysiology of MMD. The presence of a family history in about 9-15% of Asian patients, the highly variable incidence rate between different ethnic and sex groups and the age of onset support the role of genetic factors in MMD pathogenesis. However, although some genetic loci have been associated with MMD, few of them have been replicated in independent series. Recently, RNF213 gene was shown to be strongly associated with MMD occurrence with a founder effect in East Asian patients. However, the mechanisms leading from RNF213 mutations to MMD clinical features are still unknown. SUMMARY: The research on pathogenic mechanism of MMD is in its infancy. MMD is probably a complex and heterogeneous disorder, including different phenotypes and genotypes, in which more than a single factor is implicated. KEY MESSAGE: Since the diagnosis of MMD is rapidly increasing worldwide, the development of more efficient stratifying risk systems, including both clinical but also biological drivers became imperative to improve our ability of predict prognosis and to develop mechanism-tailored interventions.

Cerebro-retinal microangiopathy with calcifications and cysts due to recessive mutations in the CTC1 gene.

Cerebro-retinal microangiopathy with calcifications and cysts (CRMCC) or Coats plus syndrome is a pleiotropic disorder affecting the eyes, brain, bone and gastrointestinal tract. Its primary pathogenesis involves small vessel obliterative microangiopathy. Recently, autosomal recessively inherited mutations in CTC1 have been reported in CRMCC patients. We herein report an adolescent referred to our hospital following new seizures in a context of an undefined multisystem disorder. Cerebral imaging disclosed asymmetrical leukopathy, intracranial calcifications and cysts. In addition, he presented other typical CRMCC features i.e. a history of intrauterine growth retardation, skeletal demineralization and osteopenia, bilateral exudative vitreo-retinopathy reminiscent of Coats disease, recurrent gastrointestinal hemorrhages secondary to watermelon stomach and variceal bleeding of the esophagus due to idiopathic portal hypertension and telangiectatic and angiodysplasic changes in the small intestine and colon, and anemia due to recurrent bleeding and bone marrow abnormalities. The patient was diagnosed with Coats plus syndrome. CTC1 gene screening confirmed the diagnosis with the identification of heterozygous deleterious mutations. CRMCC due to CTC1 mutations has a broad clinical expressivity. Our case report illustrates the main possible associated phenotypes and their complications, demonstrating the need for a careful etiological search in order to initiate appropriate therapeutic and preventive measures.

Occurrence of multiple Cerebral Cavernous Malformations in a patient with Neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis 1 (NF1) belongs to the autosomal dominant neurocutaneous disorders' group, which mainly includes NF1 and NF2, tuberous sclerosis, von Hippel-Lindau disease and Cerebral Cavernous Malformations (CCMs). NF1 has a major impact on the nervous system, eye, skin, bone or cardiovascular system. Cerebrovascular lesions have been reported in NF1 including aneurysm, pseudoaneurysm, arteriovenous malformations, vascular stenosis or occlusion and Moya moya syndrome. OBJECTIVE: To report a case of an NF1 patient with multiple CCMs. OBSERVATION: A 47-year-old man with café-au-lait skin lesions, countless cutaneous neurofibromas, short stature and scoliosis was admitted for progressive spinal cord compression due to histologically proven neurofibroma. Systematic cerebral MRI screening including gradient echo sequences showed multiple asymptomatic CCMs. Screening of CCM1, CCM2 and CCM3 genes was negative while a deleterious frameshift mutation was identified in NF1 gene. CONCLUSION: While single CCM can occur in NF1 patients following radiation exposure, they are only rarely reported in non-irradiated NF1 brain. Even if it could be a fortuitous association, plausible links and explanations exist. If cerebral MRI can be systematic in NF1 to detect asymptomatic gliomas, used protocols in neuroradiology do not usually include gradient echo sequences, the most sensitive test for CCM detection, leading possibly to failure to detect these vascular lesions. More reports having this combination and further investigations of NF1 families will certainly provide a better understanding of links between these 2 phakomatoses, as recently reported with "multiple meningiomas" phenotype associated with multiple CCMs in patients with CCM3 gene mutations or café-au-lait skin lesions in CCM1 mutation carriers.

Deep intronic KRIT1 mutation in a family with clinically silent multiple cerebral cavernous malformations.

Loss-of-function mutations in CCM1/KRIT1, CCM2/MGC4607 and CCM3/PDCD10 genes are identified in the vast majority of familial cases with multiple cerebral cavernous malformations (CCMs). However, genomic DNA sequencing combined to large rearrangement screening fails to detect a mutation in 5% of those cases. We report a family in which CCM lesions were discovered fortuitously because of the investigation of a developmental delay in a boy. Three members of the family on three generations had typical multiple CCM lesions and no clinical signs related to CCM. No mutation was detected using genomic DNA sequencing and quantitative multiplex PCR of short fluorescent fragments (QMPSF). cDNA sequencing showed a 99-nucleotide insertion between exons 5 and 6 of CCM1, resulting from a mutation located deep into intron 5 (c.262+132_262+133del) that activates a cryptic splice site. This pseudoexon leads to a premature stop codon. These data highly suggest that deep intronic mutations explain part of the incomplete mutation detection rate in CCM patients and underline the importance of analyzing the cDNA to provide comprehensive CCM diagnostic tests. This kind of mutation may be responsible for apparent sporadic presentations due to a reduced penetrance.

Fetal intracerebral hemorrhage and cataract: think COL4A1.

The COL4A1 gene encodes the alpha1 chain of type IV collagen, a crucial component of nearly all basement membranes. Mutations in COL4A1 were first associated with cerebral microangiopathy and familial porencephaly. Recently, several authors have reported mutations in COL4A1 as a Mendelian cause of prenatal onset intracranial hemorrhage (ICH). We report two cases of prenatal ICH associated with cataract and suggest that COL4A1 mutation should be envisaged in fetuses with prenatal ICH, especially in the presence of lens abnormalities at ultrasound examination.

CCM3 Mutations Are Associated with Early-Onset Cerebral Hemorrhage and Multiple Meningiomas.

Mutations of CCM3/PDCD10 cause 10-15% of hereditary cerebral cavernous malformations. The phenotypic characterization of CCM3-mutated patients has been hampered by the limited number of patients harboring a mutation in this gene. This is the first report on molecular and clinical features of a large cohort of CCM3 patients. Molecular screening for point mutations and deletions was used to identify 54 CCM3-mutated index patients. Age at referral and clinical onset, type of inaugural events and presence of extra-axial lesions were investigated in these 54 index patients and 22 of their mutated relatives. Mean age at clinical onset was 23.0 ± 16 years. Clinical onset occurred before 10 years in 26% of the patients, and cerebral hemorrhage was the initial presentation in 72% of these patients. Multiple extra-axial, dural-based lesions were detected in 7 unrelated patients. These lesions proved to be meningiomas in 3 patients who underwent neurosurgery and pathological examination. This 'multiple meningiomas' phenotype is not associated with a specific CCM3 mutation. Hence, CCM3 mutations are associated with a high risk of early-onset cerebral hemorrhage and with the presence of multiple meningiomas.

Natural history of cerebral dot-like cavernomas.

AIM: To elucidate the natural history of dot-like or "black spot" cavernomas. MATERIALS AND METHODS: Data of 18 children with black spot cavernomas were analysed retrospectively. RESULTS: Eleven boys and seven girls presented 187 black spot cavernomas during a mean observation period of 5.5 years. Mean and median age at diagnosis of the 187 cavernomas was 9.6 years. There were 70 de novo black spot cavernomas. Boys presented significantly more cavernomas than girls. There were three KRIT1 mutation carriers and four PDCD 10 mutation carriers. Children with a PDCD 10 mutation presented significantly more lesions than those children with a KRIT1 mutation (mean number of lesions per patient: 23.3 versus 3.3, respectively). There were 10 radiological haemorrhagic events caused by 10 black spot lesions. Two of these events were symptomatic. The haemorrhage rate of black spot cavernomas was 0.7% per lesion-year. CONCLUSIONS: A mean bleeding rate of 0.7% per lesion-year is lower than the overall haemorrhage rates provided in the literature. Nonetheless, black spot cavernomas are not purely benign lesions. Furthermore, genetic mutations may play a role in the natural history of black spot cavernomas.

Presymptomatic genetic testing in CADASIL.

Genetic counselling has been poorly investigated in cerebrovascular diseases. Characteristics, motivations and long-term outcome of presymptomatic tests (PT) in subjects at risk of CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) were investigated at the National Centre for Rare Vascular Diseases of the Brain and/or Retina (CERVCO). Sociodemographic, motivational and psychological variables were collected between 2003 and 2010 for PT applicants. Multidisciplinary consultations (with a geneticist, neurologist and psychologist) were proposed over a 6 month period. When PT showed a deleterious mutation of the NOTCH3 gene, cognitive performances, mood, autonomy and quality of life were also assessed. Over 7 years, only 33 subjects asked for a PT of CADASIL. They were predominantly women, lived as a couple, had children and were of high sociocultural level. The dropout rate after the first step of the procedure was 63%. The characteristics of the 11 subjects who reached the end of the procedure did not differ from the 22 who dropped out. Six were carriers of the deleterious mutation and were still asymptomatic after a mean follow-up of 19 months. They did not experience any particular negative event and all of them indicated a high score of overall quality of life. Indeed, two carriers gave birth to their first child. These initial data in CADASIL show that PT is rarely requested and that there is a high dropout rate. Our study also highlights that a multidisciplinary and multistep procedure in genetic counselling testing appears useful to obtain minimal harmful consequences of genetic testing.

COL4A1 mutations associated with a characteristic pattern of intracranial calcification.

Intracranial calcification (ICC) is a relatively common radiological finding in children undergoing investigation for neurological disorders. Many causes are recognised, and ICC is often regarded as a non-specific sign.From an ongoing study of ICC, we identified 5 patients with characteristic radiological features, in whom a mutation in the COL4A1 gene was found.All patients had CT and MR imaging. MR images demonstrated features of periventricular leukomalacia with irregular dilatation of the lateral ventricles with or without porencephaly, loss of hemispheric white matter volume, and high signal on T2 and FLAIR sequences within periventricular and deep white matter. Calcification was apparent on MR in 4 patients. CT scans demonstrated spot and linear calcification in the subependymal region and around areas of porencephaly. Calcification was also visible in the deep cerebral white matter and basal ganglia. 1 patient showed calcification in the central pons.ICC occurs in COL4A1-related disease. The radiological features are distinct from other conditions demonstrating recognisable patterns of ICC, such as congenital cytomegalovirus infection and Aicardi-Goutiéres syndrome. In the absence of a known risk factor for periventricular leukomalacia, the presence of these radio-logical findings should suggest the possibility of COL4A1-related disease.

[Genetic syndromes that mimic congenital infections: report of 2 cases]. / Syndromes génétiques mimant les infections congénitales : à propos de 2 cas.

Genetic syndromes that mimic congenital infections must be recognized because of the associated risk of recurrence. We describe a male infant who was born with the association of intra-uterine growth retardation, microcephaly, intracranial calcifications, white matter abnormalities, microphtalmy, bilateral cataract, and hearing loss. Congenital cytomegalovirus (CMV) infection was suspected, but serologic CMV markers were not decisive (IgG+/IgM-). His half-sister (same father) presented a similar phenotype. Therefore, the diagnosis of congenital CMV infection was questioned and a genetic hypothesis was suggested. In 1983, Baraitser et al. first described two brothers with microcephaly and intracranial calcifications and negative TORCH analysis. Later, a number of authors reported children in whom detailed investigation failed to objectively confirm an intra-uterine infective agent. Clinical features include severe postnatal microcephaly, seizures, and pronounced developmental arrest. These cases have been considered to define a distinct autosomal recessive disorder first named pseudo-Torch syndrome. The family described herein is different from the cases previously described with a suspected autosomal dominant inheritance, severe ophtalmological abnormalities, and unusual brain imaging.

[Hereditary episodic ataxia]. / Ataxies épisodiques génétiques.

INTRODUCTION: Episodic ataxia (EA) designates a group of autosomal dominant channelopathies that manifest as paroxysmal attacks of imbalance and incoordination. EA conditions are clinically and genetically heterogeneous. Seven types of EA have been reported so far but the majority of clinical cases result from two recognized entities. STATE OF ART: Episodic ataxia type 1 (EA1) is characterized by brief episodes of ataxia and dysarthria, and interictal myokymia. Onset occurs during the first two decades of life. Associated epilepsy has been reported in some EA1 patients. EA1 is caused by mutations of the KCNA1 gene coding for the voltage-gated potassium channel Kv1.1. Mutation is mostly missense mutations. Acetazolamide, a carbonic-anhydrase inhibitor, may reduce the frequency and severity of the attacks in some but not all affected individuals. Episodic ataxia type 2 (EA2) is characterized by episodes lasting longer than in EA1, that manifest by ataxia, dysarthria, vertigo, and also, in most of the cases, an interictal nystagmus. Other clinical features as developmental delay or epilepsy can be present in some patients. Brain MRI shows frequently a vermian atrophy. Onset occurs typically in childhood or early adolescence, but can sometimes be in adulthood. EA2 is caused by mutations in CACNA1A, a gene coding for the neuronal voltage-gated calcium channel Cav1.1. For two-thirds of the cases, mutations lead to a stop codon. This type is most often responsive to acetazolamide that reduces the frequency and severity of attacks, but does not appear to prevent the progression of interictal symptoms. PERSPECTIVES: This article summarizes current knowledge on episodic ataxia type 1 and 2 and describes briefly the other types of EA. CONCLUSION: Molecular analysis of KCNA1 or CACNA1A provides a confirmation of the diagnosis of EA1 and EA2. Other types remain rare phenotypic variants. Among them, only two genes have been identified: CACNB4 in EA5 and SLC1A3 in EA6 and mutations have been found in a very few cases. No mutation can be detected in some familial cases of episodic ataxia, suggesting further heterogeneity.