A recurrent homozygous LMNA missense variant p.Thr528Met causes atypical progeroid syndrome characterized by mandibuloacral dysostosis, severe muscular dystrophy, and skeletal deformities.

Atypical progeroid syndromes (APS) are premature aging syndromes caused by pathogenic LMNA missense variants, associated with unaltered expression levels of lamins A and C, without accumulation of wild-type or deleted prelamin A isoforms, as observed in Hutchinson-Gilford progeria syndrome (HGPS) or HGPS-like syndromes. A specific LMNA missense variant, (p.Thr528Met), was previously identified in a compound heterozygous state in patients affected by APS and severe familial partial lipodystrophy, whereas heterozygosity was recently identified in patients affected by Type 2 familial partial lipodystrophy. Here, we report four unrelated boys harboring homozygosity for the p.Thr528Met, variant who presented with strikingly homogeneous APS clinical features, including osteolysis of mandibles, distal clavicles and phalanges, congenital muscular dystrophy with elevated creatine kinase levels, and major skeletal deformities. Immunofluorescence analyses of patient-derived primary fibroblasts showed a high percentage of dysmorphic nuclei with nuclear blebs and typical honeycomb patterns devoid of lamin B1. Interestingly, in some protrusions emerin or LAP2α formed aberrant aggregates, suggesting pathophysiology-associated clues. These four cases further confirm that a specific LMNA variant can lead to the development of strikingly homogeneous clinical phenotypes, in these particular cases a premature aging phenotype with major musculoskeletal involvement linked to the homozygous p.Thr528Met variant.

Galanin pathogenic mutations in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a common epilepsy syndrome with a complex etiology. Despite evidence for the participation of genetic factors, the genetic basis of TLE remains largely unknown. A role for the galanin neuropeptide in the regulation of epileptic seizures has been established in animal models more than two decades ago. However, until now there was no report of pathogenic mutations in GAL, the galanin-encoding gene, and therefore its role in human epilepsy was not established. Here, we studied a family with a pair of monozygotic twins affected by TLE and two unaffected siblings born to healthy parents. Exome sequencing revealed that both twins carried a novel de novo mutation (p.A39E) in the GAL gene. Functional analysis revealed that the p.A39E mutant showed antagonistic activity against galanin receptor 1 (GalR1)-mediated response, and decreased binding affinity and reduced agonist properties for GalR2. These findings suggest that the p.A39E mutant could impair galanin signaling in the hippocampus, leading to increased glutamatergic excitation and ultimately to TLE. In a cohort of 582 cases, we did not observe any pathogenic mutations indicating that mutations in GAL are a rare cause of TLE. The identification of a novel de novo mutation in a biologically-relevant candidate gene, coupled with functional evidence that the mutant protein disrupts galanin signaling, strongly supports GAL as the causal gene for the TLE in this family. Given the availability of galanin agonists which inhibit seizures, our findings could potentially have direct implications for the development of anti-epileptic treatment.

Refining the phenotype associated with CASC5 mutation.

Autosomal recessive primary microcephaly is a neurodevelopmental disorder characterized by congenitally reduced head circumference by at least two standard deviations (SD) below the mean for age and gender. It is associated with nonprogressive mental retardation of variable degree, minimal neurological deficit with no evidence of architectural anomalies of the brain. So far, 12 genetic loci (MCPH1-12) and corresponding genes have been identified. Most of these encode centrosomal proteins. CASC5 is one the most recently unravelled genes responsible for MCPH with mutations reported in three consanguineous families of Moroccan origin, all of whom harboured the same CASC5 homozygous mutation (c.6125G>A; p.Met2041Ile). Here, we report the identification, by whole exome sequencing, of the same missense mutation in a consanguineous Algerian family. All patients exhibited a similar clinical phenotype, including congenital microcephaly with head circumferences ranging from -3 to -4 standard deviations (SD) after age 5 years, moderate to severe cognitive impairment, short stature (adult height -3 SD), dysmorphic features included a sloping forehead, thick eyebrows, synophris and a low columella. Severe vermis hypoplasia and a large cyst of the posterior fossa were observed in one patient. Close microsatellite markers showed identical alleles in the Algerian the previously and Moroccan patients. This study confirms the involvement of CASC5 in autosomal recessive microcephaly and supports the hypothesis of a founder effect of the c.6125G>A mutation. In addition, this report refines the phenotype of this newly recognized form of primary microcephaly.

Greater improvement in LRRK2 G2019S patients undergoing Subthalamic Nucleus Deep Brain Stimulation compared to non-mutation carriers.

BACKGROUND: Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) of parkinson's disease (PD) patients has demonstrated to improve motor performance and to reduce dopa-induced dyskinesia. An association between the occurrence of dyskinesias and LRRK2 (leucine-rich repeat kinase 2) G2019S gene mutations has recently been suggested. The aim of this study is to discover the impact of the G2019S mutation (with high incidence in the authors' native Algeria) on the symptom response of PD in patients who underwent STN-DBS. METHODS: We carried out a comparative statistical study for the clinical evaluation and neuropsychological assessment of 27 Algerian PD STN-DBS patients, both G2019S mutation carriers (MC) and non-carriers (NC). A multiple correspondence analysis (MCA) was then conducted to compare the results with those from groups of individuals with similar modalities. RESULTS: The MCA revealed that MC and NC PD patients showed two different patterns of clinical evaluations. The group of idiopathic patients showed some differences compared to the clinical evaluations, depending on gender. No association was found between the G2019S mutation and the Mini Mental State Examination scores (MMSE), and MC patients appeared more susceptible to dyskinesia than NC patients. In NC patients, we found two cases with Parkin mutations who had a different "honeymoon" period and different initial symptoms. The results showed considerable improvement of motor unified parkinson's disease rating scale III (UPDRS-III) in a situation of stimulation without medication in the MC patients with a percentage of improvement (51.1 %) over the required 30 % compared to the NC patients (25.5 %). The same result was observed for the Schwab and England's activities of daily living scale (S and E scale), which thus demonstrated a greater effectiveness of DBS for MC patients than for NC patients. However, the Hoehn and Yahr scale (H and Y Scale) showed the same significance in a situation of stimulation for MC and NC patients. In this later group, the best scores of UPDRS-III were observed for patients with the Parkin mutation before they underwent surgery. CONCLUSIONS: This study shows that surgical treatment probably has a more significant impact on LRRK2 G2019S MC than on idiopathic patients.

Molecular and clinical study of a cohort of 110 Algerian patients with autosomal recessive ataxia.

BACKGROUND: Autosomal recessive cerebellar ataxias (ARCA) are a complex group of neurodegenerative disorders with great genetic and phenotypic heterogeneity, over 30 genes/loci have been associated with more than 20 different clinical forms of ARCA. Genetic heterogeneity combined with highly variable clinical expression of the cerebellar symptoms and overlapping features complicate furthermore the etiological diagnosis of ARCA. The determination of the most frequent mutations and corresponding ataxias, as well as particular features specific to a population, are mandatory to facilitate and speed up the diagnosis process, especially when an appropriate treatment is available. METHODS: We explored 166 patients (115 families) refered to the neurology units of Algiers central hospitals (Algeria) with a cerebellar ataxia phenotype segregating as an autosomal recessive pattern of inheritance. Genomic DNA was extracted from peripheral blood samples and mutational screening was performed by PCR and direct sequencing or by targeted genomic capture and massive parallel sequencing of 57 genes associated with inherited cerebellar ataxia phenotypes. RESULTS: In this work we report the clinical and molecular results obtained on a large cohort of Algerian patients (110 patients/76 families) with genetically determined autosomal recessive ataxia, representing 9 different types of ARCA and 23 different mutations, including 6 novel ones. The five most common ARCA in this cohort were Friedreich ataxia, ataxia with isolated vitamin E deficiency, ataxia with oculomotor apraxia type 2, autosomal recessive spastic ataxia of Charlevoix-Saguenay and ataxia with oculomotor apraxia type 1. CONCLUSION: We report here a large cohort of patients with genetically determined autosomal recessive ataxia and the first study of the genetic context of ARCA in Algeria. This study showed that in Algerian patients, the two most common types of ataxia (Friedreich ataxia and ataxia with isolated vitamin E deficiency) coexist with forms that may be less common or underdiagnosed. To refine the genotype/phenotype correlation in rare and heteregeneous diseases as autosomal recessive ataxias, more extensive epidemiological investigations and reports are necessary as well as more accurate and detailed clinical characterizations. The use of standardized clinical and molecular protocols would thus enable a better knowledge of the different forms of ARCA.

Mutation in TTI2 reveals a role for triple T complex in human brain development.

Tel2-interacting proteins 1 and 2 (TTI1 and TTI2) physically interact with telomere maintenance 2 (TEL2) to form a conserved trimeric complex called the Triple T complex. This complex is a master regulator of phosphoinositide-3-kinase-related protein kinase (PIKKs) abundance and DNA damage response signaling. Using a combination of autozygosity mapping and high-throughput sequencing in a large consanguineous multiplex family, we found that a missense c.1307T>A/p.I436N mutation in TTI2 causes a human autosomal recessive condition characterized by severe cognitive impairment, microcephaly, behavioral troubles, short stature, skeletal anomalies, and facial dysmorphic features. Immunoblotting experiment showed decreased amount of all Triple T complex components in the patient skin fibroblasts. Consistently, a drastically reduced steady-state level of all PIKKs tested was also observed in the patient cells. Combined with previous observations, these findings emphasises the role of the TTI2 gene in the etiology of intellectual disability and further support the role of PIKK signaling in brain development and functioning.

Clinical, Biomarker, and Molecular Delineations and Genotype-Phenotype Correlations of Ataxia With Oculomotor Apraxia Type 1.

Importance: Ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive cerebellar ataxia due to mutations in the aprataxin gene (APTX) that is characterized by early-onset cerebellar ataxia, oculomotor apraxia, axonal motor neuropathy, and eventual decrease of albumin serum levels. Objectives: To improve the clinical, biomarker, and molecular delineation of AOA1 and provide genotype-phenotype correlations. Design, Setting, and Participants: This retrospective analysis included the clinical, biological (especially regarding biomarkers of the disease), electrophysiologic, imaging, and molecular data of all patients consecutively diagnosed with AOA1 in a single genetics laboratory from January 1, 2002, through December 31, 2014. Data were analyzed from January 1, 2015, through January 31, 2016. Main Outcomes and Measures: The clinical, biological, and molecular spectrum of AOA1 and genotype-phenotype correlations. Results: The diagnosis of AOA1 was confirmed in 80 patients (46 men [58%] and 34 women [42%]; mean [SD] age at onset, 7.7 [7.4] years) from 51 families, including 57 new (with 8 new mutations) and 23 previously described patients. Elevated levels of α-fetoprotein (AFP) were found in 33 patients (41%); hypoalbuminemia, in 50 (63%). Median AFP level was higher in patients with AOA1 (6.0 ng/mL; range, 1.1-17.0 ng/mL) than in patients without ataxia (3.4 ng/mL; range, 0.8-17.2 ng/mL; P < .01). Decreased albumin levels (ρ = -0.532) and elevated AFP levels (ρ = 0.637) were correlated with disease duration. The p.Trp279* mutation, initially reported as restricted to the Portuguese founder haplotype, was discovered in 53 patients with AOA1 (66%) with broad white racial origins. Oculomotor apraxia was found in 49 patients (61%); polyneuropathy, in 74 (93%); and cerebellar atrophy, in 78 (98%). Oculomotor apraxia correlated with the severity of ataxia and mutation type, being more frequent with deletion or truncating mutations (83%) than with presence of at least 1 missense variant (17%; P < .01). Mean (SD) age at onset was higher for patients with at least 1 missense mutation (17.7 [11.4] vs 5.2 [2.6] years; P < .001). Conclusions and Relevance: The AFP level, slightly elevated in a substantial fraction of patients, may constitute a new biomarker for AOA1. Oculomotor apraxia may be an optional finding in AOA1 and correlates with more severe disease. The p.Trp279* mutation is the most frequent APTX mutation in the white population. APTX missense mutations may be associated with a milder phenotype.

Familial epilepsy in Algeria: Clinical features and inheritance profiles.

PURPOSE: To document the clinical characteristics and inheritance pattern of epilepsy in multigeneration Algerian families. METHODS: Affected members from extended families with familial epilepsy were assessed at the University Hospital of Oran in Algeria. Available medical records, neurological examination, electroencephalography and imaging data were reviewed. The epilepsy type was classified according to the criteria of the International League Against Epilepsy and modes of inheritance were deduced from pedigree analysis. RESULTS: The study population included 40 probands; 23 male (57.5%) and 17 female subjects (42.5%). The mean age of seizure onset was 9.5 ± 6.1 years. According to seizure onset, 16 patients (40%) had focal seizures and 20 (50%) had generalized seizures. Seizure control was achieved for two patients (5%) for 10 years, while 28 (70%) were seizure-free for 3 months. Eleven patients (27.5%) had prior febrile seizures, 12 were diagnosed with psychiatric disorders and four families had syndromic epilepsy. The consanguinity rate among parents of affected was 50% with phenotypic concordance observed in 25 families (62.5%). Pedigree analysis suggested autosomal dominant (AD) inheritance with or without reduced penetrance in 18 families (45%), probable autosomal recessive (AR) inheritance in 14 families (35%), and an X-linked recessive inheritance in one family. CONCLUSION: This study reveals large Algerian families with multigenerational inheritance of epilepsy. Molecular testing such as exome sequencing would clarify the genetic basis of epilepsy in some of our families.

Consanguinity and epilepsy in Oran, Algeria: A case-control study.

PURPOSE: The goal of this case-control study was to identify the significance of consanguinity and other risk factors for epilepsy in Oran, Algeria. METHODS: Unrelated epileptic patients upwards of 16 years, who attended the Neurology Department between October 2013 and March 2014 were included in the study. Controls, matched for age and sex, were selected among non-epileptic patients attending the same department during the same period. The risk factors evaluated were: consanguinity, family history of epilepsy, perinatal complications, infection of the central nervous system, mental retardation, neurological impairment, history of febrile seizures, severe head trauma, cerebrovascular diseases, and addiction. RESULTS: 101 cases and 202 controls participated in the study. Multivariate logistic regression identified five factors significantly associated with epilepsy: first-degree of consanguinity (odds ratio (OR)=2.15), history of epilepsy in first-degree relatives (OR=4.03), antecedent of febrile seizures (OR=5.38), severe head injury (OR=2.94) and mental retardation (OR=9.32). CONCLUSION: Consanguinity, family history of epilepsy, history of febrile seizures, severe head trauma and mental retardation are risk factors for epilepsy. The implementation of a strategy for prevention and awareness of the impact of consanguineous marriages as well as genetic counseling for couples with a family history of epilepsy are needed.

Phenotypic spectrum and prevalence of INPP5E mutations in Joubert syndrome and related disorders.

Joubert syndrome and related disorders (JSRD) are clinically and genetically heterogeneous ciliopathies sharing a peculiar midbrain-hindbrain malformation known as the 'molar tooth sign'. To date, 19 causative genes have been identified, all coding for proteins of the primary cilium. There is clinical and genetic overlap with other ciliopathies, in particular with Meckel syndrome (MKS), that is allelic to JSRD at nine distinct loci. We previously identified the INPP5E gene as causative of JSRD in seven families linked to the JBTS1 locus, yet the phenotypic spectrum and prevalence of INPP5E mutations in JSRD and MKS remain largely unknown. To address this issue, we performed INPP5E mutation analysis in 483 probands, including 408 JSRD patients representative of all clinical subgroups and 75 MKS fetuses. We identified 12 different mutations in 17 probands from 11 JSRD families, with an overall 2.7% mutation frequency among JSRD. The most common clinical presentation among mutated families (7/11, 64%) was Joubert syndrome with ocular involvement (either progressive retinopathy and/or colobomas), while the remaining cases had pure JS. Kidney, liver and skeletal involvement were not observed. None of the MKS fetuses carried INPP5E mutations, indicating that the two ciliopathies are not allelic at this locus.

Compound heterozygous ASPM mutations associated with microcephaly and simplified cortical gyration in a consanguineous Algerian family.

Homozygous mutations in the ASPM gene are a major cause of autosomal recessive primary microcephaly (MCPH). Here we report on a consanguineous Algerian family in which three out of five children presented with severe microcephaly, simplified cortical gyration, mild to severe mental retardation and low to low-normal birth weight. Given the parental consanguinity with the unaffected parents being third cousins once removed, the most probable pattern of inheritance was autosomal recessive. Linkage and mutational analyses identified compound heterozygous truncating mutations within the ASPM gene segregating with MCPH (c.2389C>T [p.Arg797X] and c.7781_7782delAG [p.Gln2594fsX6]). These results highlight some of the pitfalls of genetic analysis in consanguineous families. They also suggest that low birth weight may be a feature of MCPH, a finding that needs confirmation, and confirm that ASPM mutations are associated with simplified cortical gyration.

Mutations in FGD4 encoding the Rho GDP/GTP exchange factor FRABIN cause autosomal recessive Charcot-Marie-Tooth type 4H.

Charcot-Marie-Tooth (CMT) disorders are a clinically and genetically heterogeneous group of hereditary motor and sensory neuropathies characterized by muscle weakness and wasting, foot and hand deformities, and electrophysiological changes. The CMT4H subtype is an autosomal recessive demyelinating form of CMT that was recently mapped to a 15.8-Mb region at chromosome 12p11.21-q13.11, in two consanguineous families of Mediterranean origin, by homozygosity mapping. We report here the identification of mutations in FGD4, encoding FGD4 or FRABIN (FGD1-related F-actin binding protein), in both families. FRABIN is a GDP/GTP nucleotide exchange factor (GEF), specific to Cdc42, a member of the Rho family of small guanosine triphosphate (GTP)-binding proteins (Rho GTPases). Rho GTPases play a key role in regulating signal-transduction pathways in eukaryotes. In particular, they have a pivotal role in mediating actin cytoskeleton changes during cell migration, morphogenesis, polarization, and division. Consistent with these reported functions, expression of truncated FRABIN mutants in rat primary motoneurons and rat Schwann cells induced significantly fewer microspikes than expression of wild-type FRABIN. To our knowledge, this is the first report of mutations in a Rho GEF protein being involved in CMT.

Homozygous defects in LMNA, encoding lamin A/C nuclear-envelope proteins, cause autosomal recessive axonal neuropathy in human (Charcot-Marie-Tooth disorder type 2) and mouse.

The Charcot-Marie-Tooth (CMT) disorders comprise a group of clinically and genetically heterogeneous hereditary motor and sensory neuropathies, which are mainly characterized by muscle weakness and wasting, foot deformities, and electrophysiological, as well as histological, changes. A subtype, CMT2, is defined by a slight or absent reduction of nerve-conduction velocities together with the loss of large myelinated fibers and axonal degeneration. CMT2 phenotypes are also characterized by a large genetic heterogeneity, although only two genes---NF-L and KIF1Bbeta---have been identified to date. Homozygosity mapping in inbred Algerian families with autosomal recessive CMT2 (AR-CMT2) provided evidence of linkage to chromosome 1q21.2-q21.3 in two families (Zmax=4.14). All patients shared a common homozygous ancestral haplotype that was suggestive of a founder mutation as the cause of the phenotype. A unique homozygous mutation in LMNA (which encodes lamin A/C, a component of the nuclear envelope) was identified in all affected members and in additional patients with CMT2 from a third, unrelated family. Ultrastructural exploration of sciatic nerves of LMNA null (i.e., -/-) mice was performed and revealed a strong reduction of axon density, axonal enlargement, and the presence of nonmyelinated axons, all of which were highly similar to the phenotypes of human peripheral axonopathies. The finding of site-specific amino acid substitutions in limb-girdle muscular dystrophy type 1B, autosomal dominant Emery-Dreifuss muscular dystrophy, dilated cardiomyopathy type 1A, autosomal dominant partial lipodystrophy, and, now, AR-CMT2 suggests the existence of distinct functional domains in lamin A/C that are essential for the maintenance and integrity of different cell lineages. To our knowledge, this report constitutes the first evidence of the recessive inheritance of a mutation that causes CMT2; additionally, we suggest that mutations in LMNA may also be the cause of the genetically overlapping disorder CMT2B1.