Clinical and genetic characterisation of a large Indian congenital myasthenic syndrome cohort.

Congenital myasthenic syndromes (CMS) are a rare group of inherited disorders caused by gene defects associated with the neuromuscular junction and potentially treatable with commonly available medications such as acetylcholinesterase inhibitors and ß2 adrenergic receptor agonists. In this study, we identified and genetically characterized the largest cohort of CMS patients from India to date. Genetic testing of clinically suspected patients evaluated in a South Indian hospital during the period 2014-19 was carried out by standard diagnostic gene panel testing or using a two-step method that included hotspot screening followed by whole-exome sequencing. In total, 156 genetically diagnosed patients (141 families) were characterized and the mutational spectrum and genotype-phenotype correlation described. Overall, 87 males and 69 females were evaluated, with the age of onset ranging from congenital to fourth decade (mean 6.6 ± 9.8 years). The mean age at diagnosis was 19 ± 12.8 (1-56 years), with a mean diagnostic delay of 12.5 ± 9.9 (0-49 years). Disease-causing variants in 17 CMS-associated genes were identified in 132 families (93.6%), while in nine families (6.4%), variants in genes not associated with CMS were found. Overall, postsynaptic defects were most common (62.4%), followed by glycosylation defects (21.3%), synaptic basal lamina genes (4.3%) and presynaptic defects (2.8%). Other genes found to cause neuromuscular junction defects (DES, TEFM) in our cohort accounted for 2.8%. Among the individual CMS genes, the most commonly affected gene was CHRNE (39.4%), followed by DOK7 (14.4%), DPAGT1 (9.8%), GFPT1 (7.6%), MUSK (6.1%), GMPPB (5.3%) and COLQ (4.5%). We identified 22 recurrent variants in this study, out of which eight were found to be geographically specific to the Indian subcontinent. Apart from the known common CHRNE variants p.E443Kfs*64 (11.4%) and DOK7 p.A378Sfs*30 (9.3%), we identified seven novel recurrent variants specific to this cohort, including DPAGT1 p.T380I and DES c.1023+5G>A, for which founder haplotypes are suspected. This study highlights the geographic differences in the frequencies of various causative CMS genes and underlines the increasing significance of glycosylation genes (DPAGT1, GFPT1 and GMPPB) as a cause of neuromuscular junction defects. Myopathy and muscular dystrophy genes such as GMPPB and DES, presenting as gradually progressive limb girdle CMS, expand the phenotypic spectrum. The novel genes MACF1 and TEFM identified in this cohort add to the expanding list of genes with new mechanisms causing neuromuscular junction defects.

Phenotype-genotype spectrum of a cohort of congenital muscular dystrophies: a single-centre experience from India.

Congenital Muscular Dystrophies (CMD) are phenotypically and genotypically heterogenous disorders with a prevalence of 0.68 to 2.5/100,000, contributing to significant morbidity and mortality. We aimed to study the phenotype-genotype spectrum of genetically confirmed cases of CMD. This was retrospective & descriptive study done at a quaternary care referral centre in south India. Genetically confirmed cases of CMDs seen between 2010 to 2020 were recruited. Detailed clinical history, including pedigree, MRI brain/muscle, next generation sequencing results of 61 CMD cases were collected. Collagen VI-related dystrophy (COL6-RD) (36%) was the most common subtype with variants frequently seen in COL6A1 gene. Other CMDs identified were LAMA2-RD (26%), alpha-dystroglycan-RD (19%), LMNA-RD (8%), CHKB-RD (7%) and SEPN1-RD (3%). Similar to previous cohorts, overall, missense variants were common in COL-6 RD. Variants in triple helical domain (THD) of COL6-RD were seen in 11/22 patients, 5 of whom were ambulatory contrary to previous literature citing severe disease with these variants. However, our follow-up period was shorter. In the LAMA2-RD, 2/16 patients were ambulatory & all 16 carried truncating variants. Among dystroglycanopathies, FKRP-RD was the commonest. Milder phenotype of FKRP- RD was observed with variant c.1343C > T, which was also a recurrent variant in our cohort. p.Arg249Trp variant in LMNA-CMD associated with early loss of ambulation was also identified in 1/5 of our patients who expired at age 2.8 years. The current retrospective series provides detailed clinical features and mutation patterns of genetically confirmed cases of CMD from a single center in India.

Cognitive and Behavioral Profile of Patients with Amyotrophic Lateral Sclerosis Spectrum in the Indian Context.

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is characterized by motor, cognitive, and behavioral impairment. There is a paucity of evidence about the cognitive/behavioral features of ALS patients from India. We aimed to investigate the cognitive/behavioral profile of ALS spectrum disorders in the Indian context. METHODS: Sixty patients with ALS spectrum and 40 age-, gender-, and education-matched healthy controls were recruited. The scales used were Addenbrooke's Cognitive Examination (ACE-III), Clinical Dementia Rating (CDR) scale, and Frontal Systems Behavior (FrSBe) Scale. RESULTS: The mean age of the overall cohort was 55 years, and male-to-female ratio was 2.5:1. The mean duration of illness of the cohort was 16 months. Patients were classified as ALS with normal cognition (ALS-cn, n = 21), mild cognitive or behavioral deficits (ALS-ci/-bi, n = 28), and frontotemporal dementia (ALS-FTD, n = 11). ALS-cn had poorer scores compared to healthy controls in global cognition, memory, and language (p < 0.05). ALS-ci/-bi performed poorer than healthy controls on all cognitive domains (p < 0.05). ALS-FTD had poorer scores than healthy controls and ALS-cn on all cognitive domains (p < 0.001). Behavioral assessment showed an increase in apathy among all subtypes. ALS-FTD showed significant worsening in disinhibition and executive function compared to ALS-cn and ALS-ci/-bi. CONCLUSION: Our findings suggest that there are key cognitive and behavior characteristics in Indian patients with ALS spectrum. This further strengthens the evidence of a cognitive continuum in ALS and FTD in a diverse context and highlights the importance of meticulous evaluation and correct diagnosis that would assist in better management.

Clinical spectrum, biochemical profile and disease progression of Kennedy disease in an Indian cohort.

BACKGROUND: Kennedy disease (KD) is a slowly progressive lower motor neuron degenerative disease. The prevalence of KD is unknown in India. AIM: To describe the phenotypic and laboratory features of an Indian cohort of KD patients. METHODS: A retrospective study was done on seven genetically confirmed KD patients based on demographic, clinical and laboratory details. RESULTS: Mean age at onset and presentation was 37 ± 11.9 and 44.6 ± 13.5 years respectively. Progressive asymmetric proximal and distal limb weakness was the commonest symptom (57.1%). All patients had motor symptoms along with non-specific symptoms such as cramps from the onset. Easy fatigability, decremental response along with ptosis were noted in two patients, which was a novel finding. Gynaecomastia and tongue wasting with fasciculations were universal findings. All five patients with nerve conduction studies showed sensorimotor neuropathy. Magnetic resonance imaging muscle done in two patients showed a prominent moth-eaten appearance in the thigh and posterior leg compartment in one patient. The mean cytosine-adenine-guanine repeats were 44 ± 3.7, and there was no association between age of onset or severity with repeat length. Only one patient required an assistive device for ambulation after 15 years of symptom onset. CONCLUSIONS: This study showed phenotypic heterogeneity in the Indian cohort. The age of onset was earlier with a slowly progressive indolent course as compared with other ethnic cohorts. This highlights the importance of considering the KD diagnosis in patients with the indolent course and suspected ALS diagnosis even with ptosis and fatigability in an appropriate clinical context.

Genotype-phenotype correlation and natural history study of dysferlinopathy: a single-centre experience from India.

Dysferlinopathies are a group of limb-girdle muscular dystrophies causing significant disability in the young population. There is a need for studies on large cohorts to describe the clinical, genotypic and natural history in our subcontinent. To describe and correlate the clinical, genetic profile and natural history of genetically confirmed dysferlinopathies. We analysed a retrospective cohort of patients with dysferlinopathy from a single quaternary care centre in India. A total of 124 patients with dysferlinopathy were included (40 females). Median age at onset and duration of illness were 21 years (range, 13-50) and 48 months (range, 8-288), respectively. The average follow-up period was 60 months (range, 12-288). Fifty-one percent had LGMD pattern of weakness at onset; 23.4% each had Miyoshi and proximo-distal type while isolated hyperCKemia was noted in 1.6%. About 60% were born to consanguineous parents and 26.6% had family history of similar illness. Twenty-three patients (18.6%) lost ambulation at follow-up; the median time to loss of independent ambulation was 120 months (range, 72-264). Single-nucleotide variants (SNVs) constituted 78.2% of patients; INDELs 14.5% and 7.3% had both SNVs and INDELs. Earlier age at onset was noted with SNVs. There was no correlation between the other clinical parameters and ambulatory status with the genotype. Thirty-seven (45.7%) novel pathogenic/likely pathogenic (P/LP) variants were identified out of a total of 81 variations. The c.3191G > A variant was the most recurrent mutation. Our cohort constitutes a clinically and genetically heterogeneous group of dysferlinopathies. There is no significant correlation between the clinico-genetic profile and the ambulatory status.

High diagnostic rate of trio exome sequencing in consanguineous families with neurogenetic diseases.

Consanguineous marriages have a prevalence rate of 24% in Turkey. These carry an increased risk of autosomal recessive genetic conditions, leading to severe disability or premature death, with a significant health and economic burden. A definitive molecular diagnosis could not be achieved in these children previously, as infrastructures and access to sophisticated diagnostic options were limited. We studied the cause of neurogenetic disease in 246 children from 190 consanguineous families recruited in three Turkish hospitals between 2016 and 2020. All patients underwent deep phenotyping and trio whole exome sequencing, and data were integrated in advanced international bioinformatics platforms. We detected causative variants in 119 known disease genes in 72% of families. Due to overlapping phenotypes 52% of the confirmed genetic diagnoses would have been missed on targeted diagnostic gene panels. Likely pathogenic variants in 27 novel genes in 14% of the families increased the diagnostic yield to 86%. Eighty-two per cent of causative variants (141/172) were homozygous, 11 of which were detected in genes previously only associated with autosomal dominant inheritance. Eight families carried two pathogenic variants in different disease genes. De novo (9.3%), X-linked recessive (5.2%) and compound heterozygous (3.5%) variants were less frequent compared to non-consanguineous populations. This cohort provided a unique opportunity to better understand the genetic characteristics of neurogenetic diseases in a consanguineous population. Contrary to what may be expected, causative variants were often not on the longest run of homozygosity and the diagnostic yield was lower in families with the highest degree of consanguinity, due to the high number of homozygous variants in these patients. Pathway analysis highlighted that protein synthesis/degradation defects and metabolic diseases are the most common pathways underlying paediatric neurogenetic disease. In our cohort 164 families (86%) received a diagnosis, enabling prevention of transmission and targeted treatments in 24 patients (10%). We generated an important body of genomic data with lasting impacts on the health and wellbeing of consanguineous families and economic benefit for the healthcare system in Turkey and elsewhere. We demonstrate that an untargeted next generation sequencing approach is far superior to a more targeted gene panel approach, and can be performed without specialized bioinformatics knowledge by clinicians using established pipelines in populations with high rates of consanguinity.

Clinical, genetic profile and disease progression of sarcoglycanopathies in a large cohort from India: high prevalence of SGCB c.544A > C.

The clinico-genetic architecture of sarcoglycanopathies in Indian patients is reported only as short series. In the present study, we aimed to investigate the clinical picture, genetic basis, and disease progression of patients genetically confirmed to have sarcoglycanopathy. Next-generation sequencing was performed in 68 probands with suspected sarcoglycanopathy. A total of 35 different variants were detected in the sarcoglycan genes in 68 probands (M = 37; age range, 5-50 years). Consanguinity was present in 44 families. Thirty-two variants are predicted to be pathogenic/likely pathogenic, among which 25 (78.13%) are reported, and 7 (21.87%) are novel. The clinical diagnosis was confirmed in a total of 64 (94.12%) probands with biallelic variations [SGCA(n=18); SGCB(n=34); SGCG(n=7); SGCD(n=5)]. The most common mutation was c.544A > C (p.Thr182Pro) in SGCB, and detected in 20 patients (29.42%). The majority of pathogenic mutations are homozygous (n = 30; 93.75%). Variants in 4 cases are of uncertain significance. Thirty-three patients lost ambulation at a mean age of 15.12 ± 9.47 years, after 7.76 ± 5.95 years into the illness. Only 2 patients had cardiac symptoms, and one had respiratory muscle involvement. The results from this study suggest that mutations in SGCB are most common, followed by SGCA, SGCG, and SGCD. The novel variations identified in this study expand the mutational spectrum of sarcoglycanopathies. To the best of our knowledge, this is the first study from India to describe a large cohort of genetically confirmed patients with sarcoglycanopathy and report its disease progression.

Congenital myasthenic syndrome: Correlation between clinical features and molecular diagnosis.

OBJECTIVES: To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis. METHODS: Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis. RESULTS: Seventy-nine patients (68 families) were included in the cohort: 48 in group A, 23 in group B and 8 in group C. Fifty-one were considered confirmed CMS (30 CHRNE, 5 RAPSN, 4 COL13A1, 3 DOK7, 3 COLQ, 2 GFPT1, 1 CHAT, 1 SCN4A, 1 GMPPB, 1 CHRNA1), 7 probable CMS, 5 non-CMS and 16 unsolved. The chance of a confirmed molecular diagnosis of CMS was significantly higher for group A and lower for group C. Some individual clinical features, alterations on biopsy and electrophysiology enhanced specificity for CMS. Muscle imaging showed at least mild alterations in the majority of confirmed cases, with preferential involvement of soleus, especially in CHRNE CMS. CONCLUSIONS: Stricter clinical criteria increase the chance of confirming a CMS diagnosis, but may lose sensitivity, especially for some specific genes.

Novel TBK1 variant associated with Frontotemporal Dementia overlap syndrome.

BACKGROUND: Recently, TANK binding kinase 1 (TBK1) mutation has been reported as a causative gene for overlap frontotemporal dementia (FTD)-amyotrophic lateral sclerosis (ALS) syndrome. However, there are no reports from families of South Asian ethnicity. OBJECTIVE: To report a case study of a family with the proband having overlap FTD-ALS syndrome caused by a novel TBK1 variant. MATERIALS AND METHODS: Clinical, brain imaging, genetic analysis and laboratory data of the patient with FTD-ALS were performed. In addition, family-based segregation analysis of identified novel variants was also done. RESULTS: This study pertains to genetic analysis in 11 members in a family with only one member affected with overlap FTD-ALS syndrome. The whole-exome sequencing analysis in the symptomatic member showed a novel loss-of-function (LoF) variant c.1810G>T(p.E604X) in the TBK1 gene. Neuroimaging showed a pattern of asymmetric frontotemporal atrophy and hypometabolism. Segregation analysis of the variation demonstrated its presence in several family members, although none of the other members was symptomatic. Further, we observed another missense variation in the NEFH gene (p.Pro683Leu) which was seen in the symptomatic and two asymptomatic family members, the pathogenicity of which is unclear. CONCLUSION: This is the first study of a rare novel TBK1 variant associated with FTD-ALS from India. Asymptomatic family members with the variant have important clinical implications and necessitate the genetic evaluation and long-term follow-up of family members of patients detected with TBK1 mutations. Therefore, although infrequent, genetic screening for the TBK1 gene should be considered when encountering overlap FTD syndromes.

Muscle ultrasonography in detecting fasciculations: A noninvasive diagnostic tool for amyotrophic lateral sclerosis.

BACKGROUND AND OBJECTIVES: Muscle ultrasound (MUS) is an emerging noninvasive tool to identify fasciculations in amyotrophic lateral sclerosis (ALS). We assessed the utility of MUS in detecting fasciculations in suspected ALS patients. METHODS: Thirty-three patients (25 men) with possible (n = 7), probable (n = 12), or definite ALS according to Awaji criteria were studied. Electromyography was done in biceps brachii, quadriceps, and thoracic paraspinal muscles and MUS in biceps, triceps, deltoid, abductor-digiti-minimi, quadriceps, hamstrings, tibialis anterior, thoracic paraspinal, and tongue muscles. RESULTS: The age at onset and illness duration was 49.73 ± 12.7 years and 13.57 ± 9.7 months, respectively. Limb-onset = 24 patients (72.7%) and bulbar-onset = 9 (27.3%). Totally 561 muscles were examined by MUS. Fasciculations were detected in 84.3% of muscles, 98.4% with and 73% without clinical fasciculations (p < 0.001). Fasciculation detection rate (FDR) by MUS was significantly higher in muscles with wasting (95.6%) than without wasting (77.6%, p < 0.001). Compared with EMG, FDR was significantly higher with MUS in quadriceps (81.8% vs. 51.5%, p = 0.002) and thoracic paraspinal muscles (75.8% vs. 42.4%, p = 0.013). The proportion of patients with definite ALS increased from 42% by clinical examination to 70% after combining EMG and MUS findings. CONCLUSIONS: MUS is more sensitive in detecting fasciculations than electromyography (EMG) and provides a safer, faster, painless, and noninvasive alternative to EMG in detecting fasciculations in ALS.

Diaphragmatic ultrasound: Prospects as a tool to assess respiratory muscle involvement in amyotrophic lateral sclerosis.

BACKGROUND: Ultrasonography (USG) of the diaphragm is a promising alternative to pulmonary function tests (PFT) for assessing respiratory function in amyotrophic lateral sclerosis/motor neuron disease (ALS/MND). METHODS: We studied 33 patients fulfilling Awaji criteria (definite = 14; probable = 12; possible = 7) and 33 age and gender-matched controls. Diaphragm thickness was measured using USG at the end of expiration (DTex) and end of inspiration (DTin). The thickness ratio (TR) was calculated as DTin/DTex. The mean age at onset and duration were 49.73 ± 12.7 years and 13.57 ± 9.7 months, respectively. Men = 25 (75.8%); Limb onset ALS/MND = 24 patients (72.7%); bulbar onset = 9 (27.3%). RESULTS: Compared to controls, ALS/MND patients had reduced mean DTex (2.22 ± 0.29 mm vs. 2.02 ± 0.32 mm, p = .012) and DTin (4.0 ± 0.71 mm vs. 3.41 ± 0.38 mm, p < .001). PFTs done in 31 patients showed restrictive abnormality in 80.6%. Significant positive correlation was seen between percentage of predicted forced vital capacity (FVC%) and DTin (p = .009) and TR (p = .037) but not with DTex (p = .852). No significant correlation was seen between diaphragmatic thickness and other PFT parameters or ALSFRS scores. CONCLUSION: The diaphragmatic thickness showed a significant decrease in ALS/MND as compared to controls. End-inspiratory diaphragmatic thickness and TR correlated well with %FVC. Thus, diaphragmatic USG could be a potential alternative to PFTs in assessing respiratory function in ALS/MND patients having the advantage of less patient participation and ease of performing in late stages of ALS/MND.

A founder mutation in the GMPPB gene [c.1000G > A (p.Asp334Asn)] causes a mild form of limb-girdle muscular dystrophy/congenital myasthenic syndrome (LGMD/CMS) in South Indian patients.

Twelve patients from seven unrelated South Indian families with a limb-girdle muscular dystrophy-congenital myasthenic syndrome (LGMD/CMS) phenotype and recessive inheritance underwent deep clinical phenotyping, electrophysiological evaluation, muscle histopathology, and next-generation sequencing/Sanger sequencing-based identification of the genetic defect. Homozygosity mapping was performed using high-throughput genome-wide genotyping for mapping the mutation and to evaluate the founder effect. The age of disease onset among patients ranged from childhood to 40 years of age. The key clinical manifestations observed were progressive fatigable limb-girdle weakness, muscle hypertrophy/atrophy, and preferential weakness in a dystrophic pattern. The ages at last follow-up ranged from 30 to 64 years; nine were independently ambulant, two required assistance, and one was wheelchair-bound. Lower limb muscle MRI showed varying degrees of fat replacement in the glutei, hamstrings, anterior leg muscles, and medial gastrocnemius. All patients showed significant decrement on repetitive nerve stimulation (RNS). Muscle biopsy in 7 patients revealed varying degrees of dystrophic and neurogenic changes. Treatment with pyridostigmine and/or salbutamol resulted in variable improvement in 10 patients. Genetic analysis showed an identical homozygous GMPPB mutation c.1000G > A (p.Asp334Asn) in all affected patients. A region of homozygosity (6Mbp) was observed flanking the c.1000G > A change in carrier chromosomes. This study identifies c.1000G > A in GMPPB as a common founder mutation in an ethnic community of South Indian descent with milder yet variable degree of clinical presentation of GMPPB-associated LGMD-CMS.

Megaconial congenital muscular dystrophy secondary to novel CHKB mutations resemble atypical Rett syndrome.

Megaconial congenital muscular dystrophy (CMD)(OMIM #602541), related to CHKB mutation, is a rare autosomal recessive disorder. To date, only 35 confirmed patients are recorded. We present a detailed description of the clinical, histopathological, imaging, and genetic findings of five children from four Indian families. The children had moderate-to-severe autistic behavior, hand stereotypies, and global developmental delay mimicking atypical Rett syndrome. In addition, generalized hypotonia was a common initial finding. The progression of muscle weakness was variable, with two patients having a milder phenotype and three having a severe form. Interestingly, the majority did not attain sphincter control. Only patient 1 had classical ichthyotic skin changes. Muscle biopsy in two patients showed a myopathic pattern with characteristic peripherally placed enlarged mitochondria on modified Gomori trichrome stain and electron microscopy. Genetic analysis in these patients identified three novel null mutations in CHKB [c.1027dupA (p.Ser343LysfsTer86);c.224 + 1G > T (5' splice site); c.1123C > T (p.Gln375Ter)] and one reported missense mutation, c.581G > A (p.Arg194Gln), all in the homozygous state. Megaconial CMD, although rare, forms an important group with a complex phenotypic presentation and accounted for 5.5% of our genetically confirmed CMD patients. Atypical Rett syndrome-like presentation may be a clue towards CHKB-related disorder.

Whole-exome analyses of congenital muscular dystrophy and congenital myopathy patients from India reveal a wide spectrum of known and novel mutations.

BACKGROUND AND PURPOSE: Congenital muscular dystrophies (CMDs) and congenital myopathies (CMs) are a group of genetically and clinically heterogeneous degenerative primary muscle disorders with onset at birth or during infancy. Due to vast heterogeneity, clinical examination and protein-based analyses often fail to identify the genetic causes of these diseases. The aim of this study was to genetically diagnose a cohort of 36 difficult-to-diagnose CMD and CM cases of Indian origin using next-generation sequencing methods. METHODS: Whole-exome sequencing (WES) was performed to identify pathogenic mutations in previously reported CMD and CM-related genes using variant calling and stringent variant filtration process. Subsequently, in silico homology modelling and molecular dynamics simulations (MDS) studies were undertaken for a number of novel and missense variants. RESULTS: A total of 33 and 21 rare and deleterious mutations were identified in 28 genes previously reported in CMD and CM based on OMIM, ClinVar and Orphanet, respectively. We could accurately diagnose 54% patients (n = 12/22) in the CMD group and 35% patients (n = 5/14) in the CM group. Furthermore, MDS studies for mutations located in LMNA, LAMA2 and RYR1 suggest that the wild-type proteins are more stable than their mutant counterparts, implying a potential mechanism of pathogenesis. CONCLUSION: The WES findings led us to identify reported as well as novel variants for the first time in Indian patients with CMD and CM. This allowed us to achieve an accurate genetic diagnosis, which was difficult using conventional diagnostic tools. Transferring these WES findings to clinical practice will help guide clinical care of the affected patients and inform genetic counselling.

Novel variants broaden the phenotypic spectrum of PLEKHG5-associated neuropathies.

BACKGROUND AND PURPOSE: Pathogenic variants in PLEKHG5 have been reported to date to be causative in three unrelated families with autosomal recessive intermediate Charcot-Marie-Tooth disease (CMT) and in one consanguineous family with spinal muscular atrophy (SMA). PLEKHG5 is known to be expressed in the human peripheral nervous system, and previous studies have shown its function in axon terminal autophagy of synaptic vesicles, lending support to its underlying pathogenetic mechanism. Despite this, there is limited knowledge of the clinical and genetic spectrum of disease. METHODS: We leverage the diagnostic utility of exome and genome sequencing and describe novel biallelic variants in PLEKHG5 in 13 individuals from nine unrelated families originating from four different countries. We compare our phenotypic and genotypic findings with a comprehensive review of cases previously described in the literature. RESULTS: We found that patients presented with variable disease severity at different ages of onset (8-25 years). In our cases, weakness usually started proximally, progressing distally, and can be associated with intermediate slow conduction velocities and minor clinical sensory involvement. We report three novel nonsense and four novel missense pathogenic variants associated with these PLEKHG5-associated neuropathies, which are phenotypically spinal muscular atrophy (SMA) or intermediate Charcot-Marie-Tooth disease. CONCLUSIONS: PLEKHG5-associated neuropathies should be considered as an important differential in non-5q SMAs even in the presence of mild sensory impairment and a candidate causative gene for a wide range of hereditary neuropathies. We present this series of cases to further the understanding of the phenotypic and molecular spectrum of PLEKHG5-associated diseases.

Palliative Care in Duchenne Muscular Dystrophy: A Study on Parents' Understanding.

INTRODUCTION: Duchene muscular dystrophy (DMD) is a neuromuscular disease of childhood, which has clear progression. The international standardized care guidelines for DMD suggest that palliative care is essential for the affected children. OBJECTIVE: To explore the parent's understanding of palliative care services available for children with DMD and the challenges faced by them in utilizing the same. METHODS: A cross-sectional qualitative exploratory study was conducted among six families of boys diagnosed with DMD. A semi-structured interview guide with prompts was used to conduct in-depth interviews which lasted for an average of 1 h. Thematic analysis was done to identify the pattern or themes. RESULTS: The major themes identified were "palliative care, living with DMD, Awareness about palliative care services and challenges." Awareness about palliative care services is the dominant theme identified as influencing rest of the experiences narrated by the parents of children with DMD. DISCUSSION: Integration of palliative care services from an early stage of the illness can help the child to make transition from one stage to another stage of the illness. To ensure the utilization of the available palliative care services, there is a need to create awareness about it among the general public. CONCLUSION: Introducing the concept of palliation of symptoms and ensuring quality of life of the child with DMD by accessing the available services can aid the parents to reach out for help for their child.

Chitotriosidase, a biomarker of amyotrophic lateral sclerosis, accentuates neurodegeneration in spinal motor neurons through neuroinflammation.

BACKGROUND: Cerebrospinal fluid from amyotrophic lateral sclerosis patients (ALS-CSF) induces neurodegenerative changes in motor neurons and gliosis in sporadic ALS models. Search for identification of toxic factor(s) in CSF revealed an enhancement in the level and enzyme activity of chitotriosidase (CHIT-1). Here, we have investigated its upregulation in a large cohort of samples and more importantly its role in ALS pathogenesis in a rat model. METHODS: CHIT-1 level in CSF samples from ALS (n = 158), non-ALS (n = 12) and normal (n = 48) subjects were measured using ELISA. Enzyme activity was also assessed (ALS, n = 56; non-ALS, n = 10 and normal-CSF, n = 45). Recombinant CHIT-1 was intrathecally injected into Wistar rat neonates. Lumbar spinal cord sections were stained for Iba1, glial fibrillary acidic protein and choline acetyl transferase to identify microglia, astrocytes and motor neurons respectively after 48 h of injection. Levels of tumour necrosis factor-α and interleukin-6 were measured by ELISA. FINDINGS: CHIT-1 level in ALS-CSF samples was increased by 20-fold and it can distinguish ALS patients with a sensitivity of 87% and specificity of 83.3% at a cut off level of 1405.43 pg/ml. Enzyme activity of CHIT-1 was also 15-fold higher in ALS-CSF and has a sensitivity of 80.4% and specificity of 80% at cut off value of 0.1077989 µmol/µl/min. Combining CHIT-1 level and activity together gave a positive predictive value of 97.78% and negative predictive value of 100%. Administration of CHIT-1 increased microglial numbers and astrogliosis in the ventral horn with a concomitant increase in the levels of pro-inflammatory cytokines. Amoeboid-shaped microglial and astroglial cells were also present around the central canal. CHIT-1 administration also resulted in the reduction of motor neurons. CONCLUSIONS: CHIT-1, an early diagnostic biomarker of sporadic ALS, activates glia priming them to attain a toxic phenotype resulting in neuroinflammation leading to motor neuronal death.

Lived Experience of Spouses of Persons with Motor Neuron Disease: Preliminary Findings through Interpretative Phenomenological Analysis.

INTRODUCTION: Motor neuron disease (MND) is a progressive neuromuscular disorder that can have significant and debilitating impact on the affected patient and families. Spouses are the primary carers for persons with MND in India, and the life of the person with MND and their spouse is never the same after the diagnosis. AIM: The objective was to explore the lived experience of spouses of persons diagnosed with MND. METHODS: A qualitative exploratory study with three-point interviews was conducted with spouse caregivers of two persons diagnosed with MND who were receiving treatment from a national tertiary referral care center for neurological disorders. All the patients were diagnosed as definite MND according to the modified El Escorial criteria. With the spouses, in-depth interviews were conducted at their home, lasting on an average of 1 hour using a semi-structured interview guide (prompts). Interpretative phenomenological analysis was used to derive themes from the interviews. RESULTS: The major themes emerged from the analysis were meaning of MND which contained the subthemes of delay in diagnosis and deterioration, psychological response across illness trajectory, relationship with the subthemes of changing roles in being acarer, marital relationship, to be seen as doing "right," and communication; adaptation with the subthemes of coping strategies and support system and life without the loved one. CONCLUSION: The changes in the lives of spouses and in strategies for caring the partner with deterioration of symptoms in the illness trajectory are explained in this study. The palliative approach in the management of MND has to take into account, the experiences and needs of carers since care happens at home.

Increasing phenotypic annotation improves the diagnostic rate of exome sequencing in a rare neuromuscular disorder.

Phenotype-based filtering and prioritization contribute to the interpretation of genetic variants detected in exome sequencing. However, it is currently unclear how extensive this phenotypic annotation should be. In this study, we compare methods for incorporating phenotype into the interpretation process and assess the extent to which phenotypic annotation aids prioritization of the correct variant. Using a cohort of 29 patients with congenital myasthenic syndromes with causative variants in known or newly discovered disease genes, exome data and the Human Phenotype Ontology (HPO)-coded phenotypic profiles, we show that gene-list filters created from phenotypic annotations perform similarly to curated disease-gene virtual panels. We use Exomiser, a prioritization tool incorporating phenotypic comparisons, to rank candidate variants while varying phenotypic annotation. Analyzing 3,712 combinations, we show that increasing phenotypic annotation improved prioritization of the causative variant, from 62% ranked first on variant alone to 90% with seven HPO annotations. We conclude that any HPO-based phenotypic annotation aids variant discovery and that annotation with over five terms is recommended in our context. Although focused on a constrained cohort, this provides real-world validation of the utility of phenotypic annotation for variant prioritization. Further research is needed to extend this concept to other diseases and more diverse cohorts.

Family Caregivers' Experiences with Dying and Bereavement of Individuals with Motor Neuron Disease in India.

Motor neuron disease (MND) is a progressive neurodegenerative disease. Ideal management plan in MND includes palliative care initiated from the time of diagnosis. At present, most of the neurodegenerative conditions are cared for at home. Neuropalliative care is an emerging concept in India and social workers are integral team members in this process. The primary aims of the study were to explore (a) the caregivers' experiences of the end-of-life stage, and (b) the sources of support for individuals and their caregivers with MND at the end-of-life stage. In-depth interviews were conducted with seven bereaved caregivers of individuals with MND from a national tertiary referral care center for neuropsychiatry in South India. Interviews were conducted either in person or by telephone. Thematic analysis was done using the constant comparative method. Major themes derived from the interviews were: (1) Transition from person to patient, (2) support, (3) death, and (4) impact on the caregivers. Mapping of themes identified "Support received during advanced stages" as the central theme influencing all other themes. The need for a care manager seems evident and is a role that can be effectively fulfilled by the care teams' social workers.