Novel insights into the genetic profile of hereditary spastic paraplegia in India.

The Hereditary Spastic Paraplegias (HSPs) are a group of clinically and genetically heterogeneous disorders characterized by length dependent degeneration of the corticospinal tracts. Genetic data related to HSPs are limited from India. We aimed to comprehensively analyse the phenotypic characteristics and genetic basis of a large cohort of HSP from India. Patients with HSP phenotype were evaluated for their clinical features, electrophysiological and radiological abnormalities. Genetic analyses were carried out by clinical exome sequencing (n = 52) and targeted sequencing (n = 5). The cohort comprised of 57 probands (M:F 40:17, age: 3.5-49 years). Based on the phenotype, the cohort could be categorized as 'pure' (n = 15, 26.3%) and 'complicated' (n = 42, 73.7%) HSP. Brain MRI showed thin corpus callosum (n = 10), periventricular hyperintensities (n = 20), cerebral atrophy (n = 3), cerebellar atrophy (n = 3) and diffuse atrophy (n = 4). Sixty-seven variants representing 40 genes were identified including 47 novel variants. Forty-eight patients (84.2%) had variants in genes previously implicated in HSP and other spastic paraplegia syndromes (SPG genes = 24, non-SPG genes = 24); among these 13 had variations in more than one gene and 12 patients (21.0%) had variations in genes implicated in potentially treatable/modifiable metabolic disorders (MTHFR = 8, MTRR = 1, ARG1 = 2 and ABCD1 = 1). In nine patients, no genetic variants implicated in spastic paraplegia phenotype were identified. Thus, the present study from India highlights the phenotypic complexities and spectrum of genetic variations in patients with HSP including those implicated in metabolically modifiable disorders. It sets a platform for carrying out functional studies to validate the causal role of the novel variants and variants of uncertain significance.

Leukodystrophy Due to eIF2B Mutations in Adults.

Vanishing white matter disease (VWMD) due to eIF2B mutations is a common leukodystrophy characterised by childhood onset, autosomal recessive inheritance, and progressive clinical course with episodic worsening. There are no reports of genetically confirmed adult patients from India. We describe the phenotype of two adults with genetically confirmed VWMD and typical radiological findings. Both had spastic ataxia and cognitive and behavioural disturbances. Other neurological features included myoclonic jerks and parkinsonism. At the last follow-up (duration: 2-9 years), one patient was wheelchair-bound. VWMD is rare in adults but should be suspected based on radiological findings and confirmed by eIF2B mutation.

Cerebral small vessel disease with hemorrhagic stroke related to COL4A1 mutation: A case report.

Stroke is a major cause of mortality and morbidity with a wide variety of etiological risk factors. Cerebral small vessel disease (SVD) is an important cause of stroke in the young with several hereditary disorders affecting these small blood vessels. Mutations in the COL4A1 gene (COL4A1) have been shown to be associated with a broad range of disorders including hemorrhagic stroke, myopathy, glaucoma and others. We report a rare case of stroke in an intellectually disabled 18-year-old girl with radiological evidence of basal ganglia microbleeds, periventricular white matter signal changes and porencephalic cyst. Ophthalmic examination revealed bilateral microcornea and Axenfeld-Rieger anomaly. At autopsy there were hemorrhagic lesions at multiple sites within the brain. Histology revealed thickened small-caliber vessels which demonstrated disruption and fragmentation of the basement membrane by collagen type IV alpha 1 immunohistochemistry and by electron microscopy. A missense COL4A1 mutation involving glycine residue was detected in the patient. The present case illustrates the clinicopathological spectrum of COL4A1-related cerebral SVD presenting as hemorrhagic stroke in the young with porencephaly, intellectual disability, and Axenfield-Rieger anomaly and thus adds to the clinical heterogeneity of this genetic disorder.

Mitochondrial dysfunction in human skeletal muscle biopsies of lipid storage disorder.

Mitochondria regulate the balance between lipid metabolism and storage in the skeletal muscle. Altered lipid transport, metabolism and storage influence the bioenergetics, redox status and insulin signalling, contributing to cardiac and neurological diseases. Lipid storage disorders (LSDs) are neurological disorders which entail intramuscular lipid accumulation and impaired mitochondrial bioenergetics in the skeletal muscle causing progressive myopathy with muscle weakness. However, the mitochondrial changes including molecular events associated with impaired lipid storage have not been completely understood in the human skeletal muscle. We carried out morphological and biochemical analysis of mitochondrial function in muscle biopsies of human subjects with LSDs (n = 7), compared to controls (n = 10). Routine histology, enzyme histochemistry and ultrastructural analysis indicated altered muscle cell morphology and mitochondrial structure. Protein profiling of the muscle mitochondria from LSD samples (n = 5) (vs. control, n = 5) by high-throughput mass spectrometric analysis revealed that impaired metabolic processes could contribute to mitochondrial dysfunction and ensuing myopathy in LSDs. We propose that impaired fatty acid and respiratory metabolism along with increased membrane permeability, elevated lipolysis and altered cristae entail mitochondrial dysfunction in LSDs. Some of these mechanisms were unique to LSD apart from others that were common to dystrophic and inflammatory muscle pathologies. Many differentially regulated mitochondrial proteins in LSD are linked with other human diseases, indicating that mitochondrial protection via targeted drugs could be a treatment modality in LSD and related metabolic diseases. Cover Image for this Issue: doi: 10.1111/jnc.14177.

Comprehensive cytokine profiling provides evidence for a multi-lineage Th responses in Guillain Barré Syndrome.

Guillain Barré Syndrome (GBS) is one of the commonest acquired immune-mediated neuropathies, often preceded by infections. Although cellular immune responses are shown to substantially account for the pathophysiology of GBS, the precise mechanistic basis of risk and disease course remains enigmatic till date. Cytokines are best known for their abilities to drive cellular immunity and inflammation through their co-ordinated actions. Data obtained from clinical and animal model studies suggest important implications of some of the cytokines in the progression and recovery of GBS. However, these studies were performed on few cytokines and small set of GBS patients, thereby lacking a complete understanding of the patterns of association of cytokines representing Th1, Th2, and Th17 responses with GBS. We studied 65 well-characterized GBS patients and 73 age- and sex-matched healthy controls. A panel of 15 cytokines representing Th1, Th2 and Th17 pathways was assayed using Multiplex Suspension Array platform. Plasma levels of five cytokines were found to be altered in GBS patients compared to healthy control subjects: (i) IL-1ß exhibited reduced levels, and (ii) IFN-γ, IL-4, IL-21 and IL-33 were elevated in GBS patients. The most important finding of this study was up-regulated expression of IL-21 and IL-33 in patients with GBS. Given the role of IL-33 as an alarmin, the elevated level of this cytokine provides important indication about a much broader role of cytokines in GBS. This study also provides evidence towards a multi-lineage Th cells (Th1, Th2 and Th17) associated cytokine responses in the pathophysiology of GBS.

Novel magnetic resonance imaging findings in a patient with short chain acyl CoA dehydrogenase deficiency.

Reports on magnetic resonance imaging findings in patients with short chain acyl -Coenzyme A dehydrogenase (SCAD) deficiency, an autosomal recessive disorder caused by mutations in the acyl-Coenzyme A dehydrogenase (ACADS), are limited. Many asymptomatic carriers of ACAD variants have also been described necessitating careful evaluation of clinical and biochemical findings for an accurate diagnosis. Here we report a an infant with short chain acyl -Coenzyme A dehydrogenase (SCAD) deficiency diagnosed based on the characteristic biochemical findings and confirmed by genetic testing. He presented with refractory seizures and neuro regression at 4 months of age. His metabolic work up revealed elevated butyryl carnitine in plasma and ethyl malonic acid in urine. Magnetic resonance imaging of the brain showed cortical and basal ganglia signal changes with cortical swelling. Serial scans showed progression of the lesions resulting in cystic leukomalacia with brain atrophy. Exome sequencing revealed a novel homozygous nonsense variation, c.1146C > G (p.Y382Ter) in exon ten of ACADS which was further validated by Sanger sequencing. Both parents were heterozygous carriers. Follow up at 15 months showed gross psychomotor retardation and refractory seizures despite being on optimal doses of anti-epileptic medications, carnitine and multivitamin supplementation. This report expands the phenotypic and genotypic spectrum of SCAD deficiency.

Clinical Features, Therapeutic Response, and Follow-Up in Pediatric Anti-N-Methyl-D-Aspartate Receptor Encephalitis: Experience from a Tertiary Care University Hospital in India.

AIM: To describe the clinical features in pediatric anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis with specific reference to the spectrum of involuntary movements, and therapeutic response to pulsed intravenous methyl prednisolone. METHOD: A total of 13 children with anti-NMDAR antibody positivity were evaluated. RESULTS: Abnormal behavior, global regression, and seizures were universal. Movement disorder was characterized by hyperkinetic large amplitude, complex, multidirectional movements involving the limbs and orofacial musculature. Electroencephalogram was abnormal in all during the acute phase. All received intravenous methyl prednisolone. Plasmapheresis (n = 6) and intravenous immunoglobulin (n = 2) were administered due to subtherapeutic response during the acute illness. Monthly pulsed methyl prednisolone was administered to maintain remission. All improved substantially from the acute illness which was reflected in the modified Rankin score. Ten patients were followed up for a median duration of 10.30 ± 6.7 months. Residual symptoms included hypersomnolence, hyperphagia, hyperactivity, overfamiliarity, among others. Three had recurrence of partial syndrome that was related to delay in pulsed methyl prednisolone therapy. They improved and maintained improvement with reinitiation of pulsed methyl prednisolone therapy. CONCLUSION: Anti-NMDAR encephalitis requires prolonged immunomodulatory therapy. Intravenous pulsed methyl prednisolone therapy is beneficial in inducing and maintaining remission. It is safe, effective, and well tolerated by children with anti-NMDAR encephalitis. The duration of treatment required for sustained remission and cure needs to be determined in long-term studies.

Huppke-Brendel syndrome in a seven months old boy with a novel 2-bp deletion in SLC33A1.

Huppke -Brendel syndrome is a new addition to the evolving spectrum of copper metabolism defects. It is an autosomal recessive disorder characterized by congenital cataract, impaired hearing, and developmental delay with low copper and ceruloplasmin. It is caused by defects in SLC33A1 that codes for acetyl CoA transporter protein. Reports on variation in this gene causing human disease is extremely scarce and the metabolic link between this gene and copper metabolism is yet to be identified. Here we report a seven months old infant with Huppke-Brendel Syndrome. In addition to the already reported features, he also had hypo pigmented hair and hypogonadism. His magnetic resonance imaging revealed hypo myelination and cerebellar hypoplasia. Clinical exome sequencing revealed a homozygous two base pair deletion, c.542_543delTG (p.Val181GlyfsTer6) in exon 1 of the SLC33A1. This report expands the phenotypic and genotypic spectrum of Huppke Brendel syndrome.

Genetic analysis of an Indian family with members affected with Waardenburg syndrome and Duchenne muscular dystrophy.

PURPOSE: Waardenburg syndrome (WS) is characterized by sensorineural hearing loss and pigmentation defects of the eye, skin, and hair. It is caused by mutations in one of the following genes: PAX3 (paired box 3), MITF (microphthalmia-associated transcription factor), EDNRB (endothelin receptor type B), EDN3 (endothelin 3), SNAI2 (snail homolog 2, Drosophila) and SOX10 (SRY-box containing gene 10). Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations in the DMD gene. The purpose of this study was to identify the genetic causes of WS and DMD in an Indian family with two patients: one affected with WS and DMD, and another one affected with only WS. METHODS: Blood samples were collected from individuals for genomic DNA isolation. To determine the linkage of this family to the eight known WS loci, microsatellite markers were selected from the candidate regions and used to genotype the family. Exon-specific intronic primers for EDN3 were used to amplify and sequence DNA samples from affected individuals to detect mutations. A mutation in DMD was identified by multiplex PCR and multiplex ligation-dependent probe amplification method using exon-specific probes. RESULTS: Pedigree analysis suggested segregation of WS as an autosomal recessive trait in the family. Haplotype analysis suggested linkage of the family to the WS4B (EDN3) locus. DNA sequencing identified a novel missense mutation p.T98M in EDN3. A deletion mutation was identified in DMD. CONCLUSIONS: This study reports a novel missense mutation in EDN3 and a deletion mutation in DMD in the same Indian family. The present study will be helpful in genetic diagnosis of this family and increases the mutation spectrum of EDN3.

Sjogren-Larsson Syndrome: Mechanisms and Management.

Sjogren Larsson syndrome (SLS) is a rare autosomal recessive inborn error of lipid metabolism due to mutations in the ALDH3A2 that result in a deficiency of fatty aldehyde dehydrogenase (FALDH). The syndrome has a high prevalence in Sweden where it was first described, but now known to occur worldwide. The classical triad of ichthyosis, mental retardation and spasticity characterizes clinical features. Preterm birth is common. "Glistening white dots" in the retina is a pathognomic clinical feature. Magnetic resonance imaging of the brain demonstrates leukoencephalopathy predominant in the periventricular region. Cerebral MR spectroscopy reveals a characteristic abnormal lipid peak at 1.3ppm and a small peak at 0.9ppm. The primary role of FALDH is oxidation of medium and long-chain aliphatic aldehydes derived from fatty alcohol, phytanic acid, ether glycerolipids and sphingolipids. The diagnosis is based on the typical phenotype, demonstration of the enzyme deficiency and presence of biallelic mutations in the ALDH3A2. The management of SLS largely remains symptomatic currently. However, several potential therapeutic options are being developed, keeping in view of the fundamental metabolic defects or correcting the genetic defect. This review aims to summarize the clinical, genetic and biochemical findings, pathogenetic mechanisms and the current therapeutic options, in SLS.

Variable treatment response in a patient with pyridoxal N phosphate oxidase (PNPO) deficiency- understanding the paradox.

A 6-year-old girl presented with history of infantile onset epileptic encephalopathy and developmental delay. She had polymorphic seizures that were refractory to regular anti-seizure medication. Incomplete control of seizures was achieved on starting pyridoxine, riboflavin and thiamine. Clinical exome sequencing done at 4 years revealed PNPO deficiency with a homozygous mutation in the highly conserved exon 3:c.352G > A p.Gly118R region of the gene. Thereafter, pyridoxine was weaned and pyridoxal phosphate was added with resultant refractory status epilepticus, which necessitated our approach to start pyridoxine and stop pyridoxal phosphate. With two antiseizure medication and three vitamins, she had improved seizure control. At 6 years of age an attempt to wean off riboflavin resulted in break through seizures. After restarting riboflavin along with pyridoxal phosphate, pyridoxine in low doses and two antiseizure medications, the child achieved good seizure control. Though partial responsiveness to pyridoxine with gene mutation in the exon 3: c.352G > A p. Gly118R is known, riboflavin dependence and transient worsening of seizures off pyridoxine has not been described to our knowledge. Our case highlights the importance of identifying the precise gene mutationsequence to properly identify variants relative to individual phenotypic expression, treatment responsivness and need for added vitamin supplementation.

Evidence of altered Th17 pathway signatures in the cerebrospinal fluid of patients with Guillain Barré Syndrome.

Data indexing the contribution of various immuno-inflammatory components in the cerebrospinal fluid (CSF) towards the pathophysiology of Guillain Barré Syndrome (GBS) are limited. Th17 pathway plays crucial role in many immune mediated disorders of the nervous system. This study was aimed at exploring the role of Th17 pathway related cytokines in the CSF of patients with GBS. Levels of multiple key cytokines of Th17 pathway in CSF of patients with GBS (N = 37) and controls (N = 37) were examined in this prospective study using Bio-plex Pro Human Th17 cytokine assays in a Multiplex Suspension Array platform. The findings were correlated with clinical features and electrophysiological subtypes. Three key cytokines of Th17 pathway (IL-6, IL-17A and IL-22) were significantly elevated in CSF of patients with GBS as compared to controls. There was a positive correlation between the levels of IL-6 and IL-17A as well as between the levels of IL-17A and IL-22 in the CSF of patients with GBS. The CSF levels of IL-6 and IL-22 were negatively correlated with the duration of symptoms of GBS. None of the studied cytokines correlated with functional disability scores at admission to hospital or with the electrophysiological subtypes. Identification of Th17 pathway signatures in CSF sheds more insights into the pathogenic role of Th17 cells in GBS. These findings complement the contemporary knowledge and tender further support towards the involvement of Th17 pathway in GBS.

Genetically Established Familial Amyloidotic Polyneuropathy from India: Narrating the Diagnostic "Odyssey" and a Mini Review.

CONTEXT: Familial amyloidotic polyneuropathy (FAP) is often misdiagnosed as other neuropathic illnesses. AIM: To highlight the diagnostic "odyssey" in three families of Indian origin with FAP. SETTINGS AND DESIGN: Cross-sectional, hospital-based study. SUBJECTS AND METHODS: Clinical, radiological, and histological features as well as causes for delayed diagnosis were analyzed in genetically confirmed patients with FAP. STATISTICAL ANALYSIS: Descriptive. RESULTS: Age at evaluation ranged from 24 to 42 years and symptom duration from 1 to 10 years. Referral diagnoses included: (i) in patients 1 and 2-familial dysautonomia, Shy-Drager syndrome, and spino-cerebellar ataxia with seizures, (ii) in patient 3-chronic inflammatory demyelinating polyradiculoneuropathy, and (iii) in patient 4-porphyria. In addition, patients 1 and 2 developed leptomeningeal involvement that was mistaken for tubercular meningitis. Reasons for missed diagnosis included: clinician's lack of awareness, not paying sufficient attention to family history, presence of laboratory distractors such as elevated urinary porphyrins, lack of meticulous search for amyloid in the biopsy, and not performing specific stain for amyloid viz. Congo red. Evidence of amyloid in histological studies of nerve and skin supported by genetic variations in transthyretin gene clinched the diagnosis. The variants identified in our cohort included p.Gly73Glu, p.Val71Ala, and p.Val50Met. CONCLUSION: Lack of awareness and meticulous work-up by clinicians and pathologists contributed to delayed diagnosis of FAP. It is important to establish an accurate diagnosis as these patients may be candidates for upcoming therapies.

Comparing the efficacy of sodium valproate and levetiracetam following initial lorazepam in elderly patients with generalized convulsive status epilepticus (GCSE): A prospective randomized controlled pilot study.

PURPOSE: This randomized control study was conducted to compare the efficacy of sodium valproate (SVP) and levetiracetam (LEV) following initial intravenous lorazepam in elderly patients (age: >60years) with generalized convulsive status epilepticus (GCSE) and to identify predictors of poor seizure control. METHODS: A total of 118 patients (mean age: 67.5 ± 7.5 years, M:F = 1.6:1), who had presented with GCSE were randomized into the SVP or LEV treatment arms. All patients received initial intravenous lorazepam (0.1 mg/kg) followed by one of the two antiepileptic drugs (AEDs), parenteral SVP (20-25 mg/kg) or LEV (20-25 mg/kg). Those who failed to achieve control with the initial AED, were crossed over to receive the other AED. One-hundred patients (SVP = 50; LEV = 50) completed the study. RESULTS: SE could be controlled with lorazepam and one of the AEDs (SVP or LEV) in 71.18% (84/118). Intention-to-treat analysis showed that the two groups did not differ significantly in terms of seizure control [SVP: 41/60 (68.3%); LEV: 43/58 (74.1%), p = 0.486]. Of 100 patients who completed the study, seizure control was achieved in 38/50(76%) in the SVP and 43/50(86%) in the LEV group (p = 0.202). After crossing over to the second AED, SE could be controlled in an additional in 50% (6/12) in SVP (+LEV) group and in 14.3% (1/7) in LEV (+SVP) group. Overall, after the second AED, seizure control was achieved in 77.1% (91/118). Higher STESS was associated with poor therapeutic response (p = 0.049). CONCLUSIONS: The efficacy of SVP and LEV following initial lorazepam in controlling GCSE in elderly population was comparable, hence the choice of AED could be individualized.

Exome sequencing in adult neurology practice: Challenges and rewards in a mixed resource setting.

OBJECTIVE: To share the experience of next-generation sequencing (NGS) in delineating molecular basis of neuro-genetic disorders in adults of Indian origin. PATIENTS AND METHODS: Adults (aged ≥18 years) evaluated in a single neurology unit at a tertiary-care teaching hospital between August 2014 and September 2016, underwent NGS for (i) sporadic occurrence of neurological disorder where an extensive search did not reveal an acquired cause or (ii) familial or sporadic, uncommon, seemingly genetic disorder where single monogenic cause could not be ascertained based on phenotype. Presence of pathogenic/ likely-pathogenic variants, novel genetic variants, and novel phenotype associations were noted. RESULTS: Clinical phenotypes included: neuromuscular (n = 14), extrapyramidal (n = 8), ataxia (n = 7), leukoencephalopathy (n = 6), spastic paraplegia (n = 5), stroke (n = 4), progressive myoclonic epilepsy (n = 1) and epilepsy with developmental delay (n = 1). Fifty-eight variants were identified in 43 genes in 34 patients, that included 15 (25.9%) reported variants. Genetic diagnosis could be established in 14 (30.43%) subjects. Six probands (13%) harboured previously unreported variants in a clinically relevant gene. Nine probands harboured unreported variants in two or more different genes associated with the clinical phenotype. In three probands we noted novel associations between the phenotype and genetic variation. In all patients, genetic diagnosis impacted treatment and prognostication. CONCLUSIONS: We present data of NGS in adults with suspected neuro-genetic disorders from India and this is the first report of its kind. It sets a platform for further basic science research to validate 'novel' variants and those of 'uncertain significance' as pathogenic or otherwise with specific reference to Indian ethnicity.

Mitochondrial leukoencephalopathies: A border zone between acquired and inherited white matter disorders in children?

BACKGROUND: There is emerging evidence implicating mitochondrial dysfunction in the pathogenesis of acquired demyelinating disorders such as multiple sclerosis. On the other hand, some of the primary mitochondrial disorders such as mitochondrial leukoencephalopathies exhibit evidence of neuroinflammation on MRI. The inter-relationship between mitochondrial disorders and episodic CNS inflammation needs exploration because of the therapeutic implications. OBJECTIVE: We sought to analyze the clinical course and MRI characteristics in a cohort of patients with mitochondrial leukoencephalopathy to determine features, if any, that mimic primary demyelinating disorders. Therapeutic implications of these findings are discussed. PATIENTS AND METHODS: Detailed analysis of the clinical course, magnetic resonance imaging findings and therapeutic response was performed in 14 patients with mitochondrial leukoencephalopathy. The diagnosis was ascertained by clinical features, histopathology, respiratory chain enzyme assays and exome sequencing. RESULTS: Fourteen patients [Age at evaluation: 2-7 yrs, M: F-1:1] were included in the study. The genetic findings included variations in NDUFA1 (1); NDUFV1 (4); NDUFS2 (2); LYRM (2);MPV17(1); BOLA3(2); IBA57(2). Clinical Features which mimicked acquired demyelinating disorder included acute onset focal deficits associated with encephalopathy [10/14, 71%], febrile illness preceding the onset [7/14, 50%] unequivocal partial or complete steroid responsiveness [11/11], episodic/ relapsing remitting neurological dysfunction [10/14, 71%] and a subsequent stable rather than a progressive course [12/14, 85%]. MRI characteristics included confluent white matter lesions [14/14, 100%], diffusion restriction [11/14,78.5%], contrast enhancement [13/13,100%], spinal cord involvement [8/13,61.5%], lactate peak on MRS [13/13] and white matter cysts [13/14, 92.8%]. CONCLUSION: Clinical presentations of mitochondrial leukoencephalopathy often mimic an acquired demyelinating disorder. The therapeutic implications of these observations require further exploration.

Th17 pathway signatures in a large Indian cohort of Guillain Barré syndrome.

The etiopathogenesis of Guillain Barré Syndrome (GBS) is inadequately understood. The role of immuno-inflammatory Th17 pathway was examined in GBS patients by genetic, gene expression and biochemical studies. Genotyping of G197A single nucleotide polymorphism within IL17 gene was carried out by PCR-RFLP method in 220 GBS patients. Quantification of gene expression of STAT3 and RORC and estimation of plasma level of IL-17A were carried out in a subset of patients. Significantly increased STAT3 gene expression in lymphocytes and plasma IL-17A levels were observed in GBS patients. This study adds new dimension and reinforces important implications of Th17 pathway in GBS.

Outcome of epilepsy in patients with mitochondrial disorders: Phenotype genotype and magnetic resonance imaging correlations.

OBJECTIVES: Studies exploring the outcome of epilepsy in patients with mitochondrial disorders are limited. This study examined the outcome of epilepsy in patients with mitochondrial disorders and its relation with the clinical phenotype, genotype and magnetic resonance imaging findings. PATIENTS AND METHODS: The cohort was derived from the database of 67 patients with definite genetic diagnosis of mitochondrial disorders evaluated over a period of 11years (2006-2016). Among this, 27 had epilepsy and were included in final analysis. Data were analyzed with special reference to clinical phenotypes, genotypes, epilepsy characteristics, EEG findings, anti epileptic drugs used, therapeutic response, and magnetic resonance imaging findings. Patients were divided into three groups according to the seizure frequency at the time of last follow up: Group I- Seizure free; Group II- Infrequent seizures; Group III- uncontrolled seizures. For each group the clinical phenotype, genotype, magnetic resonance imaging and duration of epilepsy were compared. RESULTS: The phenotypes & genotypes included Mitochondrial Encephalopathy Lactic Acidosis and Stroke like episodes (MELAS) & m.3243A>G mutation (n = 10), Myoclonic Epilepsy Ragged Red Fiber syndrome (MERRF) & m.8344A>G mutation (n = 4), Chronic Progressive External Ophthalmoplegia plus &POLG1 mutation (CPEO, n = 6), episodic neuroregression due to nuclear mutations (n = 6; NDUFV1 (n = 3), NDUFA1, NDUFS2, MPV17-1 one each), and one patient with infantile basal ganglia stroke syndrome, mineralizing angiopathy &MT-ND5 mutations. Seven patients (25.9%) were seizure free; seven had infrequent seizures (25.9%), while thirteen (48.1%) had frequent uncontrolled seizures. Majority of the subjects in seizure free group had episodic neuroregression & leukoencephalopathy due to nuclear mutations (85.7%). Patients in group II with infrequent seizures had CPEO, POLG1 mutation and a normal MRI (71%) while 62% of the subjects in group III had MELAS, m.3243A>G mutation and stroke like lesions on MRI. CONCLUSIONS: A fair correlation exists between the outcome of epilepsy, clinical phenotypes, genotypes and magnetic resonance imaging findings in patients with mitochondrial disorders. The recognition of these patterns is important clinically because of the therapeutic and prognostic implications.