title: Peripheral neuropathy in genetically characterized patients with mitochondrial disorders: A study from south India.
abstract: BACKGROUND
  There are relatively few studies, which focus on peripheral neuropathy in large cohorts of genetically characterized patients with mitochondrial disorders. This study sought to analyze the pattern of peripheral neuropathy in a cohort of patients with mitochondrial disorders.
  
  
  METHODS
  The study subjects were derived from a cohort of 52 patients with a genetic diagnosis of mitochondrial disorders seen over a period of 8 years (2006-2013). All patients underwent nerve conduction studies and those patients with abnormalities suggestive of peripheral neuropathy were included in the study. Their phenotypic features, genotype, pattern of peripheral neuropathy and nerve conduction abnormalities were analyzed retrospectively.
  
  
  RESULTS
  The study cohort included 18 patients (age range: 18 months-50 years, M:F- 1.2:1).The genotype included mitochondrial DNA point mutations (n=11), SURF1 mutations (n=4) and POLG1(n=3). Axonal neuropathy was noted in 12 patients (sensori-motor:n=4; sensory:n=4; motor:n=4) and demyelinating neuropathy in 6. Phenotype-genotype correlations revealed predominant axonal neuropathy in mtDNA point mutations and demyelinating neuropathy in SURF1. Patients with POLG related disorders had both sensory ataxic neuropathy and axonal neuropathy.
  
  
  CONCLUSIONS
  A careful analysis of the family history, clinical presentation, biochemical, histochemical and structural analysis may help to bring out the mitochondrial etiology in patients with peripheral neuropathy and may facilitate targeted gene testing. Presence of demyelinating neuropathy in Leigh's syndrome may suggest underlying SURF1 mutations. Sensory ataxic neuropathy with other mitochondrial signatures should raise the possibility of POLG related disorder.
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: drpsbindu@yahoo.co.in.
authors.forename: Parayil Sankaran
authors.initials: PS
authors.lastname: Bindu
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: drgobiraj76@yahoo.com.
authors.forename: Chikanna
authors.initials: C
authors.lastname: Govindaraju
authors.affiliation: Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: sonamkothari86@yahoo.com.
authors.forename: Kothari
authors.initials: K
authors.lastname: Sonam
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: madhu_nagappa@yahoo.co.in.
authors.forename: Madhu
authors.initials: M
authors.lastname: Nagappa
authors.affiliation: Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: shwetha.chiplunkar@gmail.com.
authors.forename: Shwetha
authors.initials: S
authors.lastname: Chiplunkar
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: rockyroyal1999@gmail.com.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: gayathrin12@rediffmail.com.
authors.forename: Narayanappa
authors.initials: N
authors.lastname: Gayathri
authors.affiliation: Department of Neurochemistry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: thathachar@rediffmail.com.
authors.forename: M M Srinivas
authors.initials: MM
authors.lastname: Bharath
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
authors.forename: Hanumanthapura R
authors.initials: HR
authors.lastname: Arvinda
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: sanjib_sinha2004@yahoo.co.in.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Sinha
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: nahid.ibu@gmail.com.
authors.forename: Nahid Akthar
authors.initials: NA
authors.lastname: Khan
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: pgovinth@gmail.com.
authors.forename: Periyasamy
authors.initials: P
authors.lastname: Govindaraj
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: vandananunia@gmail.com.
authors.forename: Vandana
authors.initials: V
authors.lastname: Nunia
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: paramasivam@ccmb.res.in.
authors.forename: Arumugam
authors.initials: A
authors.lastname: Paramasivam
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: thangs@ccmb.res.in.
authors.forename: Kumarasamy
authors.initials: K
authors.lastname: Thangaraj
authors.affiliation: Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: abtaly@yahoo.com.
authors.forename: Arun B
authors.initials: AB
authors.lastname: Taly
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007194:India; D007223:Infant; D008297:Male; D008875:Middle Aged; D028361:Mitochondrial Diseases / Q000150:complications* / Q000235:genetics*; D009431:Neural Conduction; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D012189:Retrospective Studies; D055815:Young Adult
keywords: Mitochondrial neuropathy; POLG1; Peripheral neuropathy; SURF1; and MTATP6