Novel Homozygous MPV-17 Mutation Resulting in Mitochondrial Depletion Syndrome (MDS) Presenting as Peripheral Neuropathy, Leukoencephalopathy, Chronic Liver Disease and Pancreatitis
Jayaram S1, Pradeep P Nair2, Vaibhav Wadwekar3
1Neurology, JIPMER, Pondicherry, 2Neurology, JIPMER, 3Neurology, Jawaharlal Institute of Postgraduate Medical Education & Research (JIPMER)
Objective:
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Background:
Mitochondrial DNA (mtDNA) depletion syndromes (MDS) are severe autosomal recessive disorders associated with decreased mtDNA copy number in clinically affected tissues.  Here, we report a unique case of novel homozygous mutation of MPV-17 which presented as progressive axonal sensorimotor peripheral neuropathy, pancreatitis, liver dysfunction, raised serum lactate and leukoencephalopathy. 
Design/Methods:
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Results:

      A 22-year-old female, diagnosed to have pancreatitis 3 years back followed by diabetes mellitus 9 months later, developed difficulty in walking and getting up from sitting position in another 3 months’ time. She started getting imbalance while walking which increased on closing eyes for 1 year, and difficulty in gripping objects for 6 months. No one in the family has a similar illness. Examination revealed left cervical lymphadenopathy, hepatosplenomegaly, hammer toes and high stepping gait. She also had asymmetric, predominantly distal LMN areflexic quadriparesis, positive Romberg sign, impaired JPS and graded sensory loss. Initial evaluation revealed a low serum vitamin B12 levels which was supplemented; however, improvement was transient. Nerve Conduction Study showed severe axonal sensorimotor polyneuropathy. MRI brain showed T2/FLAIR hyperintense confluent lesions in left frontal & Bilateral parieto-occipital region with vasogenic edema and concentric ring enhancing lesion in right high frontal region and in dorsal column. MRS showed lactate peak. CECT abdomen showed hepatomegaly and features suggestive of Chronic liver disease & chronic pancreatitis. CSF analysis showed elevated proteins (230 mg/dl), normal cells & glucose. Serum lactate was elevated. Evaluation for MELAS, MNGIE, Balo concentric sclerosis, POEMS & SACD were negative. WES revealed MPV17 homozygous novel mutation in exon 5 (c.293C>T p. Pro98Leu) AR inheritance, suggestive of Charcot Marie Tooth Disease 2 EE. She was treated symptomatically, screening & genetic counselling of family members advised. 

Conclusions:

CMTD-2EE which is a mitochondrial depletion syndrome resulting from rare homozygous mutation in MPV-17   can present as axonal polyneuropathy, pancreatitis & hepatocerebral syndrome in 1st to 2nd decade.

10.1212/WNL.0000000000205592