distal hereditary motor neuronopathy type 2B

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distal hereditary motor neuronopathy type 2B

An autosomal recessive neuromuscular disorder (OMIM:608634) caused by selective impairment of motor neurons in the anterior horn of the spinal cord, without sensory deficit (posterior horn). It begins with weakness and wasting of distal muscles of the anterior tibial and peroneal compartments of the legs, later expanding to the proximal leg muscles and/or to the distal upper limbs.
 
Molecular pathology
Defects of HSPB1, which encodes a member of the heat shock protein 20 family, cause distal hereditary motor neuropathy 2B.
References in periodicals archive ?
Within these types, CMT type 2F (CMT2F) and distal hereditary motor neuropathy 2B (dHMN2B) are caused by heat shock 27 kDa protein 1 (HSPB1, also known as HSP27) mutation in chromosome 7q11.23 [2].
Clinically, [HSPB1.sup.P182L] is causative of dHMN2B, whereas [HSPB1.sup.S135F] is causative of both CMT2F and dHMN2B [2].
Patient-specific iPSCs were generated from one CMT2F patient (female/52-year-old, Korean) with 404C>T (S135F) mutation and one dHMN2B patient (female/8-year-old, Korean) with 545C>T (P182L) mutation of the HSPB1 gene.
In this system, specific cellular models of CMT2F and dHMN2B showed defects in mitochondrial transport, as the absolute velocity of moving mitochondria and the percentage of moving mitochondria were lower than control MNs.
Hence, defects in the axonal trafficking of mitochondria are associated with decreased acetylation of [alpha]-tubulin, which may be the main causative factor for axonopathy in CMT2F and dHMN2B.