Instituto Valenciano de Microbiología

Masía El Romeral
Ctra. de Bétera a San Antonio Km. 0.3
46117 Bétera (Valencia)
Phone. 96 169 17 02
Fax 96 169 16 37
CIF B-96337217


Sensory ataxia with epileptic myopathy -MEMSA- (Myoclonic epilepsy myopathy sensory ataxia -MEMSA-) - POLG gene.

With sensory ataxia myoclonic epilepsy myopathy (MEMSA), it is part of a group of disorders called POLG related disorders. Diseases of this group have a number of similar signs and symptoms related functions that affect the muscles, nerves and brain. This alteration had been known as spinocerebellar ataxia with epilepsy (SEEA).

Signs and symptoms usually appear MEMSA during adulthood. Usually, the first symptom of the disease is cerebellar ataxia. Later, there may be episodes of epilepsy accompanied by myoclonus. Often the attacks start in the right arm and extend throughout the body. In addition, those affected may have encephalopathy or myopathy. Myopathy may affect proximal muscles, such as the muscles of the hips, thighs, arms, or neck, or distal, such as the muscles of the hands or feet muscles. Myopathy may be especially noticeable during exercise.

This process is due to mutations in the POLG gene, located on the long arm of chromosome 15 (15q25). This gene encodes the alpha subunit, gamma protein polymerase (pol ?). The alpha subunit, binds to two copies of the beta subunit to form pol ?. Pol ? is a DNA polymerase, which "reads" DNA sequences and used as templates for encoding new DNA. These enzymes are important to copy genetic mater ial cells. Polymerases also play a critical role in DNA repair. Pol ? is the only DNA polymerase is active in the mitochondria and can copy mtDNA.

Most POLG gene mutations change the individual amino acids in the alpha subunit of pol ?, which decreases the efficiency copy of mtDNA. And other disorders related to the POLG gene, individuals with mtDNA reduction MEMSA present in affected tissues, such as muscle or brain. This reduction in mtDNA decreases the amount of energy available to the cell due to reduced oxidative phosphorylation, which may explain the signs and symptoms of MEMSA.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with sensory ataxia with myoclonus epilepsy myopathy (MEMSA), by complete PCR amplification of the exons of the POLG gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).