Myoadenylate Deaminase Deficiency, MAD - AMPD1

Adenosine-Monophosphate-Deaminase1

Klinische Symptomatik

Recuced levels of muscle-specific myoadenylate deaminase (MAD) may cause metabolic myopathy, which manifests predominantly after muscular exercise as early signs of fatigue, cramps or muscle pain, and possibly recurrent myoglobinuria. Some patients are severely affected, whereas others are minimally affected or asymptomatic. Therefore, so far unknown factors could act as modulators of phenotype expression.

Genetik

The AMPD1 (adenosine-monophosphate-deaminase 1) gene is located on chromosome 1 (1p13-21). The molecular basis of most MAD deficiency cases in Caucasians has been attributed to a single mutant allele characterized by double C to T transitions at nucleotide positions 34 and 143 (34C>T; exon 2 and 143C>T; exon 3) of the AMPD1 gene. Heterozygosity is usually not associated with symptoms. Homozygous individuals may be asymptomatic, or suffer from exercise-induced myalgia.

Häufigkeit

Homozygous mutation: 1 : 100
Heterozygous mutation: approx. 1 : 10

 

Diagnostik