DNA-Diagnostik bei Friedreich'scher Ataxie

Friedreich's ataxia (FRDA) is a severe progressive neurodegenerative disorder, involving both the central and peripheral nervous systems. The incidence of this autosomal recessively inherited disease is approximately 1 to 2 per 100000. The disorder is usually manifested around puberty and is generally characterised by spinal and cerebellar ataxia, dysarthria, loss of tendon reflexes, muscle weakness and disturbances of vibration and position senses. The differentiation of Friedreich's ataxia from other spinocerebellar ataxias is very difficult because of its variable expression. Localisation of FRDA locus to chromosome 9 and identification of tightly linked DNA markers make it possible to provide DNA diagnosis to families at risk. We present the DNA diagnosis data of three families, using Southern blot analysis and polymerase chain reaction. In two families with consanguineous parents the differentiation between heterozygous and homozygous non-affected offsprings was possible. DNA diagnosis of the third family with two affected children turned out to be non-informative for the linked markers. The recombination frequency between the used markers and the FRDA allele is about 1%. Hence, the risk calculation for informative families can be assumed to be reliable.