[Friedreich's disease: a real spectrum of clinical manifestations in terms of direct DNA diagnosis].
Friedreich's disease (FD) is autosomal-recessive form of hereditary ataxias conditioned by expansion of the trinucleotide GAA-repetitions in a new X25 gene. The study was performed in 20 patients from 13 families of different ethnic origin (Slavs, Turkmen, Moldavians, etc) with a suspicion to FD as well as in their 24 relatives who were clinically healthy. Direct DNA-diagnosis confirmed FD diagnosis in patients from 11 families; besides, a number of GAA-repetitions in the patients was in the range from 100 till 1200 (680 +/- 350). A molecular analysis revealed that FD severity was determined by a character of the mutation in each case: a classic form of the disease was characterized by the highest degree of the expansion of GAA-repetitions (more than 400), meanwhile atypic FD cases with late debut and slow progression were conditioned by either a small degree of the expansion of GAA-repetitions or by the presence of point mutations in one of the gene's alleles. A direct DNA-diagnosis permitted to determine a heterozygous carriage of the mutation in 3 clinically healthy individuals. Such cases are necessary to take into consideration in medico-genetic consultations.
Illarioshkin
S N
SN
Drizuna
E B
EB
Bagieva
G Kh
GKh
Markova
E D
ED
Miklina
N I
NI
Ovchinnikov
I V
IV
Ivanova-Smolenskaia
I A
IA
D000328:Adult; D000483:Alleles; D004252:DNA Mutational Analysis; D005621:Friedreich Ataxia / Q000175:diagnosis* / Q000235:genetics*; D015870:Gene Expression / Q000235:genetics*; D005817:Genetic Counseling; D006579:Heterozygote; D006801:Humans; D033862:Iron-Binding Proteins; D008875:Middle Aged; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D017354:Point Mutation / Q000235:genetics; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D000096923:Frataxin
D033862:Iron-Binding Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D000096923:Frataxin