10 years' experience in fragile X testing among mentally retarded individuals in Greece: a molecular and epidemiological approach.
Fragile X syndrome, the second most common genetic cause of mental retardation, is due to the expansion of a trinucleotide repeat (CGG)n within the first exon of the FMR-1 gene. Molecular genetic analysis provides accurate diagnosis and facilitates genetic counselling and prenatal testing. Screening for the fragile X mutation in a sample of 3,888 individuals in Greece is reported: 1,755 children with non-specific mental retardation, 1,733 parents and other family members and 400 normal individuals. Molecular analysis allowed for the identification and characterization of 52 fragile X families confirming the clinical diagnosis in 57 males and 4 females. Sixty-six female carriers (6 mentally retarded) and 4 normal transmitting males were also identified. Four severely retarded males and their mothers carried unmethylated premutations, while a moderately retarded girl had a deletion of approximately equal to 150 bp. Overall sizing of the CGG repeat produced an allele distribution of 6-58 CGG repeats (mean 28-30), similar to that in other Caucasian populations.
Sofocleous
C
C
Department of Medical Genetics, Athens University School of Medicine, Athens, Greece.
Kitsiou
S
S
Fryssira
H
H
Kolialexi
A
A
Kalaitzidaki
M
M
Roma
E
E
Tsangaris
G Th
GT
Chistofidou
C
C
Metaxotou
C
C
Kanavakis
E
E
Mavrou
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D005600:Fragile X Syndrome / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D006115:Greece; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D018911:Trinucleotide Repeats