Cytogenetic versus DNA diagnosis in routine referrals for fragile X syndrome.
The molecular cloning of the gene that causes the fragile X syndrome, and the demonstration that the causative mutation is an expansion of an unstable trinucleotide repeat, suggests that cytogenetic testing could be replaced by a molecular test. We compared the two methods in 525 routine referrals. 12 cases were positive in both tests. 1 case that had a negative DNA test for the fragile site at Xq27.3 (FRAXA), but a positive cytogenetic result, was shown to be caused by a mutation at the FRAXE locus on chromosome Xq28. DNA analysis is a sensitive, reliable, and cost-effective diagnostic alternative.
Wang
Q
Q
Division of Medical and Molecular Genetics, United Medical Schools, Guy's Hospital, London, UK.
Green
E
E
Barnicoat
A
A
Garrett
D
D
Mullarkey
M
M
Bobrow
M
M
Mathew
C G
CG
D000483:Alleles; D002648:Child; D002675:Child, Preschool; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D003582:Cytogenetics; D004247:DNA / Q000032:analysis*; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics; D012017:Referral and Consultation; D014960:X Chromosome
D004247:DNA