Novel polymorphism in the FMR1 gene resulting in a "pseudodeletion" of FMR1 in a commonly used fragile X assay.
The fragile X syndrome is the most commonly inherited cause of mental retardation. Genetic diagnosis of this disease relies on the detection of triplet repeat expansion in the FMR1 gene on the X chromosome. Although the majority of disease in fragile X patients is due to mutations involving triplet repeat expansion, deletion of various portions of FMR1 has also been described in association with the fragile X syndrome. Here we describe a rare polymorphism in the noncoding region of FMR1 that mimics detection of a deletion in a commonly used assay for fragile X syndrome, which can result in misdiagnosis of the disease.
Daly
T M
TM
Department of Pathology, Washington University School of Medicine and St Louis Children's Hospital, Missouri 63110, USA.
Rafii
A
A
Martin
R A
RA
Zehnbauer
B A
BA
D016477:Artifacts; D001483:Base Sequence; D015139:Blotting, Southern; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D003951:Diagnostic Errors; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics*; D005787:Gene Frequency; D006801:Humans; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D016601:RNA-Binding Proteins; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion / Q000235:genetics*
D015246:Deoxyribonuclease EcoRI; D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human