The fragile X phenotype in a mosaic male with a deletion showing expression of the FMR1 protein in 28% of the cells.
The instability of the CGG repeat region of FMR1 is not restricted to the CGG repeat but expands to flanking sequences as well. A mosaic fragile X male is reported with a deletion of part of the CGG repeat and 30 bp immediately 3' of the repeat, thus confirming the presence of a hotspot for deletions in the CGG region of FMR1. The deletion, detected in 28% of his lymphocytes, did not impair the transcription and translation of FMR1, suggesting that regulatory elements are not present in the deleted region. The patient has the characteristic fragile X phenotype and assuming that the mosaic pattern detected in the lymphocytes reflects the mosaic pattern in brain, 28% expression of FMRP may not be sufficient for normal cognitive functioning.
de Graaff
E
E
MGC Department of Clinical Genetics, Erasmus University Rotterdam, The Netherlands.
de Vries
B B
BB
Willemsen
R
R
van Hemel
J O
JO
Mohkamsing
S
S
Oostra
B A
BA
van den Ouweland
A M
AM
D000368:Aged; D001483:Base Sequence; D002478:Cells, Cultured; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D009030:Mosaicism; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D016601:RNA-Binding Proteins; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D014158:Transcription, Genetic; D018911:Trinucleotide Repeats
D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human