Abstract
We describe a patient with typical clinical features of the fragile X syndrome, but without cytogenetic expression of the fragile X or an amplified CCG trinucleotide repeat fragment. The patient has a previously uncharacterized submicroscopic deletion encompassing the CCG repeat, the entire FMR1 gene and about 2.5 megabases of flanking sequences. This finding confirms that the fragile X phenotype can exist, without amplification of the CCG repeat or cytogenetic expression of the fragile X, and that fragile X syndrome is a genetically homogeneous disorder involving FMR1. We also found random X–inactivation in the mother of the patient who was shown to be a carrier of this deletion.
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Gedeon, A., Baker, E., Robinson, H. et al. Fragile X syndrome without CCG amplification has an FMR1 deletion. Nat Genet 1, 341–344 (1992). https://doi.org/10.1038/ng0892-341
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DOI: https://doi.org/10.1038/ng0892-341
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