2002-12-01
The X chromosome and fragile X mental retardation
Publication
Publication
Cytogenetic and Genome Research , Volume 99 - Issue 1-4 p. 257- 264
Fragile X syndrome represents the most common inherited cause of mental retardation. It is caused by a stretch of CGG repeats within the fragile X gene, which increases in length as it is transmitted from generation to generation. Once the repeat exceeds a threshold length, no protein is produced, resulting in the fragile X phenotype. Both X chromosome inactivation and inactivation of the FMR1 gene are the result of methylation. X inactivation occurs earlier than inactivation of the FMR1 gene. The instability to a full mutation is dependent on the sex of the transmitting parent and occurs only from mother to child. For most X-chromosomal diseases, female carriers do not express the phenotype. A clear exception is fragile X syndrome. It is clear that more than 50% of the neurons have to express the protein to ensure a normal phenotype in females. This means that a normal phenotype in female carriers of a full mutation is accompanied by a distortion of the normal distribution of X inactivation. Copyright
Additional Metadata | |
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doi.org/10.1159/000071602, hdl.handle.net/1765/58003 | |
Cytogenetic and Genome Research | |
Organisation | Department of Clinical Genetics |
Oostra, B., & Willemsen, R. (2002). The X chromosome and fragile X mental retardation. Cytogenetic and Genome Research (Vol. 99, pp. 257–264). doi:10.1159/000071602 |