| Disease ID | Source | Name | Description |
| 309548 | OMIM | Mental retardation, X-linked, associated with fragile site FRAXE (MRFRAXE) | A form of mild to moderate mental retardation associated with learning difficulties, communication deficits, attention problems, hyperactivity, and autistic behavior. It is associated with a fragile site on chromosome Xq28. Mental retardation is characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. The disease is caused by variants affecting the gene represented in this entry. It is caused either by silencing of the AFF2 gene as a consequence of a CCG expansion located upstream of this gene or by deletion within the gene. Loss of AFF2 expression is correlated with FRAXE CCG(N) expansion. Normal individuals have 6-35 copies of the repeat, whereas cytogenetically positive, developmentally delayed males have more than 200 copies and show methylation of the associated CPG island. |