XLID Genetic Research

GGC has a long and successful history of research on X-linked intellectual disability (XLID). The JC Self Research Institute, a division of GGC, is renowned as an international resource for scientists and clinicians seeking greater understanding of the diagnosis and causes of XLID, as well as prevention and treatment strategies. Many avenues of XLID research are explored at the Institute, from studying the effects of a single gene mutation, to mapping genes along the X chromosome to developing strategies that help families in prevention of recurrences.

An intellectual disability is identified as a condition causing significant limitations in social and behavioral skills and cognitive abilities. It is estimated that up to 3% of the population lives with an intellectual disability (ID). Intellectual disability can be caused by environmental influences, but genetic causes, such as chromosomal anomalies and single-gene disorders account for more than half of moderate to severe cases. 

XLID comprises a group of genetic conditions in which the causative gene mutation is located on the X chromosome. Because males have a single X chromosome, XLID predominantly affects males and is often passed through an unaffected carrier mother. Females with a single X-linked mutation have a 50 percent chance of passing on the mutation to their offspring.

Summary of XLID - Updated May 2019

Newly identified X-linked intellectual disability syndromes and localizations, new gene identifications, the status of nonsyndromal XLID (IDX), and the status of duplications of genes associated with XLID are presented in abbreviated form with appropriate references.  

The linkage limits for XLID syndromes and IDX and the band locations for cloned XLID genes are provided in the accompanying illustrations.  Click to download figures 1A-3 as pdfs.
 
  • Figures 1A and 1B - Location of genes associated with XLID syndromes that have been cloned and mutations demonstrated.
  • Figure 2 - Linkage limits for XLID syndromes which have been mapped (lod score >2), but the genes not yet cloned.
  • Figure 3 – Location of genes associated with IDX and linkage limits for IDX families that have been mapped (lod score >2), but the genes not yet cloned. The locations of the IDX genes that have been cloned are indicated on the left with solid arrows, genes that cause both IDX and XLID syndromes are shown on the right with open arrows.

A table is also available showing the genes associated with X-linked intellectual disability in order of their discovery.  

Meet Reggie Roper

Meet Reggie Roper

Reggie has been part of the GGC family for over 18 years. He has short stature, webbing of his hands, pulmonary stenosis, seizures and hydrocephalus along with developmental delay. He carried an initial diagnosis of cardiofaciocutaneous (CFC) syndrome; however, as genetic testing advanced, GGC made the diagnosis of Noonan-like syndrome with loose anagen hair by identifying a mutation in the SHOC2 gene. He is also an active participant in the Greenwood Community Theatre's Penguin Project. "GGC is...

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