AsianScientist (Oct. 29, 2012) – Researchers have solved a 40-year mystery for an Australian family beset by a rare intellectual disability that affects only the male family members.
While many intellectual disabilities are caused directly by a genetic mutation in the so-called “protein coding” part of our genes, the researchers found that in their case the answer laid outside the gene and in the regulation of proteins.
Protein regulation involves the switching on or off of a protein by specific genes. As a consequence in this case, either too much or too little of this protein can trigger the disability.
In this month’s issue of the journal American Journal of Human Genetics, Professor Jozef Gecz and his team at the University of Adelaide studied a large (anonymous) Australian family of 100 people, who for generations have not known the source of their genetically inherited condition.
The disability – which results in a lower IQ, behavioral problems such as aggression, and memory loss, and is linked with developmental delays, epilepsy, schizophrenia and other problems – affects only the male family members and can be passed on by the female family members to their children.
Genetic samples taken from the family and laboratory testing involving mice have confirmed that the protein produced by the HCFC1 (host cell factor C1) gene is the cause of this disability.
“The causes of intellectual disability generally are highly variable and the genetic causes in particular are numerous. The vast majority of intellectual disabilities are due to genetic mutations in proteins, so it was rather unexpected that we found this particular disability to be due to a regulatory mutation,” says Gecz.
“We’ve been researching this specific disability for 10 years and it’s taken us the last three years to convince ourselves that the protein regulation is the key,” he says.
The article can be found at: Huang L et al. (2012) A Noncoding, Regulatory Mutation Implicates HCFC1 in Nonsyndromic Intellectual Disability.
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Source: University of Adelaide.
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