13 Apr 26 Additional Genes Linked to Intellectual Disability Identified

MedicalResearch.com Interview with:
Dr. Muhammad Ayub MBBS, MRCPsych, MSc., MD
Professor of Psychiatry Chair Division of Developmental Disabilities
Department of Psychiatry Queens
University Kingston
Kingston ON Canada

MedicalResearch.com: What is the background for this study? 

Response: Intellectual Disability affects about 1 percent of the population worldwide. Genetics play a major role in its etiology. Better understanding of the genetic causes is a necessary step in development of improved diagnosis and treatment. Recessive inheritance where the affected child inherits a defective copy of a gene from both the parents is an important genetic mechanism for prevalence of the disease in populations where within family marriages are common. These types of marital bonds are common in South Asia and Middle Eastern countries. The families where parents are related are an effective resource to study recessive forms of Intellectual Disability.

MedicalResearch.com: What are the main findings?

Response: We collected nearly 200 such families from Pakistan and Iran for genetic studies. We started to collect these families in 2005 and the laboratory methods have advanced in the meantime. By examining the regions of the genome that were shared between family members affected with Intellectual Disability we found a genetic cause in about half of the families we studied. Some of the genes involved were already known to be associated with Intellectual Disability. We discovered 36 new genes that cause Intellectual Disability. We had reported 10 of those in previous papers and reported 26 in this paper. Many of these genes are involved in etiology of other neurodevelopmental disorders like Autism, Epilepsy and Schizophrenia. These are some of the genes we found to be associated with Intellectual Disability; ABI2, CCDC82, MAPK8, MBOAT7, MPDZ, PIDD1, SLAIN1, TBC1D23, TRAPPC6B, UBA7, and USP44. These genes play an important role in development and functioning of brain.

MedicalResearch.com: What should readers take away from your report?

Response: Studying families with Intellectual Disabilities where multiple people are affected is an efficient method to unravel the genetic causes of the disease. Understanding the genetics has major implications for diagnosis. If we find a genetic mutation in a family we can immediately help the family by testing relatives and providing genetic counseling to prevent further cases of Intellectual Disability. The burden of providing care to people with Intellectual Disability mostly falls on the families in low and middle income countries where most of the within family marriages take place. Potential of prevention of further cases is a huge benefit.

The benefits of this research is not limited to only those populations. In our experience the genes discovered in families where within family marriages play a role are found at the root of many cases of Intellectual Disability in populations without within family marriages. Some of the genes we discovered few years ago using this technique were later on found in cases of Intellectual Disability in Europe and North America. These findings will help in developing genetic testing panels all over the world.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: There are two major recommendations for future work;

1) This work needs to expand and many more families need to be studies to discover more genes. There are thousands of different genes involved in Intellectual Disability and only a fraction of those has been identified.

2) Further work to understand the functioning of these genes, how they affect the brain development and functioning will eventually lead to a better understanding of the disease and development of novel treatment.

MedicalResearch.com: Is there anything else you would like to add?

Response: Intellectual Disability is somewhat neglected area of research. Better funding in this area will enhance our understanding of the disease and will lead to cure for a proportion of population.

Citation:

Molecular Psychiatry advance online publication 11 April 2017; doi: 10.1038/mp.2017.60

Mapping autosomal recessive intellectual disability: combined microarray and exome sequencing identifies 26 novel candidate genes in 192 consanguineous families

R Harripaul^1,2, N Vasli¹, A Mikhailov¹, M A Rafiq^1,3, K Mittal¹, C Windpassinger⁴, T I Sheikh^1,2, A Noor^5,6, H Mahmood¹, S Downey^1,7, M Johnson^1,7, K Vleuten^1,7, L Bell^1,7, M Ilyas⁸, F S Khan⁹, V Khan⁹, M Moradi¹⁰, M Ayaz¹¹, F Naeem^11,12, A Heidari^1,13, I Ahmed¹⁴, S Ghadami¹⁵, Z Agha³, S Zeinali¹⁵, R Qamar^3,16, H Mozhdehipanah¹⁷, P John¹⁴, A Mir⁸, M Ansar⁹, L French¹⁸, M Ayub^11,12 and J B Vincent^1,2,19

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Last Updated on April 13, 2017 by Marie Benz MD FAAD