Entries in genetics (2)

Tuesday
May312016

Girls with Autism Spectrum Disorder

According to the CDC, 4.5 times more boys are diagnosed with Autism Spectrum Disorder (ASD) than girls [1].

It is currently unknown if this is the result of a biological protection for the female sex or a diagnostic bias created by tools developed mostly by studying boys with ASD.

What is known is that girls need to have more severe symptoms in addition to their autistic traits in order to be diagnosed compared to boys with same level of autistic traits. [2] Genetic research has shown that compared to boys they need to have higher genetic burden (more mutations) before being diagnosed [2]. Girls may also be getting other diagnoses, such as attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD) or even anorexia instead of an ASD diagnosis. It has been proposed that the clinical phenotype may be different, with girls for example being better able to camouflage their symptoms. [3] 

Brain activation observed in socio-cognitive tasks may be different in girls and boys with ASD. Indeed, a candidate social cognition biomarker (assessed with fMRI) showed promising results in boys but not in girls. [4] Gender may need to be taken into consideration when searching for individual-level neuroimaging-based ASD biomarkers.

 N.Z.

[1] CDC. “Prevalence of autism spectrum disorders among children aged 8 years: autism and developmental disabilities monitoring network, 11 sites, United States, 2010.” MMWR Surveillance Summaries 63(2): 1–22. (2014)

[2] Dworzynski, Katharina, et al. "How different are girls and boys above and below the diagnostic threshold for autism spectrum disorders?." Journal of the American Academy of Child & Adolescent Psychiatry 51.8: 788-797. (2012)

[2] Jacquemont, Sébastien, et al. "A higher mutational burden in females supports a “female protective model” in neurodevelopmental disorders." The American Journal of Human Genetics 94.3: 415-425. (2014)

[3] Szalavitz Maia. “Autism – It’s different in girls.” Scientific American (2016).

[4] Björnsdotter, Malin, et al. "Evaluation of Quantified Social Perception Circuit Activity as a Neurobiological Marker of Autism Spectrum Disorder." JAMA psychiatry (2016).

 

Wednesday
Nov182015

Huntington’s Disease: do you want to know your future?

If there was a genetic disease running in your family, would you want to know whether you will develop it? The documentary “Do you really want to know?” shows three stories of people that have been tested for Huntington’s Disease.

Huntington’s Disease (HD) is a devastating incurable disorder characterized by progressive degeneration of neurons in certain areas of the brain, and results in uncontrolled movements, emotional disturbances, dementia, and weight loss. 

HD is a genetic, inherited disease and each child of a parent with HD has a 50% chance of inheriting the gene and eventually developing the disease. Although people are born with the defective gene, they do not usually develop symptoms until the 30-40s. Not only there is no cure, but not even a treatment that slows down the progression of the disease.

The gene responsible for the disease was identified in 1993 and, since then, genetic testing is available. Before that, people at risk could only hope for the best and watch for the appearance of symptoms, taking life decisions like getting married and having kids without knowing if they would pass the HD to their offspring.

This uncertainty does not longer need to exist but, however, most individuals at risk choose not to be tested and live their lives not knowing if they carry the HD gene.

These people are confronted with the difficult decision of whether or not to be tested. If they receive a positive test, they are effectively receiving a death sentence with an awful end. Even if they receive a negative test, they often think about other family members that may not be so fortunate and develop a sense of guilt.

Check out the documentary to see how people react to their results, some times in surprising ways.

CLG

---

Huntington’s Disease Documentary (2012): Do You Really Want To Know?