Autism Spectrum Disorder is an epidemic today. It is reported that in US 1 in 50 boys are on the autism spectrum. With such a severity, it is quite surprising that even today we do not know much about Autism. Needless to say there is no test for Prenatal Diagnosis of Autism Spectrum Disorders.
More than 73 years ago a 10-year-old boy, Donald Gray Triplett from Mississippi, US was diagnosed with Autism. At that time in 1943 autism was considered to be extremely rare. In the last 70+ years, the definition of Autism has widened to include Asperger’s syndrome, pervasive developmental disorder and single gene disorders such as Rett syndrome.
Today we know that genetics has a role in the incidence of Autism. Researchers have found that if a family has a child with autism, then the likelihood of the next child having Autism is as high as 25%. However just the genetics does not explain the significant increase in the incidence of Autism, says Professor Simon Baron-Cohen of the Autism Research Centre at the University of Cambridge.
“Everyone recognises that genes are part of the story but autism isn’t 100% genetic. Even if you have identical twins who share all their genes, you can find that one has autism and one doesn’t. That means that there must be some non-genetic factors.”
For a parent of Children with Autism or related disorder, the world goes upside down. Their dreams of great future for their kids gets shattered. These parents obviously want to give the very best to their kid, however, are also worried, what will happen to their child with autism, when they are not there in the world.
Several parents, we came across wants to have another child, however, are bothered by the statistics shared above: if a family has a child with autism, then the likelihood of the next child having Autism is as high as 25%.
Prenatal Screening Tests for Autism Spectrum Disorders
Autism is not very well understood even today. Now Autism is considered to be a complex neurodevelopmental disorder with both brain and body abnormalities / conditions. However, during the last 10-15 years, several patterns have been recognised, which could provide valuable methods to diagnose incidence of autism during prenatal screening in future.
However even today a Prenatal screening test for Autism is not clinically available. However, with the development in the clinical research, several other prenatal screening tests are either available or under development. We will try to capture them here in this article:
Blood Serum Biomarkers
One approach is to compare blood samples from autism patients and healthy individuals to search for what is known as a protein fingerprint – a set of protein levels that is consistently and markedly different in people with autism. So far this has been done relatively successfully in Asperger’s syndrome, forming the basis of a blood test that can diagnose the disorder with 80% accuracy, and there are hopes this feat can soon be replicated for autism disorder. However please note that this method is not available clinically today.
Cell-Free DNA Test
Cell-free fetal DNA test is a prenatal screening test for expecting mothers with a high risk of a birth defect in a fetus. Cell-free DNA are small fragments of DNA circulating freely in the blood and body fluids which are utilised as a valuable biomarker to determine birth defects.
Fetal DNA is first noticed after 22-25 days of fertilisation and its concentrations increase as the time period of pregnancy increases. Diagnostic tests for pregnancy using fetal DNA is possible in the seventh week of pregnancy. Cell-free fetal DNA non-invasive test is used to detect Trisomy 18 and Down syndrome. This test is performed on mothers with high risk:
- They have a child who has a birth defect.
- They had an ultrasound test that showed a possible birth defect.
- Advanced maternal age: 35 years or older
- A fetal ultrasound result that indicates an increased risk of a chromosome abnormality
- A previous pregnancy with a trisomy
- A positive first trimester or second trimester maternal screening test
- A known balanced chromosome translocation (switched chromosome pieces) in the mother or father that is associated with trisomy 13, 18, or 21
- U.S. autism estimates climb to 1 in 50 school-age children, Reuters, Extracted 8/9/2016
- Donald Gray Triplett, Encyclopedia Britannica, extracted 8/9/2016
- Recurrence Risk for Autism Spectrum Disorders: A Baby Siblings Research Consortium Study, Sally Ozonoff, Gregory S. Young, Alice Carter, Daniel Messinger, Nurit Yirmiya, Lonnie Zwaigenbaum, Susan Bryson, Leslie J. Carver, John N. Constantino, Karen Dobkins, Ted Hutman, Jana M. Iverson, Rebecca Landa, Sally J. Rogers, Marian Sigman, Wendy L. Stone; extracted 9/9/2016
- Sex-specific serum biomarker patterns in adults with Asperger’s syndrome. E Schwarz, P C Guest, H Rahmoune, L Wang, Y Levin, E Ingudomnuku, L Ruta, L Kent, M Spain, S Baron-Cohen and S Bahn; extracted 9/9/2016
- Cell-free fetal DNA and RNA in maternal blood: implications for safer antenatal testing. BMJ 2009;339:b2451; extracted 9/9/2016
- A scientist says a blood test that can discern a fetus’s entire genome is coming. MIT Technology Review extracted 9/9/2016