Australian scientists have successfully identified 91 genes, 38 of which are new, linked to autism and other intellectual disabilities, the University of Adelaide said on Tuesday.


Prof. Jozef Gecz, head of neurogenetics at the university’s Robinson Research Institute, said the study aimed to better characterize the “genetic architecture” of autism compared to other spectrum disorders, but his team found just eight of the 91 genes were unique to autism.

“There is a growing need to distinguish genes that are more likely to be associated with autism spectrum disorders (ASD) and which ones with intellectual disabilities (ID),” Gecz said in a statement released on Tuesday.

“This research aimed to address some of these difficult questions by looking at a very large, international cohort of 11,730 cases.”

He said while ASDs and IDs are often labelled in one group, known as neurodevelopmental disabilities (NDDs), researchers were keen to identify which of the thousands of genes linked to NDDs were unique to either ASDs or IDs.

While Gecz’s research uncovered and identified 91 genes, including 38 brand new ones, just eight were found to be unique to autism, which would make it marginally easier to identify the disorder.

“For a small group of genes (25) there was a bias for primary diagnosis of ID or ASD, that is, eight genes were primarily affected in patients with ASD and 17 genes primarily in patients with ID. However, the majority of the 91 genes were affected (mutated) in both groups,” he said.

“When patients with mutations in the ASD genes were looked at, these were less likely to have seizures, congenital anomalies or microcephaly. In opposite, they were more like to have macrocephaly, that is, increased brain size, which has previously been associated with some subtypes of autism.”

Gecz added that the “majority” (65 percent) of all genes were inherited, meaning “not all of them are sufficient on their own to cause the disease”.

– Genes –

A gene is a locus (or region) of DNA which is made up of nucleotides and is the molecular unit of heredity. Glossary The transmission of genes to an organism’s offspring is the basis of the inheritance of phenotypic traits. Most biological traits are under the influence of polygenes (many different genes) as well as gene–environment interactions. Some genetic traits are instantly visible, such as eye colour or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that comprise life.

Genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotype traits. Colloquial usage of the term “having a gene” typically refers to having a different allele of the gene. Genes evolve due to natural selection or survival of the fittest of the alleles.

The concept of a gene continues to be refined as new phenomena are discovered. For example, regulatory regions of a gene can be far removed from its coding regions, and coding regions can be split into several exons. Some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs. Therefore, a broad, modern working definition of a gene is any discrete locus of heritable, genomic sequence which affect an organism’s traits by being expressed as a functional product or by regulation of gene expression.

– What Is Autism? –

Autism is a neurodevelopmental disorder characterized by impaired social interaction, verbal and non-verbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child’s life. These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress. The diagnostic criteria require that symptoms become apparent in early childhood, typically before age three.

Autism is due to a combination of genetic and environmental factors. Some cases are strongly associated with certain infections during pregnancy including rubella and use of alcohol or cocaine. Controversies surround other proposed environmental causes; for example, the vaccine hypotheses, which have since been disproven. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood. In the DSM V, autism is included within the autism spectrum (ASDs), as is Asperger syndrome, which lacks delays in cognitive development and language, and pervasive developmental disorder, not otherwise specified (commonly abbreviated as PDD-NOS), which was diagnosed when the full set of criteria for autism or Asperger syndrome were not met.

Early speech or behavioral interventions can help children with autism gain self-care, social, and communication skills. Although there is no known cure, there have been reported cases of children who recovered. Not many children with autism live independently after reaching adulthood, though some become successful. An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.

Globally, autism is estimated to affect 21.7 million people as of 2013. As of 2010, the number of people affected is estimated at about 1–2 per 1,000 worldwide. It occurs four to five times more often in boys than girls. About 1.5% of children in the United States (one in 68) are diagnosed with ASD as of 2014, a 30% increase from one in 88 in 2012. The rate of autism among adults aged 18 years and over in the United Kingdom is 1.1%. The number of people diagnosed has been increasing dramatically since the 1980s, partly due to changes in diagnostic practice and government-subsidized financial incentives for named diagnoses; the question of whether actual rates have increased is unresolved.