Autism, ADHD and the Genetic connection to schizophrenia!

Autism is a condition which is characterised by three distinct modalities, Social interaction, Social integration and Social communication. The disorder is now growing at an alarming rate, and there is no obvious genetic link for this disorder to date. Those without knowledge about psychiatry or biology go on to blame parenting as the cause for developmental dysfunction. Although draconian parenting style does cause damage for development, and is a major cause of trauma, there is now evidence to prove the genetic factors for Autism, ADHD, OCD and Schizophrenia which surprisingly all have a common underlying chromosomal connection!

In the psychiatric community, it has long been known that schizophrenia and autism are directly related, there are several studies that prove this point, although a diagnosis of autism doesn’t necessarily mean you will go on to develop schizophrenia, it simply means you have a disposition to developing it? Underlying genetics play a vital role in the progression from Autism, (if autism has been diagnosed) to full blown schizophrenia. Various explanations for a schizophrenia-autism association are possible. Developmental disorders per se may be risk factors for schizophrenia.

Autism is characterised by lack of empathy, and often presents with behavioural outbursts, these outbursts are due to misunderstanding and processing language. And moreover, they are affected by sensory stimulus, sensory processing disorder and sensory memories!


There are some children who display aggressive outbursts and there are those that don’t? What could be the underlying factor for such a huge difference in the presentation of the two? It can either have a sensory – neurological cause, or a biological cause.

Behavioural and social scientists blame the environment and parental nurturing for the development of the child. Neurological scientists state that sensory stimulus is the underlying factor for behaviour changes and geneticists claim its all biology?

Chromosome 22q11 di-George Syndrome

There are many other different psychiatric labels that overlap with autism, and another one of them is Di-George Syndrome. Geneticists have identified that chromosome 22q11. Also known as VeloCardialFacial Syndrome VCFS (chromosome 22q11) deletion, shows high rates in childhood with autism spectrum disorders and (50%) also present with psychotic symptoms. Children who have VCFS also often have learning difficulties and developmental delays. [1]

VCFS is often characterised with physical abnormalities, such as cleft palette, heart defects; problems fighting infection; low calcium levels; differences in the way the kidneys are formed or work; a characteristic facial appearance; learning problems; and speech and feeding problems, to name a few. [3]

About 65 percent of individuals with the 22q11.2 deletion have been found to have a non-verbal learning disability.

So, this must mean that the other 35% does not have a generalised learning disability and those who are affected, may not even know they have a deletion in chromosome 22q11.2. Because VCFS is often diagnosed on physical deformities as opposed to learning capacity. The paper also notes that Later in life, they are at an increased risk of developing mental illnesses such as schizophrenia, depression, anxiety, and bipolar disorder. [2]

Because the signs and symptoms of 22q11.2 deletion syndrome are so varied, different groupings of features were once described as separate conditions. Doctors named these conditions DiGeorge syndrome, velocardiofacial syndrome (also called Shprintzen syndrome), and conotruncal anomaly face syndrome. [2]

Most people with 22q11.2 deletion syndrome are missing a sequence of about 3 million DNA building blocks (base pairs) on one copy of chromosome 22 in each cell. A small percentage of affected individuals have shorter deletions in the same region.


People with ADHD have an unusually large number of copy number variants (CNVs) — chunks of DNA that are either missing or duplicated, says study researcher Anita Thapar, MD, professor of child and adolescent psychiatry at Cardiff University in Wales. In their study they mention that regardless of intellectual disability, ADHD is a very complex disorder, which will have a number of different genetic factors involved, and also non-genetic, environmental factors. It is this combination that is the likely cause of ADHD [4]

Other research has stated that children with 22q11.2 are more likely than children without 22q11.2 deletion syndrome to have attention deficit hyperactivity disorder (ADHD) and developmental conditions such as autism spectrum disorders that affect communication and social interaction. [2] Therefore, chromosome 22q11.2 is part of the biological cause for ADHD to develop!

Multiple Complex Developmental Disorder (MCDD)

MCDD is observed in children ages 12-18 years and is characterized by impaired sensitivity to social stimuli, as well as thought disorder, bizarre and disorganized thinking, inappropriate affect and mood lability. Although less disturbed than children with autism with respect to social interaction, communication and stereotyped and rigid behaviours, children with MCDD were more disturbed with respect to flagrant thought disorder, anxieties and aggression! [1]

Deletion in the 22q11 region is a highly nonspecific risk factor for several neurodevelopmental disorders (speech and language particularly) as well as other disorders such as Obsessive-Compulsive disorder (OCD).

Nonetheless, the 22q11 deletion is the third largest genetic predictor of schizophrenia! [1]

For instance, the social difficulties present in autism can resemble the social withdrawal seen in schizophrenia, and the underlying chromosome responsible for this connection is 22q11. Which is scientifically referred to as Di George Syndrome. Alternately, under the current diagnostic hierarchy (in which autism and schizophrenia are mutually exclusive) if a person develops autism as a young child, they may be unlikely to receive a diagnosis of schizophrenia later, even if new symptoms emerge.

Therefore, the research is not conclusive in the full development towards schizophrenia, it merely implies the risk associated.

In conclusion, Gene 22q11.2 appears to play a vital role in the diagnosis of ADHD, Autism and is a connective factor to the development of Schizophrenia! Therefore, children with such a diagnosis are born this way as genetics prove their biological cause, which are validated by scientific studies. Disproving the behavioural theories that poor parenting is to blame for these biological conditions.




This post is not intended to alarm those who have one of these conditions. It is meant to inform and educate those who have one of the named conditions to evidence the biological cause and explanation, identifying the genetics behind the condition and the risks of mental health, in later life.

[1]Judith Rapoport, M.D., Alex Chavez, B.S., Deanna Greenstein, Ph.D., Anjene Addington, Ph.D., and Nitin Gogtay, M.D. Autism-Spectrum Disorders and Childhood Onset Schizophrenia: Clinical and Biological Contributions to a Relationship Revisited.

[2] US National Library of Medicine

[3] National Human Genome Research Institute.

[4] WebMD Health News Reviewed by Laura J. Martin, MD on September 29, 2010

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