Down’s Syndrome and Autism (ASM)

What is Down’s syndrome?

Down’s syndrome is often characterised as having a full or partial extra copy of chromosome 21 and is sometimes referred to as Trisomy 21. It is one of the most common chromosomal conditions at birth.

The presentations of Down’s syndrome can vary drastically. Individuals with Down’s syndrome have mild to moderate intellectual disability, characteristic facial features, and may have treatable medical conditions, such as congenital heart defects, low muscle tone, and low thyroid levels.

Many individuals with Down’s syndrome lead healthy and active lives. As our understanding of Down’s syndrome continues to grow, the clinical and social management of the condition improves – allowing many individuals to have jobs, relationships and even live independently.

Down’s syndrome is the most common chromosomal condition and affects approximately 1 in 1,000 births worldwide. This means that in the UK, around 700 babies are born with Down’s syndrome each year.

(Source: National Center on Birth Defects and Developmental DisabilitiesCenters for Disease Control and Prevention)

What is autism?

Autism is a neurodevelopmental disorder caused by differences in the way that the brain functions. It is present from birth, meaning that you cannot develop autism as you get older, but some of the signs of autism may not be picked up until later in life.

Autism is not a mental or physical illness. You cannot ‘develop’ autism as you get older, nor can it be ‘cured’. Many autistic people lead independent lives, but some people may require additional support to help them with certain things.

Autism is known as a spectrum disorder. This means that there is a large variability in symptoms and presentations, which often manifest very differently in different people.

According to the National Autistic Society, more than 1% of the population are on the autism spectrum. This means that in the UK alone, there are around 700,000 adults and children living with autism.

There is no definitive cause of autism. We know that autism tends to run in families and therefore has a genetic link, but there appear to be many different genetic and environmental contributing factors.

Autism signs and symptoms

Because autism is a spectrum disorder, there is huge variability in the type and severity of symptoms that a person may experience. One individual might not have many obvious signs of autism, whereas another person with autism may have more noticeable verbal and/or physical signs paired with learning difficulties.

Some of the difficulties people with autism face include:

  • Social communication and interaction
  • Repetitive and/or restrictive behaviours
  • Sensory sensitivities
  • Anxiety or mood disorders
  • Meltdowns or shutdowns

Social communication and interaction

People with autism generally have difficulty interpreting both verbal and non-verbal language. Things like the tone of your voice or your body language may not be understood by someone with autism.

Some people with autism might struggle to speak, or may even be non-verbal, whereas others have good language skills but struggle with the interpretation of things like sarcasm. They may also take things very literally, require more time to respond to questions, or echo words or phrases that other people say.

Repetitive and restrictive behaviours

People with autism might adopt repetitive or restrictive behaviours as a soothing technique to help them feel calm and safe.

This can manifest in many different ways. Some might have stringent routines, such as taking the same route to work or school, or eating the same foods at the same time. Some autistic people may use repetitive movements like rocking or hand-flapping. These behaviours might happen when they are anxious or stressed, or simply because they find the repetitive motion enjoyable and soothing.

Sensory sensitivities

Many autistic people experience over- or under-sensitivities to one, some, or all of their senses. They might find bright lights or colours too much, or background noise too loud and distracting and are unable to block it out or ignore it. They may also be over- or under-sensitive to temperatures, smells, tastes, or touch. Some people with autism struggle with certain textures of food or textiles, and might not be able to wear certain clothes due to the discomfort it causes. Some don’t like to be touched and find interactions such as hugging to be uncomfortable.

Being sensitive to stimuli that neurotypical people would not normally react to can cause someone with autism considerable anxiety or even pain.

Anxiety and mood disorders

Anxiety is a common problem for many people with autism, particularly if faced with a challenging situation, like meeting new people or a change of routine.

Whilst autism itself is not a mental illness, autistic people can also experience mental illnesses such as anxiety and depression.  It is therefore important that people with autism are aware of how their surroundings impact their mental wellbeing, as well as finding coping mechanisms to help reduce anxiety.

Meltdowns and shutdowns

Meltdowns and shutdowns are two reactions an autistic person might experience if they become overwhelmed by their environment.

Meltdowns describe a temporary loss of behavioural control. This loss of control can be verbal or physical, such as screaming, shouting, crying, kicking, hitting or biting. A meltdown is not the same as a temper tantrum that you might see in a child. It is a loss of control due to being overwhelmed by the world around them.

Shutdowns are not always obvious to other people. They also occur because the individual is overwhelmed, but rather than having a verbal or physical reaction (like a meltdown), they may become quiet, ‘switched off’ or ‘zoned out’. This can be just as debilitating as having a meltdown, but is less easily recognised.

Autism and Down’s syndrome

People with Down’s syndrome are more likely than the general population to have autism, but the reason why autism is more common in people with Down’s syndrome is not fully understood.

There is also evidence to suggest that other health problems, such as epilepsy, scoliosis and behavioural feeding difficulties are more likely to occur in people with a dual diagnosis of Down’s syndrome and autism (DS-ASD), when compared to those with Down’s syndrome alone.

Some of the symptoms of Down’s syndrome can be similar to those of autism, particularly in terms of behaviour.

If a person has DS-ASD, the characteristics of autism may occur additionally to the ones seen in Down’s syndrome, such as challenges with communication and behaviour.

Similarities between Down’s syndrome and autism

There are some similarities between Down’s syndrome and autism.

People with autism and/or Down’s syndrome can struggle with communication and social skills. Some people with either condition may struggle with eye contact during conversation. Being able to have a reciprocal conversation can be challenging for some people with either autism or Down’s syndrome.

Other similarities can be observed in behaviours, such as:

  • Sticking to a strict routine, e.g. taking the same route to school or work, eating the same food at the same time every day, or wearing the same clothes
  • Playing with toys repetitively
  • Withdrawal or anxiety – in people with Down’s syndrome, this is more common as they become adolescents
  • Meltdowns – these can occur in people with autism or Down’s syndrome and can happen due to sensory sensitivities, feeling unsafe or becoming distressed

Differences between Down’s Syndrome and autism

Despite sharing some similarities, there are many differences between autism and Down’s syndrome in terms of physical appearance, neurological capabilities, communication, behaviour, and other physiological functions.

Physical appearance

People with Down’s syndrome may have some or many distinct characteristics, such as a short neck, large tongue, flat head, a slanted appearance of the eyes, and white spots in the iris.

Autism doesn’t affect physical appearance, and it is usually impossible to tell if someone has autism by their appearance alone.

Neurological symptoms

Many children with Down’s syndrome display developmental delays, meaning that they may reach milestones long after their peers. Each child is different, and the developmental delays in some people with Down’s syndrome may be longer than in others. Most people with Down’s syndrome also have learning disabilities, meaning they might require extra support to help them learn new skills.

Autism differs from Down’s syndrome because it is a spectrum disorder. The range of intellectual capabilities varies from person to person. Some will have high IQs, can learn in similar ways to their peers, and don’t struggle with information retention, whilst others may require extra support in a learning environment.

The difference between a learning disability and a learning difficulty is that a disability affects intelligence and learning ability in all areas of a person’s life, whereas a learning difficulty refers to the challenge of overcoming a particular obstacle or obstacles, regardless of a person’s IQ.

Communication and behaviour

Lots of people with Down’s syndrome are friendly and enjoy socialising with their peers, despite struggling with language, like grammar and sentence structure. Children with Down’s syndrome usually develop language in a similar way to neurotypical children, but this development might be delayed when compared to their peers.

Children with Down’s syndrome are more likely to copy their peers during play and will engage with others. They might also become upset or frustrated with their peers during play, as they don’t always understand how to interact effectively with those around them.

On the other hand, people with autism are more likely to struggle to engage in conversation and can struggle with eye contact. Some autistic people struggle with interpretation and can find it hard to understand people if they are talking abstractly or are being sarcastic, for example.

Autistic people are less likely to engage with peers during play. Sometimes, they may play with similar toys or games next to their peers, but this is often done without interaction or joining in the game.


Down’s syndrome is a complex disability and unfortunately there are many other illnesses or disorders that a person with Down’s syndrome may have. About half of all people with Down’s syndrome have a problem with their heart, such as congenital heart disease. They are also at higher risk of having some blood cancers, as well as endocrine problems, such as hypothyroidism. Up to 20% of people with Down’s syndrome are affected by coeliac disease, compared to just 1% of the general population.

There is less evidence for physiological symptoms in people with autism. Most signs are social- and behaviour-based.

Can a person be autistic and have Down’s syndrome?

A person can have both Down’s syndrome and autism. This is known as a dual diagnosis of Down’s syndrome and autistic spectrum disorder, often abbreviated to DS-ASD.

Roughly 16-18% of people with Down’s syndrome will also have autism. It is hard to determine exactly how prevalent autism is in people with Down’s syndrome because signs of autism can sometimes be mistaken for those of Down’s syndrome during a diagnosis.

Someone with DS-ASD may display characteristics that are not as common in a person with Down’s syndrome alone. These may include problems maintaining eye contact, not engaging or responding to interactions with others, difficulties communicating needs, and a loss of speech or communication.

People with DS-ASD can also engage in more restrictive or repetitive behaviours, like making repetitive sounds or phrases without meaning, or doing repetitive movements that are hard to redirect.

They may become more overwhelmed by their environment, such as by loud or unexpected sounds, bright lights, and textures. They may not want to engage in physical affection such as hugs and can be resistant to grooming tasks such as hair brushing.

Those with DS-ASD can display more meltdowns, can attempt to hurt themselves (e.g. by hitting themselves or banging their head) and can become extremely distressed when faced with small changes to their routine.

People with DS-ASD can find social engagement, communication and regulation of behaviour more challenging than people with a Down’s syndrome-only diagnosis.

Compared with people who have autism alone, those with DS-ASD can show more interest and engagement with their peers socially and display less repetitive behaviours, but may also be slower to process information from the world around them and experience more cognitive challenges.

How does someone get diagnosed with autism?

The first step in obtaining an autism diagnosis is to speak to your GP. If you are a parent of a child who you think may have autism, it might be useful to write down any signs you have noticed to help guide you through the appointment. You might also find it useful to speak to people close to your child, such as friends, family members or teachers, to see if they have noticed any patterns of behaviour that might not always be displayed at home.

If you are looking to find out whether you have autism yourself, speak to friends or family to see if they can describe any behaviours that you might be unaware of. You can write a list of anything that you think could be relevant, to discuss in your appointment.

After speaking to your GP, the next step is to have an autism assessment by a team of specialists. They will ask you questions about any challenges you or your child may face. They might also want to speak to people who you or your child are close to, to help build a bigger picture of how you or your child interacts with the world. The specialists may also ask you or your child to perform certain tasks and watch how you or your child engages with people or objects.

Once the assessment is over, the specialists will write a report that details whether you or your child is autistic.

For more help or information, visit the NHS website.

What is the treatment for Down’s syndrome?

The severity and presentation of Down’s syndrome varies drastically between individuals. Therefore, there is no single standard treatment for Down’s syndrome. Treatments are based on each individual’s medical, developmental and intellectual needs.

What is the treatment for autism?

There is no ‘cure’ for autism, and many autistic people do not see their autism as something that needs to be treated. Whilst autism is a spectrum, with signs ranging from very mild to very severe, autism is not a disability or illness, but just a different way that the brain works.

Similar to Down’s syndrome, autism is a life-long condition. The focus is therefore on how to make life fulfilling and less challenging.

Knowing what triggers sensory sensitivities or overload can help reduce meltdowns or shutdowns. An autistic person should be given space and support when they are feeling overwhelmed with their environment. Finding coping strategies can also help them to soothe themselves, whilst reducing the likelihood of having a meltdown or shutdown.

If you or someone you know has autism, you should speak to a healthcare professional who specialises in autism. They can provide tailored information that can help someone with autism overcome the many challenges they may be faced with.

How can I get Down’s syndrome screening during pregnancy?

A screening test for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome is available at 10-14 weeks of pregnancy.

The screening test that is most widely available is known as a combined test. The combined test comprises of a blood test and an ultrasound scan. The blood test looks at markers found in the blood that can indicate an increased chance of carrying a baby with a chromosomal disorder. The ultrasound scan is used to determine something known as the ‘nuchal translucency’.

The results of both of these tests are used along with the age of the pregnant woman to determine the risk of carrying a foetus with Down’s syndrome, Edwards’ syndrome or Patau’s syndrome.

In the case of a high-risk result from the combined test, the pregnant woman might be offered the chance to receive NIPT, which is another screening test, or diagnostic testing, which may be an amniocentesis or chorionic villus sampling (CVS).

Amniocentesis and CVS will provide a definitive answer as to whether or not the baby has Down’s syndrome, Patau’s syndrome or Edwards’ syndrome, but there is a risk that amniocentesis and CVS can cause a miscarriage. Therefore, many pregnant people are choosing to take a NIPT screening test privately, as it is available to all expectant mothers, irrespective of whether they were classified as high risk by the combined test.

The AlphaBiolabs IONA® NIPT test only requires a blood sample, which can be provided by any expectant mother in the first trimester, from 10+ weeks gestation, and not just those who received a high-risk result from the combined test.

The AlphaBiolabs NIPT test is a laboratory test which detects 97.2%-100% of trisomies in singleton and twin pregnancies. The AlphaBiolabs IONA® NIPT test can also provide foetal sex determination, which is not offered by the NHS. With results available in in 5-7 working days, you can also get results much faster than the traditional testing pathway.

Traditional Screening Tests AlphaBiolabs IONA® NIPT
Multiple procedures over the course of the first and/or second trimester One laboratory test at any time over 10 weeks gestation
Combined screening identifies around 85% of babies with Down’s syndrome and 80% of babies with Edwards’ or Patau’s syndrome The AlphaBiolabs IONA® NIPT test detects >99.9% of babies with Down’s syndrome, Edwards’ syndrome and Patau’s syndrome
Reduced performance of screening in twin pregnancies Equivalent performance of screening in both twin and singleton pregnancies
Results are provided following several tests, which can take some time Results provided within 5-7 working days
Can involve invasive methods that may harm the mother and baby and carry an increased chance of miscarriage Blood test taken from mother’s arm, posing no risk to mother or baby
No gender identification Gender identification available.
Tests for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome only Can look for chromosomal changes in all 46 chromosomes
NIPT, if offered at all, is only offered to pregnancies determined as ‘high risk’ by the combined test Can be taken by any pregnant person, irrespective of the risk status determined by the combined test

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Karolina Baker

Karolina Baker

Health Testing Specialist at AlphaBiolabs

Karolina joined AlphaBiolabs in 2021, and holds the role of Health Testing Specialist.

As well as overseeing a range of health tests, Karolina plays an active role in the research and development of the company’s latest health test offerings.

Before joining AlphaBiolabs, Karolina worked as an Associate Practitioner at Mid-Cheshire Hospitals NHS Foundation Trust, and as a research assistant at the Turner Laboratory, within the Faculty of Biology, Medicine and Health at The University of Manchester.

Karolina’s main scientific interests include clinical genomics and genetic diagnostics. Her qualifications include a BSc in Molecular Biology and an MSc in Genomic Medicine.

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