Genetic Testing - An Expert Explains (Cont.)

Written by Peppy Health | July 1, 2022

Dr Alan Thornhill continues his in depth explanation of genetic testing in fertility.

What is NIPT?

NIPT is believed to be more accurate than your first pregnancy ultrasound and can help indicate a risk of passing on specific genetic conditions

As you prepare to welcome a child into the world, you may experience anxious feelings surrounding their health. ‘How do I know if my baby’s okay?’ ‘Am I doing anything wrong?’ These may be a few questions that pop into your head. Non-Invasive Prenatal Testing (NIPT) may help settle those moments of uncertainty, as it’s used to check for chromosome abnormalities in a developing foetus by taking a blood sample when you’re pregnant. The test aims to identify a high risk of chromosomal abnormalities without using an invasive procedure – which could bring a small risk of complications in your pregnancy. Most NIPTs screen for a specific set of abnormalities that can lead to your child being affected by a genetic condition such as Down’s syndrome.. Other NIPTs check for abnormalities in all chromosomes and possibly other types of alterations. These blood tests can be performed as early as 10 weeks into your pregnancy and while largely reliable, it’s important to remember that no screening test is 100% accurate. If your NIPT test is positive, you may be advised to confirm the result by having a more invasive test such as amniocentesis – which is when a small sample of amniotic fluid (the fluid that protects your baby during pregnancy) is taken for genetic testing.

Who might be recommended for this type of screening?

Any pregnant woman is eligible for this screening, but you’ll probably be advised to do this test if:

you’ve received a false positive result from an ultrasound,
you’re experiencing a high-risk pregnancy and want to avoid undergoing more invasive prenatal tests.

Are there any risks?

There are no physical risks to you directly, as only a simple blood draw from you is needed for NIPT.

Is it available on the NHS?

NIPT is available to NHS patients, but the eligibility criteria will differ according to the policies in your region. It’s also offered to private patients, costing between £250 and £500. This fee may also include an ultrasound or genetic counselling. The two main tests available privately include:

A screening that checks for chromosomes X, Y, 13, 18 and 21 – the chromosomes most commonly associated with abnormalities that could lead to the birth of an affected child.
A test that looks at all 23 chromosomes as well as microdeletions (chromosomes missing a small but important segment of DNA).

What is POC?

If you’ve gone through the pain of miscarriage, the POC test might help you find some answers

For many people, not knowing why your miscarriage happened is the hardest thing to come to terms with. The majority of miscarriages that take place in the first 12 weeks are due to chromosomal abnormalities, and this is what products of conception (POC) screening tests for. During the screening, foetal tissue from a miscarriage is collected and taken to a lab for examination. You may be asked to collect tissue and keep it safely refrigerated in a sterile saline (salt water) solution until you receive a sample collection kit from a clinic. The test not only identifies the chromosomal make-up of the foetus. It also uses DNA fingerprinting technology to confirm the tissue sample was from the foetus and not from yourself, as the mother. The results from this test may help:

explain why the pregnancy was unsuccessful
provide reassurance that the miscarriage was not caused by something you could control (for example - going to the gym)
guide decisions about future pregnancy

Who might be recommended for this type of screening?

Any woman who experiences a miscarriage spontaneously at home or has medical assistance to remove tissue from a failed or abnormal pregnancy.

Are there any risks?

There are no risks to you directly as a patient as the tissue collected for the test is no longer part of an ongoing pregnancy.

Is it available on the NHS?

Yes, POC is available on the NHS and privately. In most cases, you’ll only be offered an NHS-funded POC test if you’ve had three or more miscarriages. This is referred to as recurrent miscarriage (RM). In private fertility clinics, you can have a POC test after your first miscarriage. A POC test costs between £400 and £500 if you purchase it directly from a laboratory and is more expensive when bought from a clinic. It’s vital that you let your healthcare professional know about your circumstances to make sure that you’re receiving appropriate medical care before, during and after the miscarriage.

What is newborn screening?

Offered to all newborns in the UK, this test is highly recommended to check whether everything is okay with your little one’s health

You’ve just welcomed your baby into the world and want to make sure they’re ready to start their new lives in the best way possible. Newborn screening is one way to test whether things are in working order when it comes to your child’s health. It checks for various health conditions and generally consists of three separate screenings, which include:

a physical examination – usually carried out in the first 72 hours after birth to find conditions related to your baby’s heart, hips, eyes and testicles, if applicable. This is repeated when they are six to eight weeks old.
a hearing screening – typically performed in the hospital after birth or a few weeks afterwards, this screens for permanent hearing loss.

a blood spot/heel prick test – this looks for several disorders and often takes place when your newborn is six days old.

In the UK, newborns are screened for nine inherited disorders, including:

cystic fibrosis – which disturbs your digestion and lungs.

sickle cell anaemia – which affects how oxygen is carried throughout your body.
congenital hypothyroidism – when insufficient amounts of a hormone called thyroxine are produced, this could lead to poor growth and learning disabilities.
six metabolic disorders – phenylketonuria (PKU), medium-chain acyl-CoA dehydrogenase deficiency (MCAD), maple syrup urine disease (MSUD), isovaleric acidaemia (IVA), glutaric aciduria type 1 (GA1) and homocystinuria (pyridoxine unresponsive) are all rare but treatable.

Results...

Results for the physical and hearing examinations are immediate, while it may take up to six weeks to get the results of your baby’s heel prick test. If your child tests positive for one or more of the conditions, they’ll be taken for further screenings before being referred for treatment. The NHS is currently exploring ways to examine for a much larger number of disorders which, while individually rare, could have a profound impact on your baby’s health, quality of life and even lifespan. This is likely to take years to become routine due to its technical and ethical complexity. Private clinics currently offer newborn screening tests that look at hundreds of genes, which in turn, could help find disorders that would need to be treated as soon as possible.

Who might be recommended for this type of screening?

Newborn screening is not compulsory, but it is highly recommended for all babies. For some of the diseases screened, early management may even prevent irreversible symptoms.

Are there any risks?

Your baby may show some signs of discomfort during the screening tests, but it is usually a quick process and won’t harm your baby in any way. As with all tests, there is a small risk of the results being incorrect or not identifying a condition that is present.

Is it available on the NHS?

Yes, newborn screening is provided free of charge on the NHS. If your baby is born in a private hospital, hearing screening and physical examinations may be included in your care package, while genetic testing for health conditions using an expanded newborn screening panel test could cost between £500 and £1,000.

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