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10 Genetic Disorders That Can Be Tested For Prenatally (And 5 That Can't)

Having a baby is an exciting — and frightening — time in a mom's life. She can feel the baby growing inside her and sometimes even see the baby kicking and moving around. But even then, she doesn't know how the baby is developing and if he or she is healthy.

Thanks to advances in science, doctors can determine a lot more about what is going on in the mom's womb. They can detect pregnancy complications a lot sooner, but they also have the ability to determine a number of conditions that could impact the baby's health for the rest of his or her life.

There are a lot of women and men who worry about having kids even before they get pregnant because they know of a number of health issues in their family. If they have witnessed a sibling or an aunt or a cousin go through a life changing illness, they may hesitate before bringing a child into the world that might suffer the same fate. They may be reassured that a lot of those illnesses can be picked up during prenatal testing. The results may assuage fears or help the parents make decisions about the pregnancy or plan ahead for the baby's care. Information can be power, but the technology doesn't always have all the answers.

Here are 10 genetic disorders that can be tested for prenatally and five that can't.

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15 Down Syndrome

The No. 1 thing that women know about prenatal screening is that there are tests that could show if the baby has Down Syndrome. While it is not the most devastating diagnosis that can come during the tests, it is the one that has gotten the most attention. The genetic condition happens when a baby develops an extra chromosome in a certain part of the DNA, and it can lead to developmental problems and some birth defects, such as, commonly, a heart condition.

The first sign of Down Syndrome could be detected during a nuchal translucency screening, which includes a blood test and an ultrasound that measures the base of the neck. That could determine if there is a possibility of the condition, but an amniocentesis is the only test that can definitely give the diagnosis before birth, according to Baby Center. Many moms don't go through the testing and are surprised at birth, but on the other side, there is a concern that some people are doing the testing and then choosing to end the pregnancy, which has happened in droves in Iceland. Many babies live happy, healthy lives through Down Syndrome, although there are health challenges that could impact the life of the baby and the parents.

14 Sickle Cell Disease

Sickle Cell Disease is a painful reality for a lot of people, and when parents have a chance of passing it on to their baby, there are a few ways to find out during prenatal screenings. The condition affects the shape of the red blood cells, which can slow or block the flow of blood and oxygen. It can lead to pain in the chest or the bones, swelling in the hands and feet, delayed growth, vision problems and more, so it's important to get treatment as early as possible.

Chorionic Villus Sampling, which involves taking a sample through the vagina during the first trimester, can detect the disease, as can amniocentesis, which is usually performed later. The condition is genetic, but there are millions of people who are carriers of the gene who aren't aware of it, so they aren't aware that their baby could have the issue. Luckily, it can also be detected after the birth if the prenatal testing isn't done. Without treatment, children with sickle cell are at risk of things like stroke, organ damage and even blindness according to the Mayo Clinic, so it is definitely worth the testing if you think you may be a carrier.

13 Cystic Fibrosis

One of the scariest ideas ever is that the baby will struggle to breathe, and for parents who might carry a genetic disposition to cystic fibrosis, it can be truly frightening. Unfortunately, it's not something that will come up in an ultrasound, but it could be found in a blood test.

Cystic fibrosis affects the fluids that are supposed to act as a lubricant in the lungs and other parts of the body. Instead of being thin and slippery, the genetic disease can cause the fluids to be thick and clog up the passageways. If the issue isn't caught early, the baby could suffer from lung damage or intestinal blockages, and with repeated infections, the body would get weaker sooner. Luckily, early screenings and tests have allowed for people to live longer lives with the disease, so if CF runs in your family, it's a great idea to get a blood test to check the baby's health.

12 Spina Bifida

A baby's spinal column is one of the most sensitive parts of the body, and it develops so early that many babies end up with problems long before the mom even knows that she is pregnant. There are neural tube defects that range from being fatal to giving the possibility that the baby could be paralyzed, and the most common is called spina bifida. The amazing thing about spina bifida is that while the baby's spine is very vulnerable to being damaged during the birth, if the doctors have diagnosed the issue, they may be able to perform surgery and possibly cure the baby before the birth.

Spina bifida and other neural tube defects can be tested for during the maternal serum alpha-fetoprotein test. It's a blood test that looks for the protein produced by the baby in the mom's blood, and if it is in high amounts, the doctor knows to move on to other blood tests and sonograms. While doctors can't always save the baby, knowing the diagnosis and having a plan of action can help with the parents and the healthcare providers.

11 Trisomy 18/13

As we discussed before, Down Syndrome happens when the baby has an extra chromosome on a certain strand of DNA, but there are other conditions that can happen when the extra chromosome is at another place. Unfortunately, they can be even more devastating. Trisomy 18 is also known as Edwards syndrome, and unfortunately, many babies do not survive the delivery. Of those who do, less than 10 percent live to their first birthday, although there are some who — with extensive medical care — live into their 20s or 30s.

There is another condition known as Trisomy 13 that is also known as Patau Syndrome. It can also include severe mental and physical problems that may cause the baby to die just a month or so after birth. Both conditions can be detected during first-trimester ultrasounds, and they can be confirmed through chorionic villus sampling or amniocentesis. These are diagnoses that no mother wants to receive, but it may help her prepare to care for or say goodbye to her little one.

10 Mitochondrial Disease

Mitochondria are a part of the cells that have their own blueprint for the body, and if it is off, then a person can suffer from a host of issues from problems with the muscles to hearing issues, kidney problems, vision problems and even problems with the brain. There are a range of diseases that can be effected by the mitochondrial DNA, but for a while, it wasn't tested during prenatal screenings. For families who have a history of mitochondrial disease, that was really scary.

But now, doctors have a few methods of screening when they know there could be a mitochondrial issue in the family history. There is a possibility of finding a diagnosis through chorionic villus sampling, and other previous techniques took a couple of months to determine, according to Science Daily. But a few years ago researchers developed a rapid blood test that can provide answers for parents much more quickly. Since the disease can include severe cases where the baby could die, parents are grateful that doctors have figured out a screening that can help them get a better idea of what is going on with the baby.

9 Tay-Sachs Disease

Asian Newborn baby girl 1 day after the birth, in hospital.

It's rare, but if a child has Tay-Sachs disease, he could get sicker every day he doesn't have treatment. That's why it's so important to get diagnosed and treated right away — even in the womb, if the mother has prenatal screenings that can pick up on the genetic disorder.

With Tay-Sachs, the body doesn't break down fatty substances, so they can build up in the brain and other nerve cells. The baby could have muscle weakness and movement problems. He could have seizures and as the disease progresses, he could end up with vision and hearing loss. There is no cure for Tay-Sachs, but medication and physical therapy, as well as support for his breathing and feeding, could improve his life. Getting a prenatal diagnosis isn't good news, but it could help in figuring out how to care for the baby and give him the best chance possible.

8 Rh Incompatability

This screening is not just about the baby — it's also about the mother. Very early in the pregnancy, the mom's blood will be tested to make sure that her blood and the baby's blood won't be incompatible. The Rhesus factor in blood is what makes a person have O+ versus O- blood, for example (or whatever combination of A, AB or B). Most people have a positive Rh factor, which means that they have a protein on the surface of their blood vessels. But if a new mom doesn't and her baby does, her body will likely try to reject the baby.

Moms who are screened for Rh issues often have to have injections of an immune globulin that can make the pregnancy safer. The screening is really important because of the potential for problems, but luckily modern medicine has allowed doctors the ability to take care of many problems if they arise.

7 Fragile X Syndrome

Defects in the chromosomes can have a big impact on the health of children. Another example is known as Fragile X Syndrome because it is a problem on the X chromosome. Because boys have one X chromosome and girls have two, boys are more likely to have severe problems because of the condition, which can cause developmental delays, intellectual disabilities, social issues, seizures, stuttering and a number of physical abnormalities like a large forehead, an elongated face, protruding ears, loose joints and flat feet.

The genetic issue can show up in screenings, especially if parents are aware that they have the possibility in their family. It can also happen when there isn't any family history, but it can be revealed in chorionic villus sampling or amniocentesis, where DNA is examined. There are various degrees of severity of the disorder, according to the March of Dimes, and if parents learn the diagnosis early, medications and therapies can help children with the condition have happy, healthier lives.

6 Hemophilia

We've talked about a lot of disorders that can impact a variety of organs and have a number of complications. This next one can be managed, but it could be deadly if doctors don't know about the condition before the baby is born. Hemophilia is a disorder that impacts the clotting factor of the blood, so to make sure the baby is healthy, a doctor would have to be very careful in the delivery.

Most women don't show signs of hemophilia, since it is on the X chromosome. They can be carriers, though, and their sons could suffer severe consequences. So moms who might carry the disease should consider having a test where blood is drawn from the umbilical cord to test it before the birth. There could be terrible consequences during the birth, so it's best to know ahead of time.

5 Can't: Heart Defects

Heart defects are the most common birth defect that a baby can have. In fact there are more than 40 different types of congenital heart issues that a baby can have. While some of them show up during prenatal tests, most of the time, parents don't learn of the condition until after their baby is born.

During the 20-week ultrasound, technicians will take a long, hard look at the heart to try to figure out if baby's heart is pumping well. But even then, there are a number of defects that can slip through. At the hospital, doctors will check the baby's pulse oximetry to see if things are working OK, but there are even some heart murmurs that doctors don't pick up on even then. Some people learn that they have a congenital heart defect when they are adults, but that usually means that the heart is working well enough to keep the blood flowing throughout their body. Parents shouldn't be upset if they learn their baby had a heart defect that wasn't picked up during prenatal testing — they should just be grateful that doctors discovered it in time for treatment.

4 Can't: Missing Limbs

That 20-week ultrasound is a big deal because it can pick up on a lot of the issues that could impact the health of the baby and the mother. But the images aren't just a little grainy to the moms and dads who try their best to figure out what their little one looks like. They can also be hard to interpret for the professionals, especially since babies move a lot and there are other factors that could make it hard to get a true picture of all that is going on inside the womb.

In fact, there is a big chance that something can be missed. According to an article about prenatal testing in Slate, research shows that three-quarters of the cases where babies have missing limbs are not discovered until the baby is born. That is, they almost always come as a surprise to the parent. It's still rare, but it can happen — and that is quite a thing to learn after the baby is born.

3 Can't: Polydactyly

On the flip side, there is also a possibility that the baby could be born with extra appendages. It happens for about 2 percent of babies, and most of the time it means an extra "finger," but it can also be a toe. Most of the time, the extra digit is pretty tiny, though, and it doesn't show up on an ultrasound during the 20-week scan. Parents may be surprised at the birth, but in many cases, there is an easy treatment.

Most cases of polydactyly aren't like the "six-fingered man" from The Princess Bride. Usually, the extra digit looks like a little bump and it may be held on by a thin strip of flesh. Some doctors try tying off the area or surgically removing it when the baby is just a few months old, although there are some cases where the digit is fully functioning and it may just have to be a part of the baby's body for his entire life. It can be a surprise, definitely, but that's just a part of life.

2 Can't: Cleft Lip/Palate

As we've mentioned, it can be pretty hard to use ultrasound to get a clear look at the baby in his mother's womb. As moms who have poured over images of their little ones know, it's even harder to find differences when it comes to the face. While mom is trying to see if the baby has her nose, the ultrasound tech may notice an issue with the development of the skin and flesh above the lip. But most of the time, issues like cleft lips and cleft palates go undetected. That's especially true if the lip is intact but the palate is not, according to the Mayo Clinic.

There are a number of genetic syndromes that may make cleft lip or palate more likely, but sometimes it is just something that happens during the development of the baby. It could make it difficult to breathe or eat before surgery is done to repair it. It could also impact speech and teeth and could require a number of surgeries and therapies over time. The good news is that most children can be just fine after their cleft lip or palate is repaired, but that might not help a mom who gets a shock at the birth.

1 Can't: Autism

One of the biggest fears of many moms-to-be these days is that the baby could have a diagnosis on the autism spectrum. That's because of the reports that there are more diagnoses every year, although a number of therapies exist these days to give children a chance to become more highly functioning and happy than ever before. But the truth is that most parents won't find out if their baby is on the autism spectrum until after their birth.

Researchers are actually working on a possible prenatal screening that could determine the likelihood, but many parents worry about that possibility, especially since there are a good deal of parents who choose not to have a baby with a diagnosis of Down Syndrome. Autism isn't a death sentence, so for now, it's probably a good thing that there isn't a prenatal screening for the diagnosis. It's still important for babies to receive interventions as soon as possible so that they can have more success, it's OK to wait until after the baby is born.

Sources: babycenter.commayoclinic.org, sciencedaily.com, marchofdimes.org, slate.com, livescience.com, whattoexpect.com

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