The structural and functional deviations occurring at the time of birth, ultimately causing IDD (intellectual & developmental disability), physical disability along with other health problems, are known as birth defects. Some of the problems, if not taken care of or not detected or treated for any given reason at the early stage may be fatal.
How many types of birth defects are there?
Different researches have found out various types of birth defects. As per the findings of CDC, leading causes of infant deaths (within 1st year) in the USA are birth defects. However, only 2 types of birth defects have been categorized in a broader sense.
The 2 types of birth defects are 1) structural birth defect and 2) Developmental or functional birth defects:
1) structural birth defect
If a baby is born with abnormal body parts or abnormal structure, the case is considered as structural birth defects. This type of birth defects can include:
· Abnormal limbs of many types, just like a clubfoot
· Cleft palate or cleft lip
· Heart defects like misshaped or missing valves
· Neural tube defects, the example can be spina bifida and many such defects which can deter the growth & development off the baby’s spinal cord and brain.
2) Developmental or functional birth defects
Developmental and functional birth defects are linked with the functions of the body systems or the body parts of the baby. Due to these problems, the baby will have developmental and intellectual disability. The IDD or intellectual & developmental disability include:
Ø Brain or nervous system problem: The baby’s problems may include IDDs, speech or language difficulties, behavioural disorders, movement trouble and seizures. If the nervous systems of the baby is affected, problems like Down syndrome, Fragile X syndrome and Prader-Willi syndrome etc. will be the cases
Ø Metabolic disorder: Due to this birth problem, the baby will have some types of chemical reactions. The examples are: the baby may not have automatic system of flushing out harmful chemicals or waste materials. The commonly known 2 types of metabolic disorders are 1) phenylketonuria and 2) hypothyroidism.
Ø Sensory problems: Due to this problem the baby may have visual or hearing problem, resulting to blindness or deafness.
Ø Degenerative disorder: This problem may not be apparent at the time of birth, but with the progression of age, different aspects of body functions may go to worsening positions. The examples of degenerative disorders are X-linked adrenoleuko dystrophy and muscular dystrophy. These problems are linked with adrenal glands and nervous systems. Some of the cases of birth defects are caused by many factors; some of them are combined factors. Many of the recognised birth defects do permanent harms to processes or the parts of the body, which ultimately impair the structural and so functional problems.
Recent researches on nature and causes of birth defects
Recent research conducted by NICHD in the year 2016-14 has found out different causes of birth defects. They are:
Ø Osteogenesis Imperfecta is abbreviated as OI. The problem is a genetic disorder. The characteristic of the problem is the fragile bone that gets easily broken. Till recent times, the scientists were not fully aware of the mechanisms that are responsible OI to make the bones fragile.
NICHD research findings reveal that TGFβ (transforming growth factor beta) is a high level of protein in mice, which have the similar bone problems which are detected in OI. As per the researchers, the signalling of TGFβ can lead to future treatment for OI.
Ø Gordon Syndrome
GS or Gordon Syndrome which is also known as (DA) type 3 or distal arthrogryposis is a rare genetic disorder. The characteristics of this disorder are shortened upper and lower limbs (hands and feet) and cleft palate. All these types of DAs involve some types of joint contractures. In this condition, one or many joints are permanently fixed, either in a straight position or in a bent position.
NICHD, in this year, has come up with the new findings that several families have mutations in the PIEZO2 genes which are from the GS families.
In many occasions, the persons with GS are seen with the same symptoms of those people who are suffering from other type of DA or DA5 (DA type 5) or another disorder called MWS (Marden-Walker syndrome). All these 3 disorders were previously known to be different disorders. But after screening by the researchers, it was established that those with the genes DA5 and those with the genes of MWS have the same genetic mutations which are found among the people with GS. This clears the fact that all these 3 disorders are not only related with each other but also found to be different forms of same problem.
Ø Cornelia de Lange Syndrome
Another genetic disorder is known as Cornelia de Lange Syndrome which is responsible for causing different types of range of cognitive and physical issues, which have connections with the missing or malfunctioned limbs. The problem of the cause is the deficiency of the Nipbl protein, but the exact cause is still not known to the researchers.
NICHD researchers used both mouse models and zebra fish for learning about the ways of lowering the labels of Nipbl protein which causes limb defects. The researchers came out with the findings that if Nipbl proteins are suppressed, both the mice and the Zebra fish produce babies with shorter and malformed forelimbs. Other than these discoveries, the scientists have come up with new discoveries of genetic changes, in addition to those findings that are related with the limb development. If the levels of Nipbl are decreased, it definitely affects those genes which are responsible for regulating limb development. These genes are shha, hand2, and hox family.
Ø Freeman-Sheldon Syndrome
The Syndrome, Freeman-Sheldon is also known as DA2A (DA type 2A), which is the severest of the DA type 2A syndrome. Contractures in the facial muscles and in hands in addition to malformed feet are the examples of DA2A syndrome. Different people get affected in different ways from this same problem, but according to the scientists all the cases are mutational causes of MYH3 gene.
46 families were genetically tested by NICHD for investigating on Freeman-Sheldon syndrome. 93 % of these families had MYH3 mutations. The specific mutations, responsible for 91 % of the cases are p.T1781, p.R672H and p.R672C. Among these three mutations, the first one i.e. (p.T1781) was found to be the most severe one.
Influence of gene mutations
With a view to better understanding the way gene mutation can influence the Freeman-Sheldon Syndrome. Medical experts have classified DA2A into 2 groups, depending on their severity. The classifications are done for better understanding of the problem & its management.
Researchers of NICHD have come up with some important findings on polydactyl, which is a birth defect that makes a person with extra toes or extra fingers. One of the genes was found to have problem, which is responsible for making the complexity of the protein. The name of the problem is “as Endosomal Sorting Complex” that needs ESCRT-II i.e. Transport II. This is responsible for causing polydactyl version in mice. In case ESCRT-II is not properly functional it can build up protein on the cell’s surface.
It was also found by the researchers that there is some involvement of unexpected cellular pathway for generating extra digits. Further expansions of the findings on genetic pathways are still on to solve the problem attached with the limb development. The researchers are also expected to come up with new direction towards the human mutations that cause extra toe or limb.
Statistics of persons with birth defects
As per the findings of CDC, out of 33 infants in USA, 1 is the victim of birth defect.
Birth defects during pregnancy
Birth defects during pregnancy are not uncommon phenomena. A few of these pregnancies are more risky than others. The following reasons are highly responsible for birth defects:
Ø Alcohol consumptions: Alcohol consumptions during pregnancy are one of the main reasons for the birth defects. The example: Alcohol consumptions during pregnancy results to foetal alcohol syndrome. The syndrome has the characteristics of IDD, behavioural problems, physical challenges. No medical theory supports or prescribes for any type of safe level of alcohol consumptions during pregnancy. According to the findings of CDC, out of 10 pregnant women, at least 1 and some times more than one women of such stage of their life are found to be alcoholic during the month they have just passed by.
Ø Folic acid deficiency: According to medical science, women who are either pregnant or most likely to be pregnant must take at least 400 micrograms of folic acid in every day, as the preventive measure of NTDs (neural tube defects). CDC suggests that out of every 5 women, 2 in their child-bearing age should take folic acid in every day.
Ø Cigarettes smoking: Cigarettes smoking is very much health hazardous for the pregnant women. Many problems are hell-bent with this addiction. Asthma and such other lung conditions can be the ill-effect of this addiction. It is evidentially proved that many of the babies from Cigarette addicted mothers give birth to the babies with the intestine and heart problems. Many other babies from such mothers have higher risk of SIDS (sudden infant death syndrome).
Ø Infections: The pregnant mothers, if infected due to some reason, are highly risky of giving birth to a baby with birth defects. The example: some of the infections that cause birth defects are cytomegalovirus. Cytomegalovirus is such a virus that travels through body fluids, without causing any symptom to any healthy person. The other infection, toxoplasmosis is parasitic in nature and gets spread through raw meat, cat faeces and contaminated water and food.
Ø Medication use: Many medications taken during pregnancy cause birth defects to the new born. Thalidomide is such a medicine which is taken for different serious conditions. Besides this, cancers were earlier used to treat morning sickness. Now it is discovered that these medicines cause birth defects. The pregnant women, who use to take Thalidomide, give birth to the babies with both structural and functional problems. The problems also include shortened limbs and misshapen ears. However, use of Thalidomide has become very stricter, but a few other medicines in these days are causing similar types of birth defects for the new born. These medicines are not tested for efficacy or safety for the pregnant woman. Hence it is advised that pregnant women and those who are likely to be pregnant should consult doctors before taking such medicines.
Ø Using drugs: Different types of drugs are the causes of various types of birth defects that include behavioural problems and IDDs. The birth defects can also affect heart, urinary system, defects in the arms and legs.
Ø Uncontrolled diabetes or obesity: As per some NICHD sponsored researches, those pregnant women who are obese, are most likely to give birth to babies with heart defects. Many other health problems, including long-term health problems are associated with obesity. In case obesity is not controlled for the pregnant women, the new born are most likely to be too large and also have the poor health outcomes and breathing problems. Of course, these outcomes can also happen to those pregnant women who may or may not be type 1 or type 2 diabetic before getting pregnant.
Birth defects causes
Different causes are there for different types of birth defects. A specific condition is responsible for any of the following types of problems:
è Chromosomal problems: Some of the birth defects are due to some chromosomal or part of chromosomal problems, such as McCune Albright syndrome. In the same manner the problem may be due to the missing of either some gene or part of the gene. The examples may be tumour syndrome. The cases happen when a woman misses X chromosome. Some of the birth defects can also happen if a female has extra chromosome. The examples of the problem are Down syndrome and Klinefelter syndrome.
è Pregnant women exposed to chemicals and medications or some other agents: Infants of the pregnant mothers who used to take thalidomide are most likely to be born with birth defects. In the same way rubella, which is also known as German measles, is also found to be the other type of problem to cause birth defects and some other toxic chemicals, example is hydrocarbons.
è Genetic problems: 1 or more than 1 types of genes might have either change or have mutations that do not work properly. The example may be McCune Albright syndrome. In this case, a gene or some part of the gene may be missing.
Diagnosis of the birth defects
Diagnosing birth defects are completely parts of the affected body and individual problem dependant. It is true that the causes of the defects are not very simple to be detected, but a few defects are easily detectable, example is cleft lip, extra limb or extra organ etc.
Other than these, many birth defects cannot be detected very easily by simply looking at the new born. A process called ‘new born screening’ that involves screening of new-born’s blood for different types of health conditions, including birth defect can find out the problems, which can have lifelong effects.
A few of the birth defect infants, who inherit their defects, need additional testing at birth for detecting the abnormalities they are born with and the possible remedies, if at all available for them. Monkeys disease is one of such kind of disease, for-which treatment can be started before the problem can occur.
Some pregnant women with history of certain conditions and those pregnant women who are more than 35 years of age, need their foetus prenatally checked for any type of birth defects. Two types of prenatal birth defects are there. They are:
1) Amniocentesis: Amniocentesis tests are done for specially diagnosing about the presence of genetic disorder the fetus may have.
Tests: - A small amount of fluid is taken out from the womb by using a needle. The fluid is known as amniotic fluid. This fluid contains the cells with genetic material. These genetic materials are the same genetic materials which the feutus is carrying. The collected cells are grown in a laboratory for examining their genetic material for finding the problem there-in. In case the amniocentesis elements are detected in the fluid that contains womb-cells, the problems are diagnosed as some types of muscular dystrophy and Down syndrome.
Associated problem from amniocentesis: Feutus with this problem become the victims of miscarriage for at least .5 per cent of the cases. These types of tests are done only for those cases with-which genetic disorders or such types of other problems are found to be high.
2) CVS (Chorionic Villus Sampling): Same process of fluid extraction like Amniocentesis is followed from the womb, but exclusively from the cells of chorionic villi. These are the tissues in the placenta, which is the nourishing organ of the fetus. The genetic materials found from the cells of chorionic villi are just similar to the fetus cells.
CVS is also tested for knowing about the chromosomal disorders, which can lead to different genetic problems that includes Down Syndromes.
Differences between these two tests:
Amniocentesis tests are done later than CVS tests. That means CVS tests are done in earlier stage. But CVS tests are more prone to miscarriages, if compared with Amniocentesis tests. In Amniocentesis tests only .5 per cent cases of miscarriages are reported while CVS tests related miscarriages are reported to have 1 per cent of miscarriages. If the doctors detect high risks of birth defects then only they go for CVS tests.
Birth defect related Treatments
Due to the various types of birth defects, the treatments there-in are also different. Treatments may be anything among therapies, medications, surgeries and assistive devices.
Example: MOMS (Myelomeningocele Study) cases’ management required surgical procedure on the fetus for correcting a serious type of spina bifida when the feutus was very much in the womb. The surgery is fully risky. However the surgeries did bring down the health complications for the infants, who were still in the uterus.