In the last leg of this article, we discussed the various types, rather physical manifestations of congenital disorders. There are more ways that these affect a child. In this article, we discuss those and more importantly, begin into the how of congenital issues.
Developmental Issues
Developmental issues are not always congenital anomalies but can be a result of them. A few examples of the congenital anomalies that cause developmental issues are:
Down syndrome: A person with Down syndrome is born with an extra chromosome. This affects brain and body development. Around 1 in every 830 babies born in India has Down syndrome.
Visual impairments: A visual impairment affects sight. The cause is an abnormal eye structure or the fact that the brain and eyes do not work together properly.
Hearing impairments: These occur when the ears do not work properly. Most infants need to have a hearing screening before they are 1 month old. They may have some ability to hear, or have a complete loss of hearing. Hearing impairments can be genetic.
Foetal alcohol spectrum disorders: These can occur if a woman drinks alcohol during pregnancy. They can affect learning, growth, and development.
Cerebral palsy: This is the most common childhood motor disability. It affects balance, movement, and posture. It can occur if there is damage to the brain while it is developing.
Muscular dystrophy: This affects the muscles, which become weaker over time. There are different types of muscular dystrophy, depending on the group of muscles they affect.
Genetic disorders: Some genetic disorders can affect development. The most common example is fragile X syndrome. This affects normal brain development and can affect learning and behaviour.
Specific language impairment: This is a communication disorder. It can affect a person’s ability to read, write, and speak.
CAUSES AND RISK FACTORS
An estimated 50 percent of all congenital anomalies have no obvious cause. Some are genetic while others have a link to the woman’s health during pregnancy. It is also possible that environmental factors play a role.
Genetic factors: Genes play an important role in many congenital anomalies. This might be through inherited genes that code for an anomaly or resulting from sudden changes in genes known as mutations.
Chromosome Abnormalities: Chromosomes are structures that carry genetic material inherited from one generation to the next. Twenty-three come from the father; twenty-three come from the mother. The genes carried on the chromosomes determine how the babies will grow, what they will look like, and to a certain extent, how they will function.
When a child is born without 46 chromosomes, or when pieces of the chromosomes are missing or duplicated, he/she may look and behave differently from others of the same age and may develop serious health problems (e.g. Down syndrome).Genetic abnormalities may be of the following types:
Single-Gene Abnormalities
Sometimes the chromosomes are normal in number, but one or more of the genes on them are abnormal.
Autosomal dominant inheritance is a genetic abnormality that can be passed on to the child if one of the parents has the same abnormality.
Autosomal recessive inheritance is a genetic abnormality that can be passed on to the child only if both parents carry the same defective gene (e.g. cystic fibrosis, Tay-Sachs disease, sickle cell anemia). In these cases, both parents are normal, but 1 in 4 of their children would be expected to be affected.
X-linked conditions are genetic abnormalities that mainly occur in males (e.g. hemophilia, colour blindness, forms of muscular dystrophy). Females may carry the abnormal gene that causes X-linked recessive disorders, but they may not show the actual disease.
X-linked dominant conditions occur in both males and females; however, they are more severe in males (e.g. certain neurological conditions affecting the brain, skin disorders and types of skeletal or craniofacial disorders).
Consanguinity (when parents are related by blood) also increases the prevalence of rare genetic congenital anomalies and nearly doubles the risk for neonatal and childhood death, intellectual disability, and other anomalies.
Some ethnic communities (such as Ashkenazi Jews or Finns) have a comparatively high prevalence of rare genetic mutations such as Cystic Fibrosis and Haemophilia C.
Conditions during pregnancy that affect the baby
Substances that may produce physical or functional defects in the human embryo or fetus after the pregnant woman is exposed to the substance are called TERATOGENS. The wordteratogen originates from the Greek word for monster, teratos.These are classified into four categories, physical, chemical, or infectious agents and maternal conditions.
Physical agents include ionizing radiation or other agents that contribute to hyperthermia or elevated body temperature e.g.: X RAYS AND GAMMA RAYS.
Hyperthermia is associated with neural tube defects, spontaneous abortions, and various cardiovascular abnormalities.
Metabolic conditions affecting pregnant females such as malnutrition, diabetes, lupus, and thyroid disorders are a second category of teratogens. Maternal hypertension can affect blood flow to the fetus and impair fetal growth.
Eating raw or uncooked foods during pregnancy can also be dangerous to the health of the mother and fetus and should be avoided.
The third kinds of teratogens are certain illnesses during pregnancy, particularly during the first nine weeks. These can cause serious congenital abnormalities e.g. maternal infections such as STORCH (Syphilis,Toxoplasmosis,Rubella,cytomegalaovirus andHerpesVirus),
Chicken pox. Maternal infections such as syphilis and rubella are a significant cause of congenital anomalies in low- and middle-income countries.
Zika virus infection during pregnancy is a cause of microcephaly and other congenital abnormalities in the developing fetus and newborn. Zika infection in pregnancy also results in pregnancy complications such as fetal loss, stillbirth, and preterm birth.
The fourth kind of teratogen includes drugs and chemicals the pregnant female ingests such as alcohol, cocaine, thalidomide, Agent Orange, and vitamin A and its derivatives, called retinoid.
Alcohol consumption and certain drugs during pregnancy significantly increase the risk that a baby will be born with abnormalities (e.g. foetal alcohol spectrum disorders).
Smoking during pregnancy increases the chance of cleft lip and palate. It can also increase the chance of premature birth and low birth weight.
SOCIOECONOMIC AND DEMOGRAPHIC FACTORS
Low-income may be an indirect determinant of congenital anomalies, with a higher frequency among resource-constrained families and countries. It is estimated that about 94% of severe congenital anomalies occur in low- and middle-income countries.
An indirect determinant, this higher risk relates to a possible lack of access to sufficient, nutritious foods by pregnant women, an increased exposure to agents or factors such as infection and alcohol, or poorer access to healthcare and screening.
Factors often associated with lower-income may induce or increase the incidence of abnormal prenatal development.Maternal age is also a risk factor for abnormal intrauterine foetal development. Advanced maternal age increases the risk of chromosomal abnormalities, including Down syndrome.
Maternal nutritional statusMaternal folate insufficiency increases the risk of having a baby with a neural tube defect while excessive vitamin A intake may affect the normal development of an embryo or fetus.
PREVENTION
Preventive public health measures work to decrease the frequency of certain congenital anomalies through the removal of risk factors or the reinforcement of protective factors. Important interventions and efforts include:ensuring adolescent girls and mothers have a healthy diet including a wide variety of vegetables and fruit, and maintain a healthy weight;ensuring an adequate dietary intake of vitamins and minerals, and particularly folic acid in adolescent girls and mothers;ensuring mothers avoid harmful substances, particularly alcohol and tobacco;avoidance of travel by pregnant women (and sometimes women of child-bearing age) to regions experiencing outbreaks of infections known to be associated with congenital anomalies;reducing or eliminating environmental exposure to hazardous substances (such as heavy metals or pesticides) during pregnancy;controlling diabetes prior to and during pregnancy through counselling, weight management, diet and administration of insulin when required;ensuring that any exposure of pregnant women to medications or medical radiation (such as imaging rays) is justified and based on careful health risk–benefit analysis;vaccination, especially against the rubella virus, for children and women;increasing and strengthening education of health staff and others involved in promoting prevention of congenital anomalies;Screening for infections, especially rubella, varicella, and syphilis, and consideration of treatment.In the next and the final part of this article, we will discuss the diagnosis and management of congenital disorders.
The author is Physiotherapist, In-charge PMRD, Khyber Medical Institute
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author. The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.