Birth Defects

Here are a few birth defects, some common and some rare, that women may worry about.  All of these are able to be diagnosed before birth by screening and diagnostic tests.

Contents of Page

Genetic/Chromosomal Birth Defects

• Trisomy 21- Down’s Syndrome
• Trisomy 18- Edward’s Syndrome
• Trisomy 13- Patau Syndrome
• Cystic Fibrosis

Neural Birth Defects

• Myelomeningocele
• Anencephaly
• Iniencephaly

Congenital Birth Defects

• Tetraology of Fallot

Structural Birth Defects

• Cleft Lip and Cleft Palate
• Upper Limb and Lower Limb Reduction Defects

GENETIC/ CHROMOSOMAL BIRTH DEFECTS

Trisomy 21- Down’s Syndrome  

Individuals with Down’s Syndrome have a third copy of chromosome 21.  This extra chromosome is acquired through nondisjunction of chromosome 21 in either the egg or the sperm before fertilization.  When fertilization occurs the nondisjunctioned chromosome acquires another copy of the chromosome bringing the total to 3 copies of chromosome 21 and 47 chromosomes total.  The cells start to rapidly divide with each new cell containing the extra chromosome 21.  Another form of Down’s Syndrome is caused by translocation of all or part of chromosome 21.  This means that all or part of chromosome 21 is attached to another chromosome, such as chromosome 14.  These individuals still show the characteristics of Down’s Syndrome.  The last form of Down’s Syndrome is a mosaic form.  In this form, the nondisjunction happens after fertilization during the first few cell divisions.  Once the nondisjunction happens, every progeny cell of that cell will have three copies of chromosome 21.  The end result is about half of the fetus’s cells have two copies of chromosome 21 and half have three copies of chromosome 21.

Down’s Syndrome causes mental retardation, slow physical development and other wide ranging symptoms.  They can have heart disease, vision and hearing problems, they are prone to hip problems, dementia and more.  Babies typically feature upward slanted eyes, a single deep crease in the palm, a low nose bridge and more.  Babies born with Down’s Syndrome are able to lead long and productive lives so long as health issues are addressed.

(Photo credit: http://www.methodsofhealing.com/the-down-syndrome-in-children/)

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Trisomy 18- Edward’s Syndrome

Babies diagnosed with Trisomy 18 have three copies of chromosome 18.  The cause of this is the same as Trisomy 21, the sperm or egg contribute a nondisjunctioned chromosome 18 and the other gamete contributes it’s chromosome 18, bringing the total to three.  The cells then divide copying the three 18 chromosomes into every cell.  Trisomy 18 also has a translocated form where the chromosome 18 is translocated onto another chromosome and a mosaic form.

Many babies never make it to term and 50% that do are stillborn, with male babies being less likely to live.  Although less than 10% make it to their first birthday, some babies, mostly girls, are able to live to their teens and even twenties.  Babies with Edward’s Syndrome exhibit mental retardation delayed physical growth, as well as many other symptoms.  These include, heart defects, kidney problems, clenched hands, rocker-bottom feet, digestive problems and more.

(Photo credits:http://www.bustedcranium.com/?p=801…..http://www.judewolpert.com/keyword/saskiap/1/771922831_whZGU/Medium…..http://shanebrayfamily.blogspot.com/2010/03/trisomy-18-awareness-day-march-18-2010.html)

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Trisomy 13- Patau Syndrome

Babies that are diagnosed with Trisomy 13 have three copies of chromosome 13.  This is typically caused by nondisjunction of the sperm or egg’s chromosome 13.  Patau Syndrome also exhibits the forms caused by translocation and mosaicism.

Around 80% of babies born with Patau Syndrome do not make it past their first month of life.  If they do survive the neonatal period they  have mental retardation, delayed physical development, close set eyes (even cyclopia) and 60% of babies have a cleft lip and/or a cleft palate.  They may also have heart disease, polydactyly, syndactyly, eye problems, hernias, etc.

• This baby was born with Trisomy 13 and exhibits cyclopia.

(Photo credit:http://www.diagnosticpathology.org/content/2/1/48/figure/F1?highres=y)

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Cystic Fibrosis

Cystic fibrosis is caused by a mutation in a recessive gene.  A child must receive two copies of the mutated gene to inherit the disorder.  The mutated gene is unable to make the protein cystic fibrosis transmembrane conductance regulator.  This protein directs the making of chloride channels in the mucosa which allow for the passage of chloride and water molecules.  Because the channels are not functioning properly, water and chloride molecules can’t pass to make the mucus thinner. Cystic fibrosis presents in the digestive tract before birth.  It is not until after birth that the disease affects the lungs.  There are many different kinds of mutations which cause different severities of the disease and it’s symptoms.  The defective gene causes the mucus in the respiratory and digestive system to be abnormally thick.  It sometimes affects the reproductive tract and sweat glands as well.

Symptoms of cystic fibrosis are caused by the thick mucus.

• Mucus obstructs the airways causing repeated lung infections that cause the lungs to scar overtime.
• Mucus clogs the pancreatic duct which prevent digestive enzymes from aiding in digestion.  This can cause malnutrition, intestinal blockage, constipation, weight loss and more.
• In the male reproductive tract it clogs the vas deferens causing improper development and infertility in men.  Infertility in women is less common.

The average lifespan for someone with cystic fibrosis is 35 years.  Most often death results from respiratory complications, such as pneumonia.

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NEURAL BIRTH DEFECTS

Myelomeningocele

Myelomeningocele is a common type of spina bifida. Normally, during the first month of pregnancy the two sides of the spine converge and cover the spinal cord, spinal nerves, and meninges. Myelomeningocele is the result of when the spinal meninges fails to completely cover the spinal cord.

If left untreated, most babies die within their first year of life. Babies that are untreated are lucky to live pass one year and usually experience complications during their second year of life. These infants are susceptible to hydrocephalus and intracranial infections.

(Photo credit: http://edua2800.pbworks.com/w/page/11995894/Spina%C2%A0Bifida%C2%A0-%C2%A0A28)

The symptoms of myelomeningocele are:

• loss of bladder and bowel control
• meningitis
• paralysis of the lower limbs

If a myelomeningocele is detected early in pregnancy, treatment options are genetic counseling or a therapeutic abortion. After birth, the treatment is usually an intensive surgery. If the infant has hydrocephalus, a ventricular peritoneal shunt is placed in the infant to assist in the drainage of CSF.
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Anencephaly

The absence of the large part of the brain, the cerebrum, in a developing fetus is known as anencephaly. This is a result of when the neural tubes fail to close. It is uncertain of why this happens but research suggests that it may be due to environmental factors, such as the level of toxins ingested by the mother.  Another possible factor is the expecting mother’s diet. Having a low level intake of folic acid has a correlation of anencephaly in developing fetuses.

(Photo credit: http://media.photobucket.com/image/anencephaly/sunajXaon/anencephaly.jpg?o=11)

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Iniencephaly

(Photo credit: http://library.med.utah.edu/WebPath/TUTORIAL/PRENATAL/PREN019.html)

A rare, but possible, neural birth defect is known as iniencephaly. It is similar to spina bifida but a little more severe. Iniencephaly is the backward bending of the head of the fetus. When the baby is born the neck is absent and the skin of the face is directly attached to the skin of the chest. The scalp is connected to the skin of the back.  There are some factors that may cause iniencephaly. Women who take antiepileptic, diuretics, antihistamines, and sulfa drugs increase their risk of iniencephaly so pregnant women should avoid taking these drugs. Another factor is diabetes and obesity.

What happens when this occurs? Is there a possible treatment for the infant? Unfortunately, there is not a treatment for iniencephaly. Infants who are born with this defect only live a few hours. The best way to avoid iniencephaly is prevention. Pregnant women should monitor their intake of vitamins and minerals. Studies have shown taking at least 4 mg of folic acid increases prevention of neural tube defects up to 70 percent. Since this is a rare defect, there is still ongoing research of other ways to prevent iniencephaly.
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CONGENITAL HEART DEFECTS

– A defect results when the heart or blood vessels near the heart don’t develop normally before birth.

Tetraology of Fallot is rare but, it is the most common form of cyanotic congenital heart disease. This condition causes low oxygen levels in the blood. Patients with Tetraology of Fallot have a higher incidence of major non-heart congenital defects. Classic forms of Tetralogy include four related defects of the heart and its major blood vessels:

• Ventricular Septal Defect (VSD) – a hole, or holes, between the right and left ventricles  of the heart. It  is one of the most common congenital heart defect and is a common occurence because, as the fetus develops, a wall forms to separate these two ventricles. If the wall does not develop all the way then the hole is present . It may occur by itself or with other congenital diseases.
• Pulmonary Stenosis-Occurs when the pulmonary valve does not fully open and thus prevents normal blood flow into the lungs. The pulmonary valve is the valve that separates the pulmonary artery from the right ventricle.
• Overriding Aorta- a defect in the aorta that allows oxygen-poor blood from the right ventricle to travel directly to the aorta and thus bypassing the pulmonary artery altogether.
• Right Ventricular Hypertrophy- a thickened muscular wall of the right ventricle that causes a decrease in blood flow to the pulmonary artery. Thus, increased work on the papillary wall causes a thickening and inefficiency in pumping blood to the pulmonary artery.

Symptoms

Tet spells
Spells are caused by a rapid drop in the amount of oxygen in the blood. Babies develop deep blue skin, nails and lips after crying, feeding, having a bowel movement, or kicking his or her legs upon awakening. Toddlers or older children may squat when they are short of breath. Squatting increases blood flow to the lungs. Tet spells are more common in young infants, around 2 to 4 months.

Treatment

Surgery to repair Tetralogy of Fallot is done when the infant is very young. Sometimes more than one surgery is needed. When more than one surgery is used, the first surgery is done to help increase blood flow to the lungs.

(Photo credit: http://emedicine.medscape.com/article/120083-overview”)

Surgery to correct the problem may be done at a later time. Often only one corrective surgery is performed in the first few months of life. Corrective surgery is done to widen part of the narrowed pulmonary tract and close the ventricular septal defect

Tetralogy of Fallot is often diagnosed during infancy or soon after. However, Tetralogy of Fallot may not be detected until later in life, depending on the severity of the defects and symptoms. With early diagnosis, followed by appropriate treatment, most children with Tetralogy of Fallot live relatively normal lives, though they’ll need regular medical care and may have restrictions on exercise
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STRUCTURAL BIRTH DEFECTS

Cleft Lip and Cleft Palate

(Photo Credits: http://homepage.powerup.com.au/~cleftpal/photogallery_uni_pal.htm ….  http://healthfiles.net/disease/cleft-lip/)

Cleft lip and palate are malformations of the upper lip and roof of the mouth that may occur early in pregnancy. In general, these defects develop when there is not enough localized tissue in those areas, which leads to the available tissue not converging correctly. They are one of the most common birth defects diagnosed in the United States.

• Cleft lip is a split between two sides of the upper lip that can appear as a small notch, or a large splitting from the lip to the base of the nose and includes the bones of the upper jaw.
• Cleft palate is the splitting or an opening of the roof of the mouth and can stretch the entire area: from the hard palate to the soft palate.

Since the lip and the roof of the mouth develop separately, you are able to get either cleft palate without a cleft lip, cleft lip without a cleft palate, or both at the same time. The cause of these birth defects is unknown but many believe that it is a combination of genetic and environmental factors such as viruses, drugs, and other toxins. Some medications considered possible causes for cleft palate and lip are anti-seizure drugs and Accutane and methotrexate including acne medications. Early diagnosis can be seen through ultrasound and will be apparent with physical examination after birth. Complications for babies include, eating problems (cleft palate), ear infections due to build up of fluid in the middle ear, speech problems, poor growth, dental problems shown through malformed or displaced teeth and an increased number of cavities.

Although treatment of cleft palate and cleft lip is a very long and exhaustive process through a large team of specialized dentists, plastic surgeons, and therapists used to treat all the complications, most children are able to live a relatively normal and healthy life.

Below is an example of the repair of unilateral cleft lip. *WARNING: Video may be extremely graphic to some individuals*

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Upper Limb and Lower Limb Reduction Defects

This is another very common birth defect in the United States and is defined as either an upper or a lower limb failing to form during pregnancy. Diagnosis includes the absence of the complete limb, failed separation of fingers and toes, duplication, overgrowth, undergrowth, or congenital constriction band syndrome (ruptured amnion membrane being entangled in the extremities of the fetus).

(Photo Credit: http://embryology.med.unsw.edu.au/Notes/images/skmus/clr.jpg)

The direct causes of limb reduction defects are unknown although it is hypothesized that chemicals, certain medications, and exposure to tobacco smoke may increase the risk of having a child with this birth defect. Children with upper and lower limb reduction defects may have problems with motor skills, limitations of movements, and emotional issues brought on by the public. Treatment for a birth defect like this deals with giving the child access to a functional limb that he or she can use for daily life. This can include prosthetic extremities, splints/braces, surgery, and rehabilitation.
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