19 - Birth Defects

Question 1

What are four causes of birth defects?

Answer 1

1. Genetic
2. Teratogenic
3. Multifactorial
4. Unknown

Question 2

What is considered full term?

Answer 2

37 weeks or longer.

Question 3

What are clinical features of trisomy 21?

Answer 3

Epicanthal folds, small and low set ears, simian crease, hypotonia, PDA (patent ductus arteriosus), hirschsprungs, duodenal atresia, and redundant skin folds on neck.

Question 4

What is the incidence of trisomy 21?

What are some risk factors?

Answer 4

1:800-1000 live births.

Advanced maternal age (<35) and translocations.

Question 5

How can trisomy 21 be detected in the 1st and 2nd

Answer 5

1st trimester: ultrasound nuchal fold, harmony blood test (detects tri21 or tri18)

2nd trimester: Quad screen (estriol, hCG, inhibin-A, AFP), amniocentesis.

Question 6

What are the long-term complications of trisomy 21?

Answer 6

Mental deficiency, developmental delays, hearing loss, Alzhiemer’s, seizures, atlanto-axial instability (C1), hypothyroidism, and leukemia.

Question 7

What is Trisomy 13? What are characteristics?

Answer 7

Patau’s syndrome; lethal.

Microcephaly, micropthalmia, cleft life/palate, hearing loss, polydactyly, clenched hands.

Palliative delivery can be done.

Question 8

What is trisomy 18? What are the characteristics?

Answer 8

Edward’s syndrome; lethal.

Low-set ears, clenched hands, hypoplastic nails, umbilical hernia, rocker bottom feet(prominent heel), cardiac defects.

Question 9

Fetal alcohol syndrome is a _______ birth defect.

Answer 9

Teratogenic.

Alcohol is a teratogen.

Question 10

What is the difference between fetal alcohol syndrome and effect? What is the prevalence of each?

Answer 10

Effect - one symptom; 1 in 100 children

Syndrome - all of the symptoms; 5-3 per 1,000 live births

Question 11

What are the characteristics of a baby with fetal alcohol syndrome?

Answer 11

Mental retardation, learning and emotional problems, growth deficiency, nervous system dysfunction, social adaption problems, and higher incidence of mental health problems.

1 in 100 have the Effect
.5-3 per 1,000 live births have the Syndrome.

Question 12

What are the facial characteristics of fetal alcohol syndrome?

Answer 12

Short nose, indistinct philtrum (lines between nose and upper lip), thin upper lip, and flat midface.

Small and narrow heads.

Question 13

What is thalidomide?

Answer 13

A drug (teratogen) used in the 40’s and 50’s to treat nausea that causes a defect in the long bones of limbs causing limb defects.

Question 14

What is DES and what does exposure cause?

Answer 14

A derivative of estrogen used to prevent miscarriage and premature labor.

Female babies went on to have abnormal vaginal tumors and T-shaped uterus.

Male babies went on to have higher risk of testicular cancer.

Question 15

What is the main cause if ambiguous genitalia? How is it inherited and how is this detected?

Answer 15

Congenital adrenal hyperplasia (CAH); autosomal recessive inheritance.

Included in the WI newborn screening.

Question 16

What causes congenital adrenal hyperplasia (CAH)? Which is the most common?

Answer 16

21-hydroxylase deficiency accounts for >90% of all cases and is what’s screened for in newborns. Causes accumulation of precursors that’s shunted into the androgen synthetic pathway.

Teratogenic exposure.

Question 17

Describe the effects on CAH on males vs females?

Answer 17

90% are females that are masculinized.

Early post-natal virilization in males. In 75% of the newborn boys, a “salt-losing syndrome” may be the only finding.

Adrenocortical insufficiency and salt-losing crises can occur in both genders.

Question 18

What can be caused by the increase in androgen secretion in children with CAH?

Answer 18

Accelerated early growth with premature fusion of epiphyses and ultimate short stature.

Question 19

How can CAH be treated?

Answer 19

Glucocorticoids replace the cortisol and suppress the excessive corticotropin production.

Salt-wasters and those with high plasma renin may also need mineralocorticoids.

Question 20

What is CHARGE syndrome? What type of birth defect is it?

Answer 20

Multifactorial

Colobomas
Heart Defects 
Atresia choanae
Retarded growth 
Genital anomalies 
Ear anomalies

Question 21

What is the genetic cause CHARGE syndrome? How is it inherited?

Answer 21

CHD7 gene mutation accounts for 50% of cases.

Autosomal dominant.

Question 22

What is VACTERL association? What type of birth defect is it?

Answer 22

Multifactorial, called association because genetic cause unknown.

Need at least 3 from the following (midline defects): 
Vertebral anomalies
Anal atresia 
Cardiac anomalies 
Tracheo-esophageal atresia 
Esophageal atresia 
Renal anomalies 
Limb anomalies