Lect. 19 - Developmental Disorders

Question 1

What are the approximate percentages of the causes of congenital anomalies?

Answer 1

Multifactorial = 25%
Environmental = 7%
Chromosomal = 10%

Question 2

Gene mutations

Answer 2

Include inborn errors of metabolism, which are rare; inherited most commonly as autocomplete recessive or X-linked diseases, a few inherited as dominant traits; often affect enzymes and biochemical pathways

Question 3

What are examples of gene mutations?

Answer 3

Phenylketonuria, Galactosemia, and Cystic fibrosis

Question 4

Phenylketonuria

Answer 4

Congenital deficiency of phenylalanine 4-monooxygenase. Causes inadequate formation of L-tyrosine, elevation of serum L-phenylalanine, excretion of phenylpyruvic acid, and accumulation of phenylalanine

Question 5

Galactosemia

Answer 5

Congenital deficiency of galactoyl-1-phosphate uridyltransferase. Results in tissue accumulation of galactose 1-phosphate.

Question 6

Cystic Fibrosis

Answer 6

Inherited disorder that affects mostly the lungs but also the pancreas, liver, kidneys, and intestine. Inherited in an autosomal recessive manner w/ mutations in both copies of the CT transmembrane conductance regulator protein gene.

Question 7

Chromosome rearrangements

Answer 7

Deletions, duplications, inversions, trans locations

Question 8

Changes in chromosome number

Answer 8

Aneuploidy and Euploidy

Question 9

Aneuploidy

Answer 9

Involves a change in chromosome number beyond the 2N state. 80-90% of fetuses w/ Aneuploidy and other abnormalities of chromosomes die in utero, the majority in the earliest stages of gestation; includes Trisomy 21, 13, Turner syndrome, Poly-X syndrome

Question 10

Euploidy

Answer 10

Involves the addition of a complete set of chromosomes in addition to the diploid 2N stage; often the result of a retention of a polar body or by fertilization by more than one sperm; typically results in early spontaneous abortion

Question 11

What are some infectious agents that can result in birth abnormalities?

Answer 11

Viruses like rubella, herpes, varicella-zoster, influenza, mumps; bacterial infections; protozoans

Question 12

What are the major risk factors of prematurity?

Answer 12

Preterm premature rupture of placental membranes; intrauterine infections - uterine, cervical, and placental structural abnormalities; multiple gestation

Question 13

What is the second most common cause of neonatal mortality?

Answer 13

Prematurity and fetal growth restrictions

Question 14

What are the hazards of prematurity?

Answer 14

Hyaline membrane disease, necrotizing enterocolitis, sepsis, interventricular hemorrhage, long-term complications incl. developmental delay

Question 15

Fetal factors resulting in fetal growth restriction:

Answer 15

Chromosome disorders, congenital anomalies, congenital infections

Question 16

Placental factors resulting in fetal growth restriction

Answer 16

Umbilical-placental vascular anomalies; placenta Previa; placental thrombosis and infarction; multiple gestational; placental genetic mosaicism

Question 17

Maternal factors resulting in fetal growth restriction

Answer 17

Preeclampsia, chronic hypertension, maternal use of drugs, narcotics, alcohol, nicotine, and maternal malnutrition

Question 18

Fetal Hydrops

Answer 18

Hydrops refers to the accumulation of edema fluid in the fetus during intrauterine growth; immune Hydrops and nonimmune Hydrops

Question 19

What is the cause of immune Hydrops?

Answer 19

Blood group incompatibility b/w mother and fetus; fetal RBCs reach the maternal blood stream during last trimester or during childbirth; major factor is the D Ag of the Rh group; ABO incompatibility is generally not a problem, b/c maternal Abs remove any incompatible fetal RBCs that cross the placenta

Question 20

Explain why Rh disease is not a problem w/ the first pregnancy

Answer 20

Rh negative mother and Rh positive baby (so has D Ags) that can cross the barrier but the mother doesn’t have any Abs against Rh Ags so first pregnancy is unharmed

Question 21

What is the consequence of Rh disease?

Answer 21

The mother relations ability to produce Rh Abs so if she has another Rh positive baby her Abs (IgG) will attack the RBCs of the fetus

Question 22

What are the major causes of nonimmune Hydrops?

Answer 22

Cardiovascular defects such as congenital cardiac defects and arrhythmias and chromosomal anomalies like Turner syndrome and trisomy 21 and 18; generally due to the cardiac structural aberrations that accompany these anomilies

Question 23

Kernicturus

Answer 23

Billirubin induced brain defect

Question 24

Pregnancy-induced hypertension

Answer 24

Persistent elevated bp (140/190) that develops after 20 weeks of gestation and returns to normal after birth

Question 25

Preeclampsia

Answer 25

More serious that pregnancy-induced hypertension; bp is higher, proteinuria, weight gain, edema

Question 26

Eclampsia

Answer 26

Extremely serious condition; extremely high bp; grand mal seizures or coma

Question 27

What are the three categories of causes of congenital anomalies?

Answer 27

Genetic, Environmental, Multifactorial