Flashcards in Lect. 19 - Developmental Disorders Deck (27):
What are the approximate percentages of the causes of congenital anomalies?
Multifactorial = 25%
Environmental = 7%
Chromosomal = 10%
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
What are examples of gene mutations?
Phenylketonuria, Galactosemia, and Cystic fibrosis
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
Congenital deficiency of galactoyl-1-phosphate uridyltransferase. Results in tissue accumulation of galactose 1-phosphate.
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.
Deletions, duplications, inversions, trans locations
Changes in chromosome number
Aneuploidy and Euploidy
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
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
What are some infectious agents that can result in birth abnormalities?
Viruses like rubella, herpes, varicella-zoster, influenza, mumps; bacterial infections; protozoans
What are the major risk factors of prematurity?
Preterm premature rupture of placental membranes; intrauterine infections - uterine, cervical, and placental structural abnormalities; multiple gestation
What is the second most common cause of neonatal mortality?
Prematurity and fetal growth restrictions
What are the hazards of prematurity?
Hyaline membrane disease, necrotizing enterocolitis, sepsis, interventricular hemorrhage, long-term complications incl. developmental delay
Fetal factors resulting in fetal growth restriction:
Chromosome disorders, congenital anomalies, congenital infections
Placental factors resulting in fetal growth restriction
Umbilical-placental vascular anomalies; placenta Previa; placental thrombosis and infarction; multiple gestational; placental genetic mosaicism
Maternal factors resulting in fetal growth restriction
Preeclampsia, chronic hypertension, maternal use of drugs, narcotics, alcohol, nicotine, and maternal malnutrition
Hydrops refers to the accumulation of edema fluid in the fetus during intrauterine growth; immune Hydrops and nonimmune Hydrops
What is the cause of immune Hydrops?
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
Explain why Rh disease is not a problem w/ the first pregnancy
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
What is the consequence of Rh disease?
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
What are the major causes of nonimmune Hydrops?
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
Billirubin induced brain defect
Persistent elevated bp (140/190) that develops after 20 weeks of gestation and returns to normal after birth
More serious that pregnancy-induced hypertension; bp is higher, proteinuria, weight gain, edema
Extremely serious condition; extremely high bp; grand mal seizures or coma