13 - Congenital Disorders Flashcards
Congenital defect
present at birth or shortly afterwards including inherited disorders and developmental disorders
causes of congentital defects
- genetic factors
- environmental factors during embryonic or fetal development
- rarely - intrauterine factors
chromosomal disorders
error during meiosis, common cause of spontaneous abortion
multifactorial disorders
can be polygenic (multiple genes) or inherited tendency combines with environmental factors
autosomal recessive disorders
both parent must pass on the allele, can be affected or carriers
Cystic fibrosis, PKU, Tay-Sachs
autosomal recessive disorders
Autosomal dominant disorders
inheritance of one allele causes disorders, only one parent needs to carry allele - no carriers
Autosomal dominant disorder examples
huntington’s, polycystic kidney disease, marfans, hypercholesterolemia
X linked recessive disorders
allele carried on X chromosome not Y, heterozygous females are carriers, homozygous recessive may be affected, inheritance can skip generations
X linked recessive manifested in
heterozygous males lacking the matching unaffected gene on Y chromosome
X linked examples
Duchenne’s muscular dystrophy, hemophilia
Fragile X syndrome
most common genetic cause of cognitive defects, effects are variable
Environmental agent that produces abnormalities during embryonic or fetal development
teratogenic agent
Teratogenic agents
radiation, drugs, infectious agents. ToxoplasmosisOtherRubellaCysomegalovirusH erpes simplex infections
Methods of prenatal testing
- ultrasonography: nuchal translucency (neck)
- maternal serum screening (AFP, hCG, Estriol)
- amniocentesis
- CVS
- PUBS
- cell free DNA
