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Chapter 21
Congenial & Genetic Disorders
Term | Definition |
---|---|
Male sex chromosome | XY |
Female sex chromosome | XX |
allele | one of two forms of a gene at corresponding sites on a chromosome pair; the code for phenotype or characteristic manifested in an individual |
Multifactorial Disorders | result from a combination of genetic predisposition & exposure to certain environmental factors; ex: cleft lip or palate |
Developmental Disorders | are caused by damage to one or more body structures during embryonic or fetal development, during labor & delivery, or shortly after birth; ex: exposure to radiation during pregnancy, smoking, drugs, viruses |
Chromosomal Disorders | involve an abnormal distribution of the chromosomes or dislocation of a part or loss of a chromosome; ex: down syndrome |
Congenital Disorders | are conditions that are present in the individual at birth but are not necessarily manifested until later in life |
TORCH: prenatal screening test for high-risk maternal infections | T-oxoplasmosis O-ther (hep B, mumps, gonorrhea, syphilis) R-ubella C-ytomegalovirus H-erpes |
Autosomal Recessive Disorders | carrier state; both parents must pass on the defective gene; ex: cystic fibrosis, sickle cell anemia |
X-Linked Recessive Disorders | carrier state; both parents must pass on the defective gene; ex: color blindness, duchenne muscular dystrophy, hemophilia A |
Autosomal Dominant Disorders | no carriers, and unaffected persons do not transmit the disorder; ex: Huntington's |
X-Linked Dominant Disorders | fragile X syndrome; most common cause of mental retardation, cognitive deficit, & learning disorders |
Example of single gene disorders | Autosomal Dominant Autosomal Recessive X-Linked dominant X-Linked Recessive |
Single gene Disorders | are caused by a change in one gene within the reproductive cells (ova or sperm); this mutant gene is then transmitted to subsequent generations following the specific inheritance pattern for that gene |