Ch 15 - Developmental Genetics and Birth Defects

percent of infant deaths attributed to birth defects

20%

percent of infant deaths attributed to complications of prematurity

20%

percent of infant deaths attributed to problems in developmental processes

50%

congenital anomalies

major cause of morbidity, intellectual disability, loss of productivity

dysmorphology

study of congenital birth defects that alter the shape or form of one or more parts of the body of a newborn child

5 causes of birth defects

• chromosome imbalance (trisomy)

• copy number variants (del., dup, etc.)

• single gene defects

• teratogen (environment - drugs, chemicals, infections)

• multifactorial (no identifiable cause)

pleiotrophy

the effects of a single-gene on multiple unrelated phenotypic features

two types of pleiotrophy

syndrome or sequence

syndrome pleiotrophy

causative agent causes multiple abnormalities at the same time in multiple organ systems

sequence pleiotrophy

causative agent affects only a single organ system at one time, one malformation cascades into other defects as secondary effects

• multiple structures at different times

the genome is not a master blueprint

• primary source of information that controls and specifies human development

• not a literal description of the final form that all embryological and fetal structures will take