Answer
Four important causes of birth defects are drugs-- for example, thalidomide; alcohol ; radiation, for example,rays); genetic causes , for example, mutations and aneuploidy;
Thalidomide is well known to cause limb malformations and non development( absence)
Alcohol may cause fetal alcohol syndrome(FAS). which may express as microcephaly, and failure to
grow normally
Radiation , for example x-rays, and nuclear radiation; radiation my cause childhood cancer, failure
to grow, mental retardation, microcephaly
Infectious diseases present during pregnancy( herpes simplex, cytomegalovirus, toxoplasmosis,
syphilis and gonorrhea) cause many birth defects such as congenital blindness, cerebral palsy,
mental retardation and seizures.
Work Step by Step
Genetic mutations and aneuploidy
3. Achondroplastic dwarfism caused by genetic mutations: expressions include microcephaly( abnormally head);, and childhood cancer.
4 Aneuploidy due to nondisjunction of chromosomes ( failure to separate). Some expressions of non-disjunction include Klinefelter's syndrome (XX/Y), Down's syndrome( trisomy 21) and Turner's syndrome (X/O)
.
