Normal Prenatal Development Occurs in 95 to 98% of All

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The Answer is Students' answers may vary.Some of the genetic or chromosomal abnormalities are listed below.
Genetic/chromosomal abnormalities
Phenylketonuria (PKU)-a child born with the inherited disease phenylketonuria cannot produce an enzyme that is required for normal development.This deficiency results in an accumulation of poisons that eventually cause profound intellectual disability.
Sickle-cell anemia-about 10% of the African-American population can pass on sickle-cell anemia,a disease involving abnormally shaped red blood cells.Children with the disorder have episodes of pain,yellowy eyes,stunted growth,and vision problems.
Tay-Sachs disease-it is mostly found among Jews of Eastern European ancestry.The body is unable to break down fat when afflicted with Tay-Sachs disease.The child usually dies by the age of 3 or 4 years.
Down syndrome-it occurs when a zygote receives an extra chromosome at conception.It is one of the causes of intellectual disability.Mothers older than 35 or younger than 18 are at higher risk of giving birth to children with Down syndrome.
Some of the teratogens associated with birth defects are:
Mother's nutrition-Undernourished mothers may give birth to underweight babies who are susceptible to disease.
Mother's illness-Rubella,syphilis,diabetes,and high blood pressure may produce a permanent effect on the fetus if they occur early in the pregnancy.HIV may be passed from mother to child prenatally.
Mother's emotional state-Mothers who are tense and anxious late in their pregnancy may have irritable infants who eat and sleep poorly.
Mother's use of illegal drugs (e.g. ,cocaine,heroin,methamphetamine)-babies may be born addicted to the drug and undergo painful withdrawal.Permanent physical and mental impairments may result.
Alcohol-1 out of every 750 infants is born with fetal alcohol syndrome (FAS),a condition resulting in below-average intelligence,slowed growth,and facial deformities.In a condition known as fetal alcohol effects (FAE),children display some but not all of the problems of FAS.
Nicotine-increased risk of miscarriages and heightened infant mortality.

Normal Prenatal Development Occurs in 95 to 98% of All

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