Description: No melanin; person is very blond, pale
Prognosis: Normal, but must avoid sun damage
Probable Inheritance: Recessive
Incidence*: Carriers more common among Native Americans and African Americans
Carrier Detection?: No
Prenatal Detection?: No

Description: Memory loss; increasing mental impairment
Prognosis: Eventual death, often after years of dependency
Probable Inheritance: Early onset—dominant; after age 60—multifactorial
Incidence*: Fewer than 1 in 100 early onset; more common in late adulthood
Carrier Detection?: Yes, for early onset; yes, for risk factors
Prenatal Detection?: No

Description: Tumors that can spread
Prognosis: Each type has different rates of cure and fatality
Probable Inheritance: Multifactorial; almost all cancers have a genetic component
Incidence*: Most people eventually develop some type; about one-fourth die
Carrier Detection?: No
Prenatal Detection?: No

Description: The two sides of the upper lip or palate are not joined
Prognosis: Correctable by surgery
Probable Inheritance: Multifactorial
Incidence*: 1 in every 700 births; more common in Asians and Native Americans
Carrier Detection?: No
Prenatal Detection?: Yes

Description: The foot and ankle are twisted
Prognosis: Correctable by surgery
Probable Inheritance: Multifactorial
Incidence*: 1 in every 200 births; more boys than girls
Carrier Detection?: No
Prenatal Detection?: Yes

Description: Mucous obstructions, especially in lungs, stomach
Prognosis: Most live to middle adulthood
Probable Inheritance: Recessive gene; also spontaneous mutations
Incidence*: 1 in 3,200; 1 in 25 European Americans is a carrier
Carrier Detection?: Sometimes
Prenatal Detection?: Yes, in most cases

Description: Inability to hear
Prognosis: Language possible via signs, or cochlear implants
Probable Inheritance: Multifactorial; some forms are recessive
Incidence*: 1 in 1,000 births; more common in people from Middle East
Carrier Detection?: No
Prenatal Detection?: No

Description: Abnormal sugar metabolism; insufficient insulin
Prognosis: Early onset (type 1) fatal without insulin; later onset (type 2), variable
Probable Inheritance: Multifactorial; for later onset, body weight is significant
Incidence*: Type 1: rare; type 2: 1 in 6, especially non–European Americans
Carrier Detection?: No
Prenatal Detection?: No

Description: Absence of clotting factor in blood
Prognosis: Death from bleeding; blood transfusions prevent damage
Probable Inheritance: : X-linked recessive; also spontaneous mutations
Incidence*: 1 in 10,000 males; royal families of Europe had it
Carrier Detection?: No
Prenatal Detection?: No

Description: Obstruction causes excess fluid in the brain
Prognosis: Brain damage and death; surgery allows normal life
Probable Inheritance: Multifactorial
Incidence*: 1 in every 100 births
Carrier Detection?: No
Prenatal Detection?: Yes

Description: Weakening of muscles
Prognosis: Inability to walk, move; wasting away; death
Probable Inheritance: Recessive or multifactorial
Incidence*: 1 in every 3,500 males develops Duchenne’s
Carrier Detection?: Yes, for some forms
Prenatal Detection?: Yes, for some forms

Description: Anencephaly (parts of the brain missing) or spina bifida (lower spine not closed)
Prognosis: Anencephalic—severe retardation; spina bifida— poor lower body control
Probable Inheritance: Multifactorial; folic acid deficit and genes
Incidence*: 1 in 1,000 (anencephaly); 3 in 1,000 (spina bifida); more common in Welsh, Scots
Carrier Detection?: No
Prenatal Detection?: Yes

Description: Abnormal digestion of protein
Prognosis: Mental retardation, preventable by diet begun soon after birth
Probable Inheritance: Recessive
Incidence*: 1 in 100 European Americans is a carrier; higher among Irish, Norwegians
Carrier Detection?: Yes
Prenatal Detection?: Yes

Description: Overgrowth of muscle in intestine
Prognosis: Vomiting, weight loss, death; corrected by surgery
Probable Inheritance: Multifactorial
Incidence*: 1 boy in 200, 1 girl in 1,000; less in African Americans
Carrier Detection?: No
Prenatal Detection?: No

Description: Neurological developmental disorder
Prognosis: Boys die at birth; at 6–18 months, girls lose speech and motor skills
Probable Inheritance: X-linked
Incidence*: 1 in 10,000 female births
Carrier Detection?: No
Prenatal Detection?: Sometimes

Description: Severely distorted thought
Prognosis: Drugs, therapy ease symptoms
Probable Inheritance: Multifactorial
Incidence*: 1 in 100 people develop it by early adulthood
Carrier Detection?: No
Prenatal Detection?: No

Description: Abnormal blood cells
Prognosis: Painful “crisis”; heart, kidney failure; treated with drug
Probable Inheritance: Recessive
Incidence*: 1 in 11 African Americans and 1 in 20 Latinos are carriers
Carrier Detection?: Yes
Prenatal Detection?: Yes

Description: Enzyme disease
Prognosis: Healthy infant becomes weaker, usually dying by age 5
Probable Inheritance: Recessive
Incidence*: 1 in 30 U.S. Jews and 1 in 20 French Canadians are carriers
Carrier Detection?: Yes
Prenatal Detection?: Yes

Description: Abnormal blood cells
Prognosis: Low energy, vulnerable to infections, slow growth
Probable Inheritance: Usually recessive, occasionally dominant
Incidence*: 1 in 10 from Italy, Greece, India, Egypt is a carrier
Carrier Detection?: Yes
Prenatal Detection?: Yes

Description: Uncontrollable tics, body jerking, verbal outbursts
Prognosis: Appears at about age 5; worsens, then improves
Probable Inheritance: Dominant, but variable penetrance
Incidence*: 1 in 250 children
Carrier Detection?: Sometimes
Prenatal Detection?: No