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 100 births

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:

Psychological disorder characterized by 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