Human Genetic Disorders

Recall:   Autosome - any

chromosome other than the X & Y (humans have 22 pairs of autosome + 1 pair of sex chromosomes)

Autosomal Recessive Disorders Most affected

children have unaffected parents

Heterozygotes (carriers) are unaffected

Autosomal Recessive DisordersTay - Sachs Disease More common

among Jewish populations

Young children begin showing signs of slowed development

Severe impairment and death

Build up of lipids in the body – lysosomes do not function properly

Autosomal Recessive Disorders

Cystic Fibrosis More common in

Caucasians Mucus in

respiratory tract, difficulty breathing

Extreme salty sweat

Mucus may cause secondary infections

Autosomal Recessive Disorders

Phenylketonuria (PKU) Lack enzyme for

normal metabolism Phenylalanine builds

up and causes brain damage

Newborns are routinely tested

Changes in diet lead to normal life

PKU

Can be managed if caught early

Autosomal Recessive Disorders

Sickle Cell Disease More common

in Africans (African-Americans)

Causes blood to be sickle shaped

Affects oxygen flow to organs, causing weakness, pain, anemia, etc

Heterozygotes are resistant to malaria

Sickle-Cell Anemia

Autosomal Dominant Disorders

Affected children usually have an affected parent

Heterozygotes are effected

Two heterozygotes (Hh x Hh) can produce a normal (hh) child

Autosomal Dominant DisordersHuntington Disease Neurological disorder, progressive

degeneration of the brain Symptoms appear later in life (40s,

50s)

Huntington’s Disease

Huntington’s Disease

Autosomal Dominant Disorders

Achondroplasia Common form of Dwarfism Short arms and legs, normal

torso Homozygotes (AA) do not

survive

Achondroplasia

HDLs vs. LDLs

Autosomal Dominant DisorderHypercholesterolemia Incomplete dominance Caused by a recessive allele, however in

the heterozygous form (Hh), individuals have 2x the normal blood cholesterol levels

Can lead to Atherosclerosis