Genes & Genetic Mutations

Study of biologic inheritance

Substance giving the nucleus a granular appearance, forms chromosomes

Trisomy 21

Autosomal aneuploidy

• Pregnancy in women older than 35 years

• Flat facial profile

• Growth failure

• Leukemia risks

• Heart problems

• Mental retardation ranges

Both sexes affected equally

Sex aneuploidy

• X, 45

• Short stature

• Webbed neck

• No menstrual cycles

• Broad chest

Females only

Sex aneuploidy

• XXY, 47

• Gynecomastia

• Tall frame

• Wide hips

• Long arms and legs

• No facial hair

Males only

Autosomal deletion (of chromosome 5)

• Crying sounds like a "cat"

• Heart defects

• Microcephaly

• Severe mental retardation

Both sexes

• Huntington disease

• Neurofibromatosis/von Recklinghausen disease

• Marfan's syndrome

Down syndrome (trisomy 21)

*X is always dominant here

• Turner syndrome

• Klinefelter syndrome

• Cystic fibrosis

• Sickle cell disease

• PKU

• Tay-Sachs disease

Hemophilia

Position of a gene

Unit of heredity

Variation of a gene

AA

Aa

aa

23

46

22 autosomes

1 pair (either XX or XY)

The presence of, or absence of one or more chromosomes; does not contain a multiple of 23 chromosomes

Presence of only one copy of any chromosome *LETHAL

A cell containing 3 copies of one chromosome

Cause of an aneuploidy, failure to separate properly during mitosis/meiosis

Percentage of individuals with a specific genotype with expected phenotype; the probability of a trait being expressed

Individual who has a gene for a disease but does not express the disease

Extent of variation in a phenotype associated with a genotype; variation in phenotypic expression

Skip generations

*Autosomal dominant

• Chromosome 4

• Degenerative disorder of the cerebral cortex

• 5 year survival

• CHOREA

*Autosomal dominant

• Chromosome 17

• Cafe au lait

Mating of 2 related individuals

*Autosomal recessive

• Most common in Caucasians

• Defective CFTR gene

• Lungs and digestive tract affected

*Autosomal recessive

• Most common in African Americans

• Deoxygenation in RBCs lead to sickle shape

• Has decreased recently

*X-linked

• Serious bleeding disorder

• Inherited from MOTHER --> SON

*Are recessive disorders

*AFFECTED MOTHER --> SON *AFFECTED FATHER --> ALL DAUGHTERS AFFECTED

Skip generations and have carriers

Both parents are usually heterozygous carriers *Recurrence risk is ~25% for offspring

The probability that an individual will develop a genetic disease

*Ex: Autosomal dominant, 1 parent affected, 1 parent normal = 1/2 for each child