10. Abnormalities, Variation & Mutation

ABNORMALITIES: Variation & Mutation

Mutations 1. 2. 3. 4. 5.

Somatic vs. Gametic Spontaneous vs. induced Random vs. irreversible Suppressor mutation Point (base substitution) vs. Frameshift (indel) 6. Transversion and Transition 7. Missense, Nonsense and Neutral 8. Repair of mutations

Classify the following MUTATIONS

Genetic diseases The following are the different types of genetic

diseases: chromosomal abnormalities single gene defects multifactorial problems teratogenic problems

Types of Chromosomal mutations

Genetic diseases – Chromosomal abnormalities  Chromosomal abnormalities in the baby may be inherited from the parent or may occur with no family history. The following chromosomal problems are the most common:

aneuploidy - more or fewer chromosomes than the normal number, including:

 Down syndrome (trisomy 21) - cells contain three #21

chromosomes.

 Turner syndrome - one of the two sex chromosomes is not

transferred, leaving a single X chromosome, or 45 total.

 deletion - part of a chromosome is missing, or part of the

Genetic diseases – Chromosomal abnormalities  translocation - a rearrangement of a chromosome segment from one location to another, either within the same chromosome or to another.

 balanced translocation - the DNA is equally exchanged

between chromosomes and none is lost or added. A parent with a balanced translocation is healthy, but he/she may be at risk for passing unbalanced chromosomes in a pregnancy.

 Robertsonian translocation - a balanced translocation in which

one chromosome joins the end of another.

 mosaicism - the presence of two or more chromosome

patterns in the cells of a person, resulting in two or more cell

Genetic diseases – single gene dominant - an abnormality occurs when only one

of the genes from one parent is abnormal. If the parent has the disorder, the baby has a 50 percent chance of inheriting it. Examples include the following:  achondroplasia - imperfect bone development

causing dwarfism.

 Marfan syndrome - a connective tissue disorder

causing long limbs and heart defects.

Genetic diseases – single gene recessive - an abnormality only occurs when both parents have abnormal genes. If both parents are carriers, a baby has a 25 percent chance of having the disorder. Examples include the following:  cystic fibrosis - a disorder of the glands causing excess

mucus in the lungs and problems with pancreas function and food absorption.

 sickle cell disease - a condition causing abnormal red blood

cells.

 Tay Sachs disease - an inherited autosomal recessive

Genetic diseases – single gene X-linked - the disorder is determined by genes on the X chromosome. Males are mainly affected and have the disorder. Daughters of men with the disorder are carriers of the trait and have a one in two chance of passing it to their children. Sons of women who are carriers each have a one in two chance of having the disorder. Examples include the following:

 Duchenne's muscular dystrophy - a disease of muscle

wasting.

 hemophilia - a bleeding disorder caused by low levels,

Genetic diseases multifactorial

due to several problems, or a combined effect

of genes and the environment. It is difficult to predict inheritance of abnormalities caused by multiple factors. Examples include heart defects, cleft lip or cleft palate, and neural tube defects (defects in the spine or brain).

Genetic diseases teratogenic certain medications (always consult your physician before taking any medications during pregnancy) alcohol high level radiation exposure lead certain infections (such as rubella)

ASSIGNMENT

Examples of Genetic Diseases With complete mechanism and explanation 2 per person