Genetics

autosomal dominant - chances of passing to offspring? - sex specific? - consecutive or skipped generations? - do unaffected parents transmit? - if one parent affected and other unaffected, what percent of offspring predicted to be affected?

- 50% chance of passing this to offspring 1.) usually appears in both sexes with equal frequency 2.) both sexes transmit the trait to their offspring (not gender specific) 3.) does not skip generations (seen in consecutive generations) 4.) affected offspring must have an affected parent unless they possess a new mutation 5.) When one parent is affected (heterozygous) and the other parent is unaffected, approximately half of the offspring will be affected 6.) Unaffected parents do not transmit the trait

Nursing role with genetics

- Keep up to date with current treatments and advancements in genetics - work with other healthcare providers in the circumstances of genetic disorders - ask about patient family history

Role of genetics in healthcare (FYI slide)

- genetics have a relatively newer role in healthcare - improving our knowledge of genetics has led to greater knowledge of disease - there are multiple ways to utilize genetics; including health promotion, disease prevention, and individualized treatment plans

Current advancements in genetic testing and their impact

- genomic sequence cost lowered (can now sequence a genome for $1000) - genetic testing available to the public (23 and me) - most genetic testing finds RISKS, not cures or definitive diagnosis

Y-linked - what gender affected? - passed from ________ to ___ - consecutive or skipped generations?

- only males are affected - passed from father to son - does not skip generations

Genomics in healthcare

- preconception/prenatal testing - newborn screens - disease susceptibility (i.e. BRCA 1/2) - screening, diagnosis, and monitoring of disease - prognosis and therapeutic decisions

What is a pedigree? - family record - helps diagnose - helps map / isolate genes - rule out but not necessarily prove a pattern of inheritance

- provides concise and accurate records of families - helpful in diagnosing and following heritable traits (ex. diseases, medical records) - helpful for mapping and isolating genes "responsible" for certain traits or diseases - rule out but don't necessarily prove a certain pattern of inheritance

Purposes of genetic testing

1. determine carrier 2. diagnostic testing (pre-symptomatic, symptomatic, predisposition) 3. benefits 4. risks

Mitochondrial - gender specific? - passed from mom or dad? - affects what percent of children? - affected ______ (male/female) do not transmit any of the trait to their progeny

1.) both males and females are affected 2.) the trait is passed from an affected mother to all her progeny 3.) affected males do not transmit the trait to any of their progeny

Q3: The frequency of expression of an allele when it is present in the genotype of an individual is known as the? A. Penetrance B. Association C. Expressivity D. Homogeneity

A

Q1: Genetic testing was done on a child for a specific disease. The results were positive, meaning at least one parent had passed the gene to the child. Both parents were tested, and results showed that both parents are carriers. Which disease would you expect to have a 100% chance of occurring? A. Parkinsons B. Tay Sachs C. Age-Related Macular degeneration D. Breast Cancer

B. Tay Sachs- autosomal recessive inheritance Parkinson's = 10% genetic; mostly idiopathic Macular degeneration = may have genetic component Breast cancer = usually environmental; 5-10 percent breast cancers are genetically passed down

Q4: The varying degree to which a specific phenotype is displayed is called the? A. Penetrance B. Association C. Expressivity D. Homogeneity

C

Q2: Which statement made by a parent indicates correct understanding of autosomal recessive genetic disorders? A. They affect males greater than females B. Affected males can only have carrier daughters C. An affected child will always have an affected parent D. They affect males and females equally

D

Do case study on slides 22-24

Do case study on slides 22-24

X-linked recessive (or dominant) - sex dependent? - can it be passed from father to son? - does transmission from father go to all daughters? - female carriers have ___% chance of passing gene to children - how many x chromosomes to be expressed in females? how many x chromosomes to be expressed in males? - who is affected more: male or female? - consecutive generations or skipped? - all daughters of carrier mothers will be normal, but ____ will be carriers.

Mutant gene is on x chromosome: male 25% chance of having; female 25% chance of being a carrier. Any male affected in extended family gets x gene from carrier mother will be affected or condition is more severe in male eg. Colorblindness; hemophilia A and B, Duchenne MD, Incidence of trait is greater among males than females in a family Cannot be passed down from father to son Transmission is from father to all daughters (who will be carriers) Female carriers have a 50% risk of passing gene to their children Sex linked single gene traits require that the gene allele be present on both of the x chromosomes for the trait to be expressed in females, and only on one x chromosome for trait to be expressed in males. 1.) usually more males than females are affected 2.) affected sons are usually born to unaffected mothers; thus, the trait skips generations 3.) approximately half of a carrier (heterozygous) mother's sons are affected 4.) never passed from father to son 5.) all daughters of affected fathers are carriers 6.) all sons of affected mothers will be affected 7.) all daughters of carrier mothers will be normal, but half will be carriers

autosomal recessive - chances of affecting offspring? - sex specific? - consecutive or skipped generations? - if offspring affected, are parents affected? - what type of children most often affected (hint. consanguine)

Not found in every generation; sometimes only affects one family member, both male and females can be affected; usually passed on by 2 carriers if 2 carriers one is affected in four; 2 copies of gene needed. 25% of family will be affected, but children of two affected parents will always be affected (risk is 100%), trait is found about equally in male and female members of the same family. Eg. PKU, CF, sickle cell, albinism, alpha-antitrypsin deficiency, 1.) usually appear in both sexes with equal frequency 2.) tends to skip generations 3.) affected offspring are usually born to unaffected parents 4.) when both parents are heterozygous, approximately one-fourth of the offspring will be affected 5.) appears more frequently among the children of consanguine marriages

Multifactorial

Set pattern is not evident; multiple individuals are affected in multiple generations. Combo of genetic and environmental factors( diet, activity, exposure) result in susceptibility to a disorder or illness. Eg. obesity, diabetes Type I, cardiovascular dz, Alzheimer's, autoimmune disorders, Schizophrenia, HTN, Rheumatoid arthritis,BiPolar)

True or false? Ashkenazi jewish people are more likely to have certain cancers.

True

True or false? Mediterranean people are more likely to have thalassemia.

True

Expressivity definition

The degree a trait shows; helps describe individual variability ***Degree to which a person with a specific genotype is affected (how serious the illness may be) Marfan syndrome is an example of this variability

What is incomplete penetrance?

When the genotype is present but the phenotype is not

Genetic transmission definition

transfer of genetic information from genes from one generation to another

Penetrance definition

frequency of expression of a allele when it is present in the genotype ***Proportion of individuals who have the genotype and actually manifest the disease. (If you have the gene, how likely you are to get the illness)

Genotype definition

genetic constitution

Association definition

genetic variant associated with a specific disease/trait

Phenotype definition

observable characteristics (i.e. big ears)

pedigree

purpose to recognize patterns of inheritance and determine genetic risks