Environment and Genetics Flashcards
What type of bases is DNA made up of?
Purine Bases (Adenine and Guanine) Pyrimidine bases (Cytosine and Thymine)
What base does Adenine always pair with?
Thymine (replaced by Uracil in RNA)
What does Guanine always pair with?
Cytosine
Define Genetics
The study of the transmission of single genes within families and the analysis of more complex of inheritance
Define Genomics
The study of genes and their function. Genomics aims to understand the structure of the genome, including the mapping genes and sequencing the DNA.
What is the difference between genetics and genomics?
Genomics is better because it is tailored for each person’s unique needs and it can help find a treatment that is maximally effective
How many pairs of chromosomes are there in humans?
23 pairs
How many pairs of autosomes are there in humans?
22 pairs
How many pairs of sex chromosomes are there in humans?
1 pair
What are congenital anomalies or disorders?
disorders present at birth
What are the types of congenital anomalies/disorder?
- single-gene
- chromosomal
- developmental
- Teratogenic
- Multifactoral
Define Single-gene disorders
A trait controlled by one set of alleles that is transmitted to subsequent generations
What do single genes control?
Specific functions (color blindness)
What are the 4 types of single-genes?
- autosomal recessive
- autosomal dominant
- x-linked recessive
- x-linked dominants
What classifies an autosomal recessive disorder?
both parents must pass on the allele for the disorder
What is the term used to define parents who are heterozygous for a disease and unaffected?
Carriers
Are homozygous parents affected?
yes
Give examples of autosomal recessive single-gene disorders
- cystic fibrosis
- PKU
- Tay-sachs disease
What classifies an autosomal dominant disorder?
When the parent has the dominant allele. Only one parent needs to have the allele to pass it on.
Are there any carriers for the autosomal dominant disorders?
No, anyone who has the dominant allele is affected
Why are autosomal dominant disorders termed delayed lethal genotypes?
The allele for the disorder may have been passed on to the next generation before diagnosis of the disease in a parent because symptoms may become evident later in life.
Give examples of Autosomal dominant disorders
- Adult polycystic kidney disease
- Huntington disease
- Familial hypercholesterolemia
- Marfan syndrome
What is Marfan Syndrome?
When someone has long limbs, large hands and feet, and their hearts give out
What classifies an X-linked recessive disorder?
A disorder that comes from the mother’s side. It is manifested in heterozygous males lacking the matching unaffected gene on the Y chromosome. It may appear to skip generations.
Who are the carriers for X-linked recessive disorder?
Heterozygous females
Who are affected by X-linked recessive disorders?
Homozygous recessive females
Give examples of X-linked recessive disorders
Duchenne muscular dystrophy
Classic hemophillia
What are X-linked dominant disorders?
Dominant disorders that are carried from the females
Who are affected by X-linked dominant disorders?
Heterozygous males and females
Give an example of an X-linked dominant disorder
Fragile X syndrome
What is Fragile X syndrome?
The most common genetic cause of cognitive deficits.
The mutation causes the affected X chromosome to appear constricted or broken on a karyotype
When do chromosomal disorders/anomalies occur?
When there is an error during meiosis
What is one of the most common chromosomal disorders?
Down syndrome
What increases the risk of having Down syndrome?
Increasing maternal Age
What screening can be done prior to birth to determine if the fetus has Down syndrome?
- Triple/quad screen test
- first trimester screen test (ultrasound+ maternal blood screening)
- Amniocentesis
- Choronic villous sampling
What are some characteristic in the face of someone who has Down syndrome?
- small head
- round face
- Flat facial profile
- Slanted eyes and epicanthic fold
- large tongue and high-arched palate (causes difficulty feeding as infants)
What are some characteristics of the musculoskeletal system of someone who has Down syndrome?
- Small hands, singular palmar crease
- short stature
- hypotonic muscle and loss joints (Cindy calls them floppy babies)
What are some other characteristics of Down syndrome?
- multiple heart defects
- Delayed developmental stages
- Cognitive impairment
- Delayed or incomplete sexual development (Males =infertile; Females= lower rate of conception)
What are some types of disorders caused by translocation of chromosomes?
- cleft palate
- congenital hip dislocation
- congenital Heart disease
- Type 2 diabetes
- Coronary Artery disease
- Obesity
- High blood pressure
What is a benefit to Disorders caused by translocation of chromosomes?
Sometimes they can be changed by altering lifestyles especially if they are found out early on.
How early can testing be done for genetic disorders?
- prior to conception
- during first trimester of pregnancy
- as a newborn
Who is testing recommended for?
- someone with a family history of a specific disease
- previous birth to a child with abnormality
- Ethnic groups with high risk for a specific disease
- Pregnant women over 35 years of age (AMA= Advanced Maternal Age)
What disease is common in Jewish/Eastern European Families?
Tay-sachs
What are the types of diagnostic tools used?
- Blood tests of a pregnant woman
- In utero testing
- Neonatal testing
- Genogram
Give an example of blood tests for pregnant women
Alpha-fetoprotein testing
Give an example of in utero testing
Amniocentesis
Chorionic villus assay
Give examples of neonatal testing
Excreted metabolites (e.g. PKU) Blood testing
What is diagnostic testing used for?
To confirm a diagnosis based on physical signs
What is predictive testing used for?
to detect gene mutations associated with disorders that appear later in life
What is carrier identification testing used for?
people with a familial history of recessive genetic disorders
What is prenatal testing used for?
To test a fetus when there is a risk of bearing a child with mental or physical disabilities
What is newborn screening used for?
A preventative health measure once the baby is born
What is forensic testing used for?
to identify an individual for legal purposes
What is research testing used for?
for finding unknown genes and identifying the function of a gene
What is pre-implantation used for?
To genetically manipulate the outcome of the possible implanted embryo
Can insurance cover genetic testing?
A lot of times insurance will not cover genetic testing
Can insurance use research genetic testing against you?
No, they have to cover you if you get research genetic testing done and you have to have medical treatment against the disease.
