genetics Flashcards
(30 cards)
genetics
The study of heredity and the focus is on SINGLE genes
genomics
study of ALL genes and their inter-relationships and influence on growth and development
Who provides genetic services?
Clinical geneticist
Genetic counselor
Nurse practitioner
Other practitioners: including nurses!
Why perform genetic testing?
- establish or confirm a diagnosis
- Reproductive decision making, carrier testing, and fetal testing (CF)
- Predict risk for future disease (breast cancer/ huntingtons)
- Aid in management decisions
- Can provide personalized care
cancer genetics can:
Identify who will benefit from high-risk intervention
Individualize screening based on mutation status and family history
Target therapy specifically to the genetic type of cancer
(PARP inhibitors in BRCA carriers, Avoid radiation in TP53 carriers )
human genome project
international 13 year effort to produce a comprehensive sequence of the human genome
Goal: Was to map, sequence, and determine the function of all human genes
genotype
genes inherited from parents
instructions on how the body is supposed to be built and function
phenotype
a person’s entire physical appearance - their outward characteristics
Refers to what you actually see expressed by the genotype. affected by the environment
trisomy
three copies of one chromosome
“better to have extra than less”
down syndrome
trisomy 21
downs
low nasal bridge, epicanthal folds, protruding tongue, poor muscle tone
turner syndrome
Females with only ONE X chromosome (normally have two)
Characteristics:
Absence of ovaries (sterile)
Short stature
Webbing of the neck
Edema
Underdeveloped breasts; wide nipples
Klinefelter Syndrome
Individuals with at least TWO X’s and ONE Y chromosome
Characteristics:
Male appearance
Develop female-like breasts
Small testes
Sparse body hair
Long limbs
Autosomal Dominant Inheritance
Autosomal dominant inherited conditions affect both female and male family members equally and follow a vertical pattern of inheritance.
Only 1 mutated chromosome = disease
50% chance
ex) hereditary breast/ovarian cancer, familial hypercholesterolemia, Huntington’s disease, marfan syndrome, neurofibromatosis, cowden syndrome
aneuploidy
somatic cell that doesnt contain a multiple of 23 chromosomes
monosomy
only one copy of any chromosome
often fatal
disjunction
normal separation of chromosomes during cell division
nondisjunction
usual cause of aneuploidy
failure of homologous chromosomes or sister chromatids to sep normally during meiosis or mitosis
cell free DNA (cfDNA)
prenatal; short fragments of DNA
- take blood sample from mom + test
autosomal aneuploidy
down syndrome
1 in 800 live births
Mentally challenged, low nasal bridge, epicanthal folds,
protruding tongue, poor muscle tone
* Risk increases with maternal age
indications for genetic consult
Developmental Delay
* Intellectual Disability
* Dysmorphic features
* Family History of….
* Failure to Thrive
* Atypical Growth
* Cafe-au-lait macules
* Congenital Defects
* Sensorineural Hearing Loss
* Seizures
* Atypical Sexual Development
DNA
genetic info + decoded by translation into protein
DNA chemical bases: A (adenine), G (guanine), T (thymine), C (cystosine)
3 bases – 1 codon = 1 amino acid
* 2 or more amino acids = peptide
* ~50 or more amino acids = protein
A + T, G + C = complimentary base pairs
cystic fibrosis
most common, deadly, inherited disorder affecting Caucasians (CFTR gene)
1 in 29 caucasian american have defective gene
autosomal recessive - must inherit both defective CF gene
Non-invasive prenatal test (NIPT)
Reports on trisomy 13, 18, and 21
sex chromosome aneuploidies
cowden syndrome
PTEN Gene
Mainly hamartomatous polyps throughout GI tract.
colon cancer risk
risk for thyroid, breast, and endometrial cancers
Characteristic skin findings: macrocephaly, lipoma, fibroma
autosomal recessive inheritance
when a person has two copies of a mutant autosomal gene of a single copy of a mutant X-linked gene in the absence of another X chromosome.
horizontal pattern; single gen relatives
25% chance
ex. CF, galactosemia, PKU, sickle cell anemia, tay-sach, canavan disease, ataxia telangiectasia
