Genetics part 1

Question 1

What is genetics?

Answer 1

Study of individual genes and their effects on relatively rare, single-gene disorders

Question 2

What is genomics?

Answer 2

Study of all the genes in the human genome together, including their interactions with each other, the environment, and the influence of other psychosocial factors and cultural factors

Question 3

What do these studies [genetics and genomics] allow us to do?

Answer 3

Allows us to predict susceptibility, onset, progression, and response to treatment for many hereditary diseases

Question 4

How many genes are in the human genome?

Answer 4

20,500

Question 5

What does gene therapy do?

Answer 5

• corrects defective genes that are responsible for disease development.
• Involves inserting a healthy copy of the defective gene into the somatic cells of the affected individual.
• Diseases that could be treated with this range from hemophilia and other single-gene disorders to complex disorders such as cancer

Question 6

What are the reasons patients decide either to be tested or not tested?

Answer 6

-Seldom autonomous
-Based on feelings of and commitment to others
-Socioeconomic factors
-Cultural and ethnic differences
-Gap in ability to diagnose and ability to
treat

Question 7

How should genetic history be obtained for genetic counseling in pregnancy?

Answer 7

Questionare or checklist

Question 8

What is the goal of genetic counseling?

Answer 8

The goal is to identify a risk.

Question 9

What is an occurrence risk?

Answer 9

Parents are known to be at risk for producing a child with disease; what’s the risk of their child having the disease?

Question 10

What is a recurrence risk?

Answer 10

Once they have produced a child with disease, what’s the chance their next child will also have the disease?

Question 11

Interpretation of risks?

Answer 11

very personal decision-making process for parents

Question 12

What kind of screenings fall under population based screening?

Answer 12

Newborn screening for phenylketonuria [PKU]

Question 13

What is predictive testing/screening?

Answer 13

it is used to clarify the genetic status of asymptomatic family members

Question 14

What are the two types of predictive testing?

Answer 14

Presymptomatic testing

Predispositional testing

Question 15

What is presymptomatic testing?

Answer 15

if the gene mutation is present, symptoms of the disease are certain to appear if the individual lives long enough. (i.e Huntington’s Disease)

Question 16

What is predispositional testing?

Answer 16

BRCA 1 gene, a positive does not indicate a 100% risk for developing the condition (breast cancer)

Question 17

What are prenatal tests used for?

Answer 17

used to identify the genetic status of a fetus at risk for a genetic condition (done in 1st trimester)

Question 18

What is maternal serum screening?

Answer 18

Maternal serum screening: a blood test used to see if a pregnant woman is at increased risk for carrying a fetus with a neural tube defect (NTD) or chromosomal abnormalities (Down syndrome, Trisomy 18 or Trisomy

Question 19

What is a fetal ultrasound?

Answer 19

Imaging of the fetus inside the uterus obtained by using high-frequency sound waves. Can screen for physical features associated with genetic abnormalities

Question 20

What is amniocentesis and when is it done?

Answer 20

Invasive procedure that obtains fetal DNA from amniotic fluid; after 15 weeks gestation

Question 21

What is chorionic villus sampling and when is it done?

Answer 21

invasive procedure obtaining fetal DNA from chorionic villi; before 15 weeks gestation

Question 22

What are alleles?

Answer 22

genes that code for variations of the same trait…hair color, eye color, etc

Question 23

What is a karyotype?

Answer 23

A pictorial analysis of the number and size of an individual’s chromosomes

Question 24

What is a pedigree chart?

Answer 24

Way to show the inheritance pattern of a trait or illness

Question 25

What are chromosomal abnormalities?

Answer 25

A major cause of reproductive loss, congenital problems, and gynecologic disorders

Can occur during mitosis (somatic cell-autosomal disorders) or meiosis (sex cells-sex-linked disorders)

Question 26

Type of autosomal chromosomal abnormality

Answer 26

Downs syndrome (trisomy 21)

Question 27

What is trisomy 18?

Answer 27

Edwards’ Syndrome

Severe to profound intellectual disability

Most don’t survive to their 1st birthday

Question 28

What are the types of chromosomal abnormalities in regards to sex chromosomes?

Answer 28

Turner syndrome

Klinefelter syndrome

Question 29

What is Turner syndrome?

Answer 29

Monosomy x

Most common deviation in females

Short in stature and webbing of neck,

low hairline; intelligence may be impaired

Question 30

What Klinefelter syndrome?

Answer 30

Trisomy xxy
Most common deviation in males
Affected males have poorly developed secondary sexual characteristics and small testes. Usually infertile, usually tall and may be slow to learn

Question 31

What are autosomal dominant inheritance disorders and give examples.

Answer 31

An affected parent who is heterozygous for the trait has a 50% chance of passing the variant allele to each offspring. No skipping of generations.

Huntingtons disease, Marfan syndrome

Question 32

What are autosomal recessive inheritance disorders and give examples.

Answer 32

Both genes of a pair associated with the disorder must be abnormal for the disorder to be expressed. The chance of the train occurring in each child is 25%

Examples: Cystic fibrosis, sickle cell

Question 33

When do inborn errors of metabolism occur?

Answer 33

Occur when a gene mutation reduces the efficiency of encoded enzymes to a level at which normal metabolism cannot occur.

Defective enzyme action interrupts the normal series of chemical reactions from the affected point onward (PKU

Question 34

Type of x-linked dominant disorders?

Answer 34

fragile x syndrome

rett syndrome

Question 35

multifactorial genetic malfunction?

Answer 35

Combination of environmental and genetic factors

Cleft lip and palate
Congenital heart disease
Neural tube defects
Pyloric stenosis