Lecture 1: Introduction and Definitions

Question 1

Acquired

Answer 1

Somatic change occuring after birth, usually cancer related.

Question 2

Allele

Answer 2

Particular copy of agene on a chromosome.

Question 3

AMA

Answer 3

Advanced maternal age.

Question 4

Anticipation

Answer 4

The tendency of certain disorders to appear at earlier ages and/or with increased severity in successive generations.

Question 5

cfDNA

Answer 5

Cell free DNA– fragments of DNA found in the serum of blood.

Question 6

Chimera

Answer 6

Cell lines from two individuals (bone marrow transplant.

Question 7

Compound Heterozygote

Answer 7

An individual with two different abnormal alleles at one locus (i.e. two different disease-causing mutations in the same gene on different chromosomes).

Question 8

Congenital

Answer 8

Present at birth (clinical genetics term.

Question 9

Cosanguinity

Answer 9

Being related by blood to one’s reproductive partner (i.e. cousins who have children together).

Question 10

Constitutional

Answer 10

Present at birth, usually in all cells (cytogenetic term).

Question 11

CVS

Answer 11

Chorionic villus sampling - a prenatal diagnosis.

Question 12

Epigenetics

Answer 12

Something which changes gene expression without altering the DNA sequence (i.e. methylation).

Question 13

FTT

Answer 13

Failure to thrive – doesn’t put on weight, etc.

Question 14

Genotype

Answer 14

Genetic makeup of an individual.

Question 15

Germline

Answer 15

Occuring in the cells of the gonads.

Question 16

Hemizygous

Answer 16

Males are hemizygous with respect to genes on the X chromosome (rather than homozygous or heterozygous) since they have only one X.

Question 17

Heterozygous

Answer 17

The alleles at a specific locus are different (Aa).

Question 18

Homozygous

Answer 18

Both alleles at a specific locus are the same (AA or aa).

Question 19

Hypertelorism

Answer 19

Widely-spaced eyes.

Question 20

Inherited

Answer 20

Passed on from a parent.

Question 21

Karyotype

Answer 21

The number and appearance of chromosomes in the cell nucleus.

E.g. 46,XX or 46XY

Question 22

Locus

Answer 22

The site (location) on the chromosome at which a gene is located (plural: loci)

Question 23

MoM

Answer 23

Multiples of the mean – a measure used in prenatal testing.

Question 24

Mosaic

Answer 24

Two or more cell lines derived from the same individual.

Question 25

MRI

Answer 25

Magnetic Resonance Image.

Question 26

Obligate Carrier

Answer 26

Parent of a child with a recessive condition.

Question 27

Pathogenetic

Answer 27

Change that results in disease.

Question 28

Penetrance

Answer 28

The proportion of individuals who have a known gene mutation who express any of the clinical symptoms associated with the disorder.

Question 29

PGD

Answer 29

Preimplantation genetic diagnosis.

Question 30

Phenotype

Answer 30

Outward appearance of an individual.

Question 31

SAB

Answer 31

Spontaneous abortion, or miscarriage.

Question 32

Somatic

Answer 32

Occurring in all cells, excluding the gonads.

Question 33

Trimester

Answer 33

A division of pregnancy.

First: Weeks 1 - 13
Second: Weeks 14 - 26
Third: Weeks 27 -40

Question 34

US

Answer 34

Ultrasound

Question 35

Variable Expressivity

Answer 35

The same genetic condition can present with different clinical symptoms (phenotypes) in different individuals, even in individuals with identical mutations (genotypes)