Lecture 1: Introduction and Definitions Flashcards
Acquired
Somatic change occuring after birth, usually cancer related.
Allele
Particular copy of agene on a chromosome.
AMA
Advanced maternal age.
Anticipation
The tendency of certain disorders to appear at earlier ages and/or with increased severity in successive generations.
cfDNA
Cell free DNA– fragments of DNA found in the serum of blood.
Chimera
Cell lines from two individuals (bone marrow transplant.
Compound Heterozygote
An individual with two different abnormal alleles at one locus (i.e. two different disease-causing mutations in the same gene on different chromosomes).
Congenital
Present at birth (clinical genetics term.
Cosanguinity
Being related by blood to one’s reproductive partner (i.e. cousins who have children together).
Constitutional
Present at birth, usually in all cells (cytogenetic term).
CVS
Chorionic villus sampling - a prenatal diagnosis.
Epigenetics
Something which changes gene expression without altering the DNA sequence (i.e. methylation).
FTT
Failure to thrive – doesn’t put on weight, etc.
Genotype
Genetic makeup of an individual.
Germline
Occuring in the cells of the gonads.
Hemizygous
Males are hemizygous with respect to genes on the X chromosome (rather than homozygous or heterozygous) since they have only one X.
Heterozygous
The alleles at a specific locus are different (Aa).
Homozygous
Both alleles at a specific locus are the same (AA or aa).
Hypertelorism
Widely-spaced eyes.
Inherited
Passed on from a parent.
Karyotype
The number and appearance of chromosomes in the cell nucleus.
E.g. 46,XX or 46XY
Locus
The site (location) on the chromosome at which a gene is located (plural: loci)
MoM
Multiples of the mean – a measure used in prenatal testing.
Mosaic
Two or more cell lines derived from the same individual.
MRI
Magnetic Resonance Image.
Obligate Carrier
Parent of a child with a recessive condition.
Pathogenetic
Change that results in disease.
Penetrance
The proportion of individuals who have a known gene mutation who express any of the clinical symptoms associated with the disorder.
PGD
Preimplantation genetic diagnosis.
Phenotype
Outward appearance of an individual.
SAB
Spontaneous abortion, or miscarriage.
Somatic
Occurring in all cells, excluding the gonads.
Trimester
A division of pregnancy.
First: Weeks 1 - 13
Second: Weeks 14 - 26
Third: Weeks 27 -40
US
Ultrasound
Variable Expressivity
The same genetic condition can present with different clinical symptoms (phenotypes) in different individuals, even in individuals with identical mutations (genotypes)
