30.5: Key Terms

allele

alternative form of a gene that occupies a specific locus on a specific gene

autosomal chromosome

in humans, the twenty-two pairs of chromosomes that are not the sex chromosomes (XX or XY)

autosomal dominant

pattern of dominant inheritance that corresponds to a gene on one of the twenty-two autosomal chromosomes

autosomal recessive

pattern of recessive inheritance that corresponds to a gene on one of the twenty-two autosomal chromosomes

carrier

heterozygous individual who does not display symptoms of a recessive genetic disorder but can transmit the disorder to their offspring

chromosomal condition

condition related to changes in chromosome structure or number

chromosome

structure made of protein and a single molecule of DNA that carries genetic information in the form of genes

codominance

equal, distinct, and simultaneous expression of both parents’ different alleles

diagnostic genetic testing

testing performed to confirm or rule out a specific genetic disorder using a DNA-based test

dominant lethal inheritance

inheritance pattern in which individuals with one or two copies of a lethal allele do not survive in utero or have a shortened life span

empiric risk

chance for the occurrence of a disease based on personal and family history and other data

ethical, legal, and social implications (ELSI)

concerns related to advances in genetic and genomic knowledge that include informed decision-making, informed consent for genetic testing, consent related to genetic/genomic research, privacy and confidentiality, and discrimination prevention

frameshift mutation

mutation caused by insertions or deletions of a number of nucleotides that are not a multiple of three

gene

basic functional unit of heredity found in the nucleus of every cell; composed of deoxyribonucleic acid (DNA) sequences located in an individual’s chromosomes

genetic condition

condition caused by a single gene mutation

Genetic Information Nondiscrimination Act (GINA)

U.S. law that prohibits discrimination based on genetic information

genetic screening

process that evaluates a person’s risk of developing a genetic condition

genetic testing

testing that identifies mutations in a person’s DNA

genetics

study of heredity focused on patterns of inheritance of specific characteristics or traits, including variations of a trait within a population

genome-wide association studies (GWAS)

expanded area of research to identify common genetic factors that influence health and disease

genomic condition

disorder caused by the loss or gain of DNA material

genomics

study of genes and how they interact with each other and the environment

genotype

complete genetic makeup of an individual

germline mutation

mutation that originates in the parent’s reproductive cells (eggs or sperm) and is generally passed into every cell of the offspring’s body

heterozygous

having two different alleles for a given gene

homozygous

having two identical alleles for a given gene

induced mutation

genetic mutation from an extraneous exposure

karyotype

systematic arrangement of chromosome pairs

mitochondrial inheritance

pattern of inheritance transmitted only by mothers

mutation

change in the DNA sequence of an organism’s genetic material

pharmacogenetics

study of the variability of therapeutic responses to medications, as influenced by variations in single genes

pharmacogenomics

study of variations in multiple genes as associated with variable drug responses

phenotype

physical or biochemical manifestation of the genotype; expression of the alleles

point mutation

mutation in which a single nucleotide in a DNA sequence is substituted by another nucleotide

population screening

large-scale screening programs offering the general population testing for genomic disorders that may be prevented or effectively mitigated with early detection

recessive lethal inheritance

pattern of inheritance in which individuals with two copies of a lethal allele do not survive in utero or have a shortened life span

risk probability

likelihood that an individual carries a genetic mutation, predisposing the person for developing disease

sex chromosomes

pair of chromosomes involved in sex determination; in males, the XY chromosomes, and in females, the XX chromosomes

somatic mutation

mutation that arises in cells at some point after fertilization and does not involve the germline

spontaneous mutation

genetic mutation that occurs due to processes within the body

X-linked dominant

pattern of dominant inheritance that corresponds to a gene on the X chromosome of the twenty-third pair

X-linked recessive

pattern of recessive inheritance that corresponds to a gene on the X chromosome of the twenty-third pair

X-linked transmission

pattern of inheritance that involves genes located on the X chromosome of the twenty-third pair

Y-linked inheritance

pattern of inheritance that comes from one of the Y chromosomes of the father