Term
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Definition
| conventional abbreviation for "allelomorph". Refers to the form of a gene at a locus |
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Term
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Definition
| one of the 22 pairs of chromosomes excluding the sex chromosomes |
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Definition
| combination of proteins and nucleic acids that make up chromosomes |
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Definition
| threadlike structure consisting of chromatin. genes are arranged along chromosomes |
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Definition
| alleles that are both expressed when they occur together in the heterozygous state. Examples are the A and B alleles of the ABO blood group systen |
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| coefficient of relationship |
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Definition
| statistic that measures the proportion of genes shared by two individuals as a result of descent from a common ancestor |
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Definition
| mating of related individuals |
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Definition
| mating of related individuals |
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Definition
| having 2 copies of each chromosome. in humans the diploid number is 46 |
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Definition
| allele that is expressed in the same way in single copy (heterozygote) as in double copy (homozygote) |
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Definition
| trait in which the same genotype may produce phenotypes of varying severity or expression. An example is neurofibromatosis type 1 |
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Term
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Definition
| haploid germ cell (sperm or egg) |
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Term
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Definition
| individual's allelic constitution at a locus |
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Definition
| cells having one copy of each chromosome, the typical state for gametes. in humans the haploid number is 23 |
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Term
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Definition
| a gene present in only a single copy. Most commonly refers to genes on the single X chromosome in males, but can refer to other genes in the haploid state, such as the genes homologous to a deleted region of a chromosome |
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Term
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Definition
| two or more distinct DNA sequences of the mitochondrial genome within the same cell |
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Term
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Definition
| individual who has two different alleles at a locus. compare with homozygote |
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Term
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Definition
| individual in whom the two alleles at a locus. |
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Term
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Definition
| chromosome location of a specific gene |
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Term
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Definition
| a proposal (now verified) that one X-chromosome is randomly inactivated in each somatic cell of the normal female embryo (Lyonization) |
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Definition
| Cell division process in which haploid gametes are formed from diploid germ cells |
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Definition
| alteration in a genomic DNA sequence that is heritable |
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Definition
| diagram that describes family relationships, gender, disease status, and other attributes |
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Term
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Definition
| in a population, the proportion of individuals possessing a disease-causing genotype who display the disease phenotype. When this proportion is less than 100%, the disease genotype is said to have reduced or incomplete penetrance |
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Term
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Definition
| the observed characteristics of an individual, produced by the interaction of genes and environment |
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Term
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Definition
| the first person in a pedigree to be identified clinically as having the disease in question. Synonymous with propositus and index case. |
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Definition
| a locus in which two or more alleles have gene frequencies at greater than 0.01 in the population |
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Definition
| an allele that is phenotypically expressed only in the homozygous or hemizygous state. The recessive allele is masked by a dominant allele when the two occur together in a heterozygote |
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Definition
| refers to changes in the proportions of mitochondrial DNA alleles as the mitochondria reproduce |
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Definition
| the occurrence of a disease in a family with no apparent genetic transmission pattern, often the result of a new mutation |
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Term
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Definition
| a trait in which the same genotype may produce phenotypes of varying severity or expression |
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Term
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Definition
| process in which genes from one X-chromosome in each cell of the female embryo are rendered transcriptionally inactive |
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Term
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Definition
| refers to genes that are located on the X-chromosome |
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Term
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Definition
In the formation of gametes, the
paired hereditary determinants separate such that each gamete is equally
likely to contain either one. |
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Term
| Difference between Mendelian and Multifactorial inheritance |
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Definition
Multifactorial – multiple genes involved. Environment plays a bigger role in multifactorial diseases than in Mendelian diseases.
In Mendelian diseases, if you have the mutation then you have the disease. |
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Term
| Why are some DNA diagnostic tests unhelpful? |
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Definition
| DNA diagnostic test is helpful in a fully penetrant disease, but not in a reduced penetrant disease. |
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Term
| Examples of autosomal dominant disorders |
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Definition
Achondroplasia (dwarfism)
Neurofibromatosis type I (NF1)
Huntington disease
Hypercholesterolemia, type II
Marfan’s syndrome |
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Term
| Examples of autosomal recessive diseases |
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Definition
Cystic Fibrosis
Sickle cell disease
Gaucher Disease
Albinism
Phenylketourea (PKU) |
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| Examples of X-linked recessive diseases |
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Definition
Hemophilia A
Duchenne’s muscular dystrophy
Ornithine transcarbamoylase deficiency |
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Term
| Examples of X-linked dominant disorders |
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Definition
Hypophosphatemic ricketts
Incontinentia pigmenti Type 1 |
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Term
| Key inheritance pattern of mitochondrial disorders |
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Definition
| solely female to progeny (both genders) transmission |
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Term
| Examples of mitochondrial disorders |
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Definition
Leber optic neuropathy
Myoclonic epilepsy with ragged red fiber disease (MERFF)
Mitochondrial encephalopathy and stroke like episodes (MELAS) |
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Term
| Complicating factors of Mendelian inheritance |
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Definition
| New mutations, penetrance, expressivity, phenocopy (two different genes cause the same phenotype) |
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