Term
| What is the difference between a diagnostic test and a predictive test? |
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Definition
a diagnostic test is used to determine if the patient has or is free from a disease
a predictive test is used determine if the person has the disease, but has yet to show any physical problems the disease as in Huntington's Disease |
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Term
| What kind of conditions show up in a family history (pedigree) as a single isolated case? |
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Definition
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Term
| A consanguineous marriage roughly ________the risk for abnormal children? |
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Definition
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Term
| What are the different genetic disorders that can occur? |
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Definition
1) chromosomal abnormality
2) autosomal dominant condition, fully or partially penetrant
3) autosomal recessive condition
4) X-linked condition, dominant or recessive
5) condition caused by a defect in mitochondrial DNA
6) multifactorial condition
7) non-genetic cause |
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Term
| What are the four features of an autosomal dominant disorder? |
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Definition
1) vertical pedigree problem, with multiple generations affected
2) each affected person normally has one affected parent
3) each child of an affected person has a 1 in 2 chance of being affected
4) males and females are equally affected and likely to pass on the condition |
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Term
| What are the 5 features of an autosomal recessive disorder? |
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Definition
1) horizontal pedigree problem, with one or more sibs affected; usually only see a single affection
2) parents and children of affected people are normally unaffected
3) each subsequent sib of an affected child has a 1 in 4 chance of being affected
4) males and females are equally affected
5) affected children are sometimes the product of a consanguineous marriage. If family has several of these might see several generations affected |
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Term
| What are the 4 features of an X-linked recessive disorder? |
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Definition
1) a 'knights move' pedigree pattern, affected boys might have affected maternal uncle
2) parents and children of affected people are normally unaffected; never passed from father to son
3) affects mainly males: females can be carriers, and affected males in a pedigree are linked through females, not through unaffected males
4) subsequent brothers of affected males have a 1 in 2 chance of being affected; sisters are not affected, but have a 1 in 2 chance of being carriers |
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Term
| What are the 2 features of X-linked dominant disorders? |
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Definition
1) features very similar to autosomal dominant pedigrees; except that all daughters, but no sons of an affected father are affected
2) condition is often milder and more variable in females than males |
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Term
| What are 3 features of a Y-linked disorder? |
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Definition
1) a vertical pedigree pattern
2) all sons of an affected father are affected
3) affects only males |
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Term
| What are 3 features of a mitochondrial disorder? |
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Definition
1) a vertical pedigree problem
2) children of affected males are never affected
3) all children of an affected female may be affected, but mitochondrial conditions are typically extremely variable even within a family |
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Term
| In terms of penetrance, what are the two different ways to describe the passing on a trait when penetrance goes from (a) highly penetrant to (b) lowly penetrant? |
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Definition
a) Mendelian inheritance
b) Multifactorial inheritence |
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Term
| What type of disorder shows an unusual pattern of inheritance: heterozygous females are more severely affected than than hemizygous males? |
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Definition
| X-linked inheritance with cellular interference |
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Term
| What is it called when an autosomal condition may affect just one sex for anatomical or physiological reasons? |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| a person whose body contains two or more genetically different cell lines |
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Definition
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Term
| What are the 3 cases when mosaicism is clinically relevant? |
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Definition
1) if the mutant cells have a tendency to grow and take over
2) if the mutation arose sufficiently early in embryonic development so it makes up a big part of the body...person has features of the disease, but with milder phenotype
3) if the mutation affects the germ line (sperm or egg cells or their progenitors |
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Term
| conventional abbreviation for "allelomorph". Refers to the form of a gene at a locus. |
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Definition
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Term
| one of 22 pairs of chromosomes excluding the sex chromosomes (X & Y) |
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Definition
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Term
| the combination of proteins (such as histones) and nucleic acids that make up chromosomes. |
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Definition
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Term
| threadlike structure (literally "colored body") consisting of chromatin. Genes are arranged along this. |
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Definition
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Term
| 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 system. |
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Definition
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Term
| A 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
| Coefficient of relationship |
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Term
| the mating of related individuals |
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Definition
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Term
| Having two copies of each chromosome. In humans this number is 46. |
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Definition
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Term
| Allele that is expressed in the same way in a single copy (heterozygote) as in a double copy (homozygote). |
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Definition
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Term
| A trait in which the same genotype may produce phenotypes of varying severity or expression. An example is neurofibromatosis type 1. |
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Definition
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Term
| The haploid germ cell (egg or sperm) |
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Definition
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Term
| An individual's allelic constitution at a locus. |
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Definition
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Term
| Cells having one copy of each chromosome, the typical state for gametes. In humans, this number is 23. |
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Definition
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Term
| A gene present in only a single copy. Most commonly refers to genes on a 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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Definition
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Term
| Two or more distinct DNA sequences of the mitochondrial genome within the same cell. |
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Definition
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Term
| An individual who has two different alleles at the same locus. |
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Definition
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Term
| An individual whom the two alleles are the same at the same locus. |
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Definition
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Term
| The chromosome location of a specific gene |
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Definition
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Term
| A proposal that one X-chromosome is randomly inactivated in each each somatic cellof the normal female embryo. |
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Definition
| Lyon's Hypothesis...this process is called Lyonization and would create the barr body |
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Term
| Cell division process in which haploid gametes are formed from diploid germ cells. |
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Definition
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Term
| An alteration in a genomic DNA sequence that is heritable |
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Definition
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Term
| A diagram that describes family relationships, gender, disease status, and other attributes |
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Definition
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Term
| In a population, the proportion of individuals possessing a disease-causing genotype who displays the disease phenotype. When this proportion is less than 100%, the disease genotype is said to have reduced or incomplete ___________. |
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Definition
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Term
| The observed characteristics of an individual, produced by the interaction of genes and environment. |
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Definition
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Term
| 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
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Term
| a locus in which two or more alleles have gene frequencies greater than 0.01 in the population. |
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Definition
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Term
| A table specifying the genotypes that can arise from the gametes contributed by a mating of individuals |
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Definition
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Term
| An allele that is phenotypically expressed only in the homozygous or hemizygous state. This allele is masked by a dominant allele when the two occur together in a heterozygote. |
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Definition
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Term
| refers to changes in the proportions of mitochondrial DNA alleles as the mitochondria reproduce |
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Definition
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Term
| the occurrence of of a disease in a family with no apparent genetic transmission pattern, often the result of a new mutation |
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Definition
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Term
| a trait in which the same genotype may produce phenotypes of varying severity or expression |
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Definition
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Term
| process in which genes from one X-chromosome in each cell of the female embryo are rendered transcriptionally inactive |
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Definition
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Term
| Refers to genes that are located on the X-chromosome |
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Definition
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