Genetics Definitions

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Across
  1. 6. A genetic alteration that is present for the first time in one family member as a result of a mutation in a germ cell of one of the parents, or a variant that arises in the fertilized egg itself during early embryogenesis.
  2. 11. More than one genotype can cause the same of a very similar phenotype.
  3. 12. Small populations that mate internally.
  4. 13. The variable phenotypic expression of a given genotype, which implies that a genetic disorder can manifest with different signs, symptoms, and degrees of severity in different individuals. Example: Marfan syndrome (some have mild symptoms (tall thin with slender fingers); others have life-threatening complications (aortic dissection)).
  5. 14. A mechanism of gene regulation in which one allele of a gene is silenced, while the other allele is expressed, depending on the parent from whom it was inherited. Example: Prader-Willi and Angelman.
  6. 15. A chromosomal abnormality in which offspring receive two copies of one chromosome from one parent and no copies from the other parent. This abnormality cannot be detected via karyotyping because the number of chromosomes is normal and there is no loss of genetic material.
Down
  1. 1. Phenotypic expression of a particular gene or genomic region is not observed in all individuals (i.e. some people with a disease-causing mutation develop disease, while others do not).
  2. 2. Group of neurological disorders caused by the expansion of a trinucleotide sequence (and thus faulty protein synthesis or folding).
  3. 3. A phenomenon in which different mutations of the same allele result in the same phenotype (e.g. different mutations at a single location cause the same disease).
  4. 4. Relating to or arising from non-genetic influences on gene expression. Affects the traits of offspring without altering the primary structure of DNA (i.e. the sequence of nucleotides. Examples: DNA methylation and histone acetylation.
  5. 5. A phenomenon in which gene mutations at different loci produce the same phenotype (e.g. mutations at different locations cause the same disease).
  6. 7. A phenomenon in which disease onset occurs earlier and/or the disease manifestation is more severe in offspring than in parents. Example: Trinucleotide repeat diseases (e.g. Huntington disease, myotonic dystrophy).
  7. 8. A gene change in a body's reproductive cell that becomes incorporated into the DNA of every cell in the body of the offspring.
  8. 9. A phenomenon in which one gene influences the development of multiple phenotypic traits.
  9. 10. Subset of allelic heterogeneity in which two different clinical disease phenotypes appear to be caused by mutations on different genes, but are really caused by different mutations at the same locus.