Iowa Institute of Human Genetics

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  • A

    A:

    See adenine

    AA:

    See amino acid

    AD:

    See autosomal dominant

    Allele:

    An alternate form of a gene at a given locus or location in the genome. Each locus has two alleles, one inherited from each parent.

    Affected:

    An individual diagnosed with a disease or disorder of who shows signs or symptoms of a condition.

    Allelic heterogeneity:

    Variant alleles found at a single locus which can result in the same phenotype.

    Amino Acid:

    One of 20 molecules made by instructions contained in DNA. These molecules are linked together to form proteins.

    Anticipation:

    An earlier age of onset and/or greater severity of disease with subsequent generations in a family seen with certain genetic disorders, notably the trinucleotide repeat disorders.

    AR:

    See autosomal recessive

    Association:

    A statistical relationship between two variables. Most commonly an allele found more or less frequently with a specific disease than in the general population.

    Autonomy:

    The right to make decisions about oneself.

    Autosome:

    A chromosome that is not a sex chromosome. Humans have 22 pairs of autosomes.

    Autosomal:

    Inheritance of a gene on an autosome. A disease caused by a gene not on a sex chromosome has autosomal inheritance.

    Autosomal Dominant:

    A disease caused by a gene not on a sex chromosome. The phenotype/disease/trait is expressed by individuals who have one copy of the gene variant. Individuals with an autosomal dominant condition have a 50% chance of passing the gene variant to offspring with each pregnancy.

    Autosomal Recessive:

    A disease caused by a gene not on a sex chromosome. The phenotype/disease/trait is expressed by individuals who have inherited two genetic variants at the same locus or gene. Most often one changed copy of the gene is inherited from each parent.