genetic terms

Here is a list of genetic terms you may have forgotten but may find useful in discussing certain diseases or conditions:

autosome a gene located on the 46 chromosomes that are not the sex chromosomes Blood type
gene that portion of the genetic code that specifies a certain trait (in actuality, a protein or an enzyme) Blood type
dominant gene a gene that is always expressed, that is directly detectable in the individual Blood types A and B
recessive gene a gene that is only expressed when two identical copies coding for the same trait are present, one from the mother, one from the father Blood type O or Rh-negative factor
sex-linked gene a gene that is located on one of the sex chromosomes Blood clotting factor VIII resides on the X chromosome (see also more detailed discussion)
expression whether a gene is detectable by examination of the individual Blood types A and B are always expressed - if either or both genes are present, they are detected by routine blood typing
chromosome the DNA containing structure in the cell where the genes are located chromosomes are numbered 1-23 plus the two sex chromosomes X and Y
sex chromosome the X and Y chromosomes that determine the sex of an individual XX female
XY male

genotype the actual genes present at a given site on the chromosome  
phenotype how the genotype is expressed Blood type A gene is always expressed as either type A (or AB if the B gene is also present
mutation a change in the genetic code for a given trait - a new genotype which did not exist in either parent 25% of cases of neurofibromatosis represent new mutations
genetic disease a disease caused by a defect in the genetic code for a given trait - a disease state caused by inheritance of a defective gene (genotype) examples of genetic diseases include sickle cell disease and Marfan syndrome
trisomy abnormal presence of an extra chromosome - three instead of two copies of the respective chromosome Trisomy 21 - Down syndrome

Night, Night! Dr. Hull's Common Sense Sleep Solutions© Copyright© Site Information/Disclaimer