It is important to clarify at the outset the difference between chromosome abnormalities and single gene disorders. Chromosome abnormalities are errors that result in an abnormal chromosome number or an abnormal chromosome structure. These abnormalities lead to the loss or gain of chromosome material. All the genes within these chromosomes, however, are normal.
Most chromosome abnormalities are sporadic with a small to negligible risk of recurrence.
In the case of single gene disorders, the error lies in a mutation or change within the DNA sequence. Errors that occur within a gene can result in absent, deficient or abnormal protein products. Therefore, chromosome studies are not recommended for patients who are thought to have a single gene disorder such as cystic fibrosis or muscular dystrophy. All rights reserved.