Counselor Preparation Comprehensive Practice Examination

Which category of genetic disorder includes conditions like Down Syndrome?

1. X-linked Diseases

2. Autosomal Diseases

3. Sex Chromosomal Disorders

4. Mitochondrial Disorders

The correct answer is: Autosomal Diseases

Down Syndrome is classified as an autosomal disorder because it results from an abnormal number of chromosomes, specifically an extra copy of chromosome 21, leading to the condition known as trisomy 21. This places it within the category of autosomal diseases, which are genetic disorders that are linked to the chromosomes not involved in determining sex (the autosomes). Autosomal disorders can manifest in various ways, often leading to developmental and physical abnormalities, as seen in Down Syndrome. It is important to differentiate these from other categories such as X-linked diseases, which are caused by mutations on the X chromosome; sex chromosomal disorders, which involve abnormalities of the sex chromosomes; and mitochondrial disorders, which arise from mutations in mitochondrial DNA. Each of these categories involves distinct mechanisms of inheritance and characteristics that differentiate them from autosomal disorders like Down Syndrome.