There are only two types of chromosomes, autosomal, or sex chromosomes. There is one pair of sex chromosomes and 22 pairs of autosomes. A gene is the part of a chromosome that codes for a particular function. There can be thousands of genes on a chromosome.An autosomal gene is PKD1, which codes proteins for the kidney. A mutation in PKD1 can cause polycystic kidney disease, or related complications. gene is the part of a chromosome that codes for a particular function. There can be thousands of genes on a chromosome. An autosomal gene is PKD1, which codes proteins for the kidney. A mutation in PKD1 can cause polycystic kidney disease, or related complications.