Title: What are Single Gene Disorders?
Headings: What are Single Gene Disorders?
What are Single Gene Disorders?
Types of single gene disorders
Examples of single gene disorders
References
Further Reading
Dr. Tomislav Meštrović

Content: Autosomal dominant single gene disorders occur in individuals who contain a single mutant copy of the disease-associated gene. The affected individuals are heterozygous for the gene, which means that inheritance of only one copy from either an affected mother or an affected father is sufficient to cause a disease; hence the presence of a single nonmutant or “wild-type” copy of the gene is not enough to prevent the disease. Another common mode of inheritance is autosomal recessive single gene disorder, where two copies of the mutated gene are needed in order to have the disorder. They inherit one allele from the mother and one from the father, the risk of transmission of the disorder is 25%, while half of the unaffected offspring will be carriers for the gene
X-linked dominant inheritance follows a pattern similar to autosomal dominant inheritance except that more females are affected than males, although such disorders are very rare. X-linked recessive conditions generally occur only in males, as second X-chromosome of females provides a normal allele, but males who inherit the recessive gene on their sole X-chromosome will be affected. Extremely rare Y-linked single gene diseases are always passed on from affected fathers to their sons. Inheritance of single gene disorders. Image Credit: Katrien Francois / Shutterstock.com
Examples of single gene disorders
Huntington's disease is a progressive neurodegenerative disorder that exhibits autosomal dominant inheritance.