Focal hyperhidrosis, also known as primary hyperhidrosis, is a disease characterized by an excessive sweating localized in certain body regions (particularly palms, feet and underarms). Studies suggest that this condition, affecting between 1% and 3% of the US population, seems to have a genetic predisposition in about two thirds of those affected. Focal hyperhidrosis is sometimes referred to as The Silent Handicap, as it has a significant impact on the quality of life, affecting the individual socially, psychologically, emotionally and professionally. Genetics In 2006, researchers uncovered that primary palmar hyperhidrosis, referring to excess sweating on the palms of the hands and feet, maps to the gene locus 14q11.2-q13. After this discovery, further research was conducted to examine if primary focal hyperhidrosis maps back to the same locus. In addition, researchers wanted to see if other previously unknown genes were responsible for different phenotypes among individuals with hyperhidrosis. Based on previous research using mice and rats, researchers looked towards the role of aquaporin 5 (AQP5), a water channel protein, in human individuals with primary focal hyperhidrosis. AQP5 has been identified as a candidate gene in many hyperhidrosis studies. Using a family that had members with primary focal hyperhidrosis, researchers found that there was no connection between primary focal hyperhidrosis and AQP5. There was also no significant connection between the gene 14q11.2-q13 locus, which was linked to primary palmar hyperhidrosis, and primary focal hyperhidrosis in this family. Due to the inconclusive findings in the study, the question as to what are the genes and proteins that play a significant role in primary focal hyperhidrosis still remains. The expression of the AQP5 protein and AQP5 mRNA was significantly higher in a patient group in comparison to the control group. In 2011, using a control group (individuals without primary focal hyperhidrosis) and a patient group (individuals with primary focal hyperhidrosis) researchers found that there was no difference between the number of sweat coils in the axillary sweat glands. This indicates that there is nothing morphologically different between individuals with and without primary focal hyperhidrosis. The discrepancies between the studies above call on further studies to confirm or deny the role of AQP5, and the role of other proteins, in hyperhidrosis. Beyond looking at the genes and individual proteins that play a role in primary focal hyperhidrosis, researchers have looked at the patterns of heredity for this trait. In a 2003 study, using multiple families,