Hyperhidrosis is a medical condition characterized by excessive sweating that goes beyond what the body needs to regulate its temperature. This means sweating can occur even at rest or in cool environments. While not life-threatening, this condition can significantly impact an individual’s daily life, affecting social interactions, work, and overall emotional well-being. Approximately 4.8% of the U.S. population experiences hyperhidrosis, affecting both men and women equally.
Understanding Dominant and Recessive Inheritance
Traits are characteristics passed from parents to offspring through genes, which are segments of DNA. Each person inherits half of their chromosomes from their father and half from their mother, resulting in a unique combination of genes. Genes often exist in different forms called alleles, and the interaction between these alleles determines how a trait is expressed.
In dominant inheritance, only one copy of a specific gene variant is needed for the trait to appear. For instance, a dominant allele for brown eyes will result in brown eyes, even if a blue-eye allele is also present. Recessive inheritance requires two copies of a specific gene variant—one from each parent—for the trait to be expressed. If only one recessive allele is present, the dominant allele will typically mask its effect. Blue eyes, a recessive trait, require two copies of the blue-eye allele to be expressed.
Genetic Patterns in Hyperhidrosis
Primary focal hyperhidrosis, which involves excessive sweating in specific areas like the hands, feet, underarms, or face, is an autosomal dominant inheritance pattern. This means that if one parent has the gene, there is a 50% chance their child will inherit it. Studies show that between 30% and 50% of individuals with hyperhidrosis have at least one family member also affected by the condition, suggesting a genetic link.
Despite this dominant inheritance pattern, not everyone who inherits the gene will develop noticeable symptoms, a concept known as variable penetrance. For example, research indicates that if one parent has primary hyperhidrosis, their child has about a 28% risk of developing the condition, even though the genetic inheritance chance is 50%. This suggests that other genetic factors or environmental influences may also play a role in whether the condition fully manifests. While the exact genes associated with hyperhidrosis have not been definitively isolated, evidence points to a dominant gene being a factor.
When Hyperhidrosis Is Not Inherited
Secondary hyperhidrosis, unlike the primary form, is caused by an underlying medical condition or can be a side effect of certain medications. This type of hyperhidrosis often presents as generalized sweating affecting the entire body, rather than specific areas, and typically begins in adulthood.
Various medical conditions can lead to secondary hyperhidrosis, including thyroid problems, diabetes, menopause, and certain types of cancer. A range of medications can also induce excessive sweating as a side effect, such as some pain relievers, antidepressants, and certain diabetes or hormonal medications. Identifying the root cause of secondary hyperhidrosis is important, as addressing the underlying condition or adjusting medication can often alleviate the sweating.