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Introduction Hair loss is a disorder in which the hair falls out from skin areas where they are usually present, such as the scalp and the body. This loss interferes with the  many  useful  biologic  functions  of  the  hair,  including  sun  protection  (mainly  to  the  scalp)  and  dispersal of sweat …

Introduction HIV is a virus that attacks the immune system, which is our body’s natural defense against illness. The virus destroys a type of white blood cell in the immune system called a T-helper cell, and makes copies of itself inside these cells. T-helper cells are also referred to as …

Definition Hunters syndrome is a very rare, inherited genetic disorder caused by a missing or malfunctioning enzyme. In Hunter syndrome, the body doesn’t have enough of the enzyme iduronate 2-sulfatase. This enzyme’s job is to break down certain complex molecules, and without enough of this enzyme, the molecules build up …

Definition Hemophilia is an inherited bleeding disorder in which a person lacks or has low levels of certain proteins called “clotting factors” and the blood doesn’t clot properly as a result. This leads to excessive bleeding. Bleeding disorders are due to defects in the blood vessels, the coagulation mechanism, or …

Definition Hemochromatosis is an iron disorder in which the body simply loads too much iron. This action is genetic and the excess iron, if left untreated, can damage joints, organs, and eventually be fatal.   Types of hemochromatosis Hereditary hemochromatosis isn’t the only type of hemochromatosis. Other types include: Juvenile …

Definition Huntington’s disease (HD) is a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain. It deteriorates a person’s physical and mental abilities during their prime working years and has no cure. HD is known as the quintessential family disease because every child of a …

Hyperpigmentation – Definition Hyperpigmentation refers to areas of skin where an excess of melanin has been produced and formed deposits, causing skin patches that appear darker than the surrounding skin. Common skin areas that experience hyperpigmentation or dyschromia are the face, arms, and hands.  Age spots, liver spots, freckles, sun …