The skin, the largest organ in the body, protects the internal organs, prevents water loss, controls body temperature and provides sensory input. Skin contains three distinct layers. The outer layer, known as the epidermis, consists of three main types of cells: the keratinocytes, melanocytes that produce the pigment melanin and langerhans cells that function within the immune system. The dermis, the middle layer, contains connective tissues, including elastin and collagen, which give skin its elasticity and strength. The subcutaneous inner layer contains fat. Many types of rare genetic disorders affect the skin.
Causes
Disorders classified as genetic disorders occur as a result of a change, or mutation, in a gene. The human body consists of millions of genes---segments of DNA that code for a specific trait. Some genetic skin disorders, such as those classified as Ehlers-Danlos syndrome, occur when a parent passes a mutated gene on to a child, known as an inherited genetic disorder. Other rare genetic skin disorders, such as some forms of neurofibromatosis, occur when a gene randomly mutates in response to an environmental factor.
Collagen Disorders
Collagen, the most abundant protein in the human body, gives skin its strength and elasticity. Genetic disorders that affect genes responsible for collagen production can cause a lack of collagen or result in defective collage proteins. Ehlers-Danlos syndrome describes a group of rare, inherited, genetic disorders that cause stretchy, fragile skin due to a disruption in collagen production. The symptoms of Ehlers-Danlos syndrome include velvety feeling skin and skin that bruises or tears easily, which may limit physical activities.
Nuclear Factor Kappa B Disorders
Nuclear factor-kappa-B describes a group of proteins that protect the cells from self-destructing, as described by the Genetics Home Reference. A rare genetic defect in the gene coding for these proteins, a condition known as incontinentia pigmenti, causes skin cells to self destruct, resulting in blistering rashes and hair loss and wart-like skin growths. Other forms of incontinentia pigmenti cause these proteins to deposit excessive amounts of skin pigment known as melanin. This causes slate-grey, blue or brown skin pigmentation that appears marbled, as described by the National Institute of Neurologic Disorders and Stroke.
Tumor Disorders
Both inherited genetic mutations and spontaneous genetic mutations can cause genetic disorders that result in the formation of tumors on the skin. Tuberous sclerosis describes a rare genetic disorder that affects the genes that suppress tumor growth. Patients with TS develop noncancerous tumors on the skin, heart, kidneys and eyes. Neurofibromatosis, a genetic neurological disorder, causes tumors to grow along the body's nerves either on or just under the skin, according to the National Human Genome Research Institute.
Psychological Issues
In addition to any physical symptoms, rare genetic disorders of the skin can result in psychological issues. When skin appears abnormal, such as occurs with albinism---the absence of skin pigment---patients may experience self-esteem issues that prevent them from socializing with others. Ichythiosis, a family of rare genetic skin disorders, causes the skin to blister, appear scaly and shed. Disfiguring disorders such as these may result in psychological symptoms, including depression.
