Albinism – Types, Symptoms, Causes and Treatment

Definition of Albinism and Pigmentation Albinism is a genetic disorder in which the melanocytes do not produce, or produce reduced amounts of, melanin, the chemical that deposits pigment in cells of the SKIN, HAIR, and structures of the EYE. Without melanin, the skin, eyes, and hair have little or no pigment and consequently lack color. People who have albinism […]

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Mosaicism – what is and definition

Mosaicism Definition A chromosomal disorder in which some cells are normal and some cells contain the chromosomal abnormalities of the disorder, in contrast to a complete distribution of the abnormal chromosomes throughout all cells. The distribution of abnormal cells in mosaicism is usually random and unpredictable. Mosaicism most commonly occurs in AUTOSOMAL TRISOMY, in which there is […]

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Alopecia Areata – Definition, Causes and Symptoms

Definition of Alopecia Areata Alopecia Areata is a form of HAIR loss (ALOPECIA) that results from an autoimmune disorder in which the IMMUNE SYSTEM attacks clusters of hair follicles, halting hair growth. The clusters typically appear as circular patches of hairless SKIN, which are most noticeable when they occur on the scalp though can occur anywhere on the body. Hair growth […]

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Patau’s syndrome – Trisomy 13 – definition

Patau’s syndrome Definition Patau’s syndrome – an AUTOSOMAL TRISOMY disorder that results from a REPLICATION ERROR during cell division in which a GAMETE (sex cell) ends up with two copies of CHROMOSOME 13 instead of the normal single copy (as haploid cells, gametes contain one-half the complement of chromosomes). At CONCEPTION the ZYGOTE thus ends up with three instead of the normal two […]

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Ichthyosis – Diagnosis and Treatment

Definition of Ichthyosis Ichthyosis is a genetic disorder of keratinization in which the cells the SKIN sheds as part of its continual renewal cluster on the skin’s surface in scalelike formations. The lesions itch and flake, and the involved surfaces of the skin become very dry, reddened, and inflamed. Ichthyosis may affect limited areas of the skin or most […]

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Phenylketonuria (PKU) – symptoms and treatment

Phenylketonuria Definition An inherited genetic disorder in which the enzyme phenylalanine hydroxylase is missing or severely deficient, preventing the METABOLISM of the essential amino acid (one the body must acquire from dietary sources) phenylalanine. Phenylalanine is common in all foods that contain protein (such as meats, dairy products, fish, and legumes) and in artificial sweeteners […]

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Pemphigus – Vulgaris, Foliaceus, Pemphigus – Definition

Definition of Pemphigus Pemphigus is an autoimmune disorder in which large, painful bullae (blisters) form on the SKIN and mucous membranes. The bullae develop within the epidermis, the skin’s uppermost layer, giving them a very thin surface. They rupture and tear easily, exposing the skin to INFECTION and interfering with the skin’s ability to carry out its numerous functions. The ruptured […]

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Porphyria – symptoms and treatment

Porphyria Definition Porphyria – The collective term for a group of eight inherited GENETIC DISORDERS of METABOLISM in which deficiencies of certain enzymes block the production of heme and allow the accumulation of porphyrins. Heme is an iron-containing pigment normally present in nearly all tissues in the body, notably as a component of HEMOGLOBIN in the BLOOD and of electron […]

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Familial Adenomatous Polyposis (FAP)

Familial Adenomatous Polyposis Definition A genetic disorder in which hundreds of intestinal polyps grow in the RECTUM and COLON. FAP is an extreme risk for early-onset COLORECTAL CANCER. This autosomal dominant disorder results from a defective gene, inherited from one parent, in which there is a MUTATION of the adenomatous polyposis coli (APC) GENE. The ACP gene regulates the […]

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Progeria – disease

Progeria Definition and Diagnostic Path A very rare genetic disorder, commonly called severe premature aging, that arises from a MUTATION in a single GENE on CHROMOSOME 1 called lamin A (LMNA). The gene encodes a protein, also called lamin A, that is important for proper functioning of the membrane of the cell nucleus. In progeria this protein is abnormal, resulting in rapid […]

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