Title: Hereditary Lymphedema - NORD (National Organization for Rare Disorders)
Headings: Rare Disease Database
Rare Disease Database
Hereditary Lymphedema
Synonyms of Hereditary Lymphedema
Subdivisions of Hereditary Lymphedema
General Discussion
Signs & Symptoms
Causes
Affected Populations
Diagnosis
Standard Therapies
Treatment
Investigational Therapies
Supporting Organizations
References
Years Published
Report Index

Content: Causes
Many researchers believe that hereditary lymphedema may result from changes (mutations) in one of the different disease genes (genetic heterogeneity). Most cases of hereditary lymphedema type IA and type II are inherited as autosomal dominant traits. Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child. Investigators have determined that some cases of hereditary lymphedema type IA (Milroy’s disease) occur because of mutation in the FLT4 gene which encodes of the vascular endothelial growth factor receptor 3 (VEGFR-3) gene located on the long arm (q) on chromosome 5 (5q35.3). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes.