As absorption and reabsorption of glycine, proline and hydroxyproline occurs through PAT1 as well, it is believed to play another role in expressing the malabsorptive iminoglycinuria phenotype. Recent reports, however, suggest a more diminished role from PAT1 in some cases of the disorder.While PAT2 is strongly indicated as the primary mutagen responsible for iminoglycinuria, the variability of the phenotype is found to be instituted by three modifying genetic mutations. The major one among these is believed to be system IMINO.Defined as the sodium-dependent proline transporter not inhibited by alanine, system IMINO, believed to be formed by the SLC6A20 (SIT1) gene, is a crucial mammalian transport mechanism responsible for both renal reabsorption and intestinal absorption of proline and other imino acids, such as hydroxyproline and pipecolate. The mRNA sequence for SIT1 is expressed in a great deal of the gastrointestinal tract, including the stomach, duodenum, jejunum, ileum, cecum and colon. It is also found in the kidney, optical choroid, and parts of the central nervous system such the brain and microglial cells.Reduced penetrance is a phenomenon where a fully inherited genetic trait, such as a disease or disorder, fails to exhibit the expected phenotype. This has been reported in some cases of iminoglycinuria. Here, system IMINO is thought to play a role in reduced penetrance of iminoglycinuria by compensating for imino acid malabsorption related specifically to mutations of PAT2.
Telangiectasias, also known as spider veins, are small dilated blood vessels that can occur near the surface of the skin or mucous membranes, measuring between 0.5 and 1 millimeter in diameter. These dilated blood vessels can develop anywhere on the body, but are commonly seen on the face around the nose, cheeks and chin. Dilated blood vessels can also develop on the legs, although when they occur on the legs, they often have underlying venous reflux or "hidden varicose veins" (see Venous hypertension section below). When found on the legs, they are found specifically on the upper thigh, below the knee joint and around the ankles. Many patients with spider veins seek the assistance of physicians who specialize in vein care or peripheral vascular disease. These physicians are called vascular surgeons or phlebologists. More recently, interventional radiologists have started treating venous problems. Some telangiectasias are due to developmental abnormalities that can closely mimic the behaviour of benign vascular neoplasms. They may be composed of abnormal aggregations of arterioles, capillaries or venules. Because telangiectasias are vascular lesions, they blanch when tested with diascopy. Telangiectasias, aside from presenting in many other conditions, are one of the features of the acronymically named CREST syndrome, a form of systemic scleroderma. The syndrome recognises the significantly co-presenting symptoms of calcinosis, Raynauds phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia. Causes
The causes of telangiectasia can be divided into congenital and acquired factors. Genetic
Goldman states that "numerous inherited or congenital conditions display cutaneous telangiectasia".