Gene abnormalities
Until recently, nodular fasciitis was considered a reaction to trauma or some other unidentified insult at the site where the tumor subsequently developed. However, recent findings indicate that up to 92% of NF tumors involve the self-limiting growth of a clone (i.e. a group of identical cells that share a common ancestry} of neoplastic cells that contain a fusion gene. Fusion genes are abnormal genes consisting of parts from two different genes that form as a result of large scale gene mutations such as chromosomal translocations, interstitial deletions, or inversions. The fusion gene found in NF tumor cells consists of a part of the USP6 gene combined with any one of numerous other genes. Its most common partner gene in NF is the MYH9 (i.e. myosin-9) gene. This USP6-MYH9 fusion gene forms as a result of a translocation of part of the USP6 gene located at band 13.2 on the long (or "q") arm of chromosome 17 with part of the MYH9 gene at band 13.2 on the short (or "p") arm of chromosome 22. Other genes that partner with the USP6 gene to form a fusion gene found in NF include the: RRBP1 (i.e.
Ornithine aminotransferase deficiency (also known as gyrate atrophy of the choroid and retina) is an inborn error of ornithine metabolism, caused by decreased activity of the enzyme ornithine aminotransferase. Biochemically, it can be detected by elevated levels of ornithine in the blood. Clinically, it presents initially with poor night vision, which slowly progresses to total blindness. It is believed to be inherited in an autosomal recessive manner. Approximately 200 known cases have been reported in the literature. The incidence is highest in Finland, estimated at 1:50,000.Research suggests there can be some adverse effect on muscles and also the brain. The cause of this is somewhat unclear but may relate to very low levels of creatine often found in this population. Treatment may include vitamin B6, lysine or dramatic dietary change to minimise arginine from patients diet. Research has indicated that these treatments may be somewhat effective in lowering ornithine blood concentration levels in some patients, either in combination or individually. Vitamin B6 has been found to be very effective in a small proportion of patients. Presentation
Quite often, the presenting symptom of ornithine aminotransferase (OAT) deficiency is myopia which progresses to night blindness. The onset of myopia is often in early childhood. Ophthalmological findings in affected individuals include constricted visual fields, posterior subcapsular cataracts (can begin in late teens), elevated dark adaptation thresholds and decreased or absent electroretinographic responses.