Diagnosis
FSHD can be presumptively diagnosed in many cases based on signs, symptoms, and/or non-genetic medical tests. Genetic testing can provide definitive diagnosis. In the absence of an established family history of FSHD, diagnosis can be difficult due to the variability in how FSHD manifests. Genetic testing
Genetic testing is the gold standard for FSHD diagnosis, as it is the most sensitive and specific test available. Commonly, FSHD1 is tested for first. A shortened D4Z4 array length (EcoRI length of 10 kb to 38 kb) with an adjacent 4qA allele supports FSHD1. If FSHD1 is not present, commonly FSHD2 is tested for next by assessing methylation at 4q35. Low methylation (less than 20%) in the context of a 4qA allele is sufficient for diagnosis. The specific mutation, usually one of various SMCHD1 mutations, can be identified with next-generation sequencing (NGS). Assessing D4Z4 length
Measuring D4Z4 length is technically challenging due to the D4Z4 repeat array consisting of long, repetitive elements. For example, NGS is not useful for assessing D4Z4 length, because it breaks DNA into fragments before reading them, and it is unclear from which D4Z4 repeat each sequenced fragment came. In 2020, optical mapping became available for measuring D4Z4 array length, which is more precise and less labor-intensive than southern blot.Molecular combing is also available for assessing D4Z4 array length. These methods, which physical measure the size of the D4Z4 repeat array, require specially prepared high quality and high molecular weight genomic DNA (gDNA) from serum, increasing cost and reducing accessibility to testing.
Drug trials have found it to be as efficient as anti-VEGF drugs in eyes with artificial lenses over a two-year period. A systematic review did not find any evidence of any benefit in preventing vision loss in eyes treated with triamcinolone acetonide over placebo, for patients with age-related macular degeneration.Triamcinolone acetonide is also administered via intralesional injection in the treatment of hypertrophic and keloid scars.Uncommonly, intramuscular injection of triamcinolone acetonide may be indicated for the control of severe or incapacitating allergic states for which conventional treatments have failed, such as asthma, atopic dermatitis, contact dermatitis, perennial or seasonal allergic rhinitis, serum sickness, and transfusion and drug hypersensitivity reactions. Contraindications
Evidence suggests that usage of triamcinolone acetonide or other steroids to treat macular edema increases the risk of increasing intraocular pressure in patients.Triamcinolone acetonide should not be used by those with tuberculosis or untreated fungal, bacterial, systemic viral or herpes simplex infections without consulting a doctor first. Pharmacology
Pharmacodynamics
Triamcinolone acetonide is a corticosteroid. It is specifically a glucocorticoid, or an agonist of the glucocorticoid receptor, that is about five times as potent as cortisol. It has very little mineralocorticoid effects. The affinities of triamcinolone acetonide for the androgen and estrogen receptors are both <0.1% (relative to testosterone and estradiol). However, triamcinolone acetonide has 15% of the affinity of progesterone for the progesterone receptor. In relation to this, triamcinolone acetonide can produce endocrine side effects like ovulation inhibition and menstrual irregularities.