Furthermore, genetic testing may confirm the diagnosis in those with limited symptoms who otherwise would have been labeled "possible HHT" (see below).Genetic diagnosis in HHT is difficult, as mutations occur in numerous different locations in the linked genes, without particular mutations being highly frequent (as opposed to, for instance, the ΔF508 mutation in cystic fibrosis). Sequence analysis of the involved genes is therefore the most useful approach (sensitivity 75%), followed by additional testing to detect large deletions and duplications (additional 10%). Not all mutations in these genes have been linked with disease.Mutations in the MADH4 gene is usually associated with juvenile polyposis, and detection of such a mutation would indicate a need to screen the patient and affected relatives for polyps and tumors of the large intestine. Criteria
The diagnosis can be made depending on the presence of four criteria, known as the "Curaçao criteria". If three or four are met, a patient has "definite HHT", while two gives "possible HHT":

Spontaneous recurrent epistaxis
Multiple telangiectasias in typical locations (see above)
Proven visceral AVM (lung, liver, brain, spine)
First-degree family member with HHTDespite the designation "possible", someone with a visceral AVM and a family history but no nosebleeds or telangiectasias is still extremely likely to have HHT, because these AVMs are very uncommon in the general population. At the same time, the same cannot be said of nosebleeds and sparse telangiectasias, both of which occur in people without HHT, in the absence of AVMs.
Vocal cord hemorrhage occurs when a blood vessel in the vocal cords ruptures, which results in leakage of blood into the superficial lamina propria and dysphonia (hoarseness). The rupture usually results from overly forceful or incorrect vocalization, and may be a one-time occurrence or occur repeatedly. According to News Medical.net, "professional singers are at an increased risk of vocal hemorrhage, particularly in cases where gruelling performance schedules are followed". The treatment is  vocal rest as failure to rest the voice can result in permanent scarring. == References ==