Tyrosinemia type II

Tyrosinemia type II, also known as oculocutaneous tyrosinemia or Richner-Hanhart syndrome is an inborn error of the tyrosine catabolic pathway characterized by hypertyrosinaemia, keratitis, palmoplantar keratosis and variable intellectual disability. The skin is affected in approximately 80% of reported cases, the eye in approximately 75% and mental retardation is present in over 60% of reported cases. Symptoms may be confined exclusively to the skin or to the eyes. Skin findings usually begin after one year of life, but may manifest in individuals as young as one month and consist of painful, progressive, non-pruritic and hyperkeratotic plaques on the soles and palms often associated with hyperhidrosis. Eye manifestations usually occur before the skin lesions develop and include photophobia, redness and pain. Neurodevelopmental disability is variable, ranging from severe retardation to a mild decrease in intelligence; there appears to be no relationship between age of diagnosis and degree of intellectual disability.1 Lowering plasma tyrosine levels by restricting protein intake leads to resolution of eye and skin symptoms.hyperkeratotic plaques on the soles and palms often associated with hyperhidrosis. Eye manifestations usually occur before the skin lesions develop and include photophobia, redness and pain. Neurodevelopmental disability is variable, ranging from severe retardation to a mild decrease in intelligence; there appears to be no relationship between age of diagnosis and degree of intellectual disability. Lowering plasma tyrosine levels by restricting protein intake leads to resolution of eye and skin symptoms.

Tests Available

Forms and Documents

Test Details

TAT
  • Confirmation of biochemical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancies
  • Capillary Sequencing

Ordering

494
4-5 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL)|Buccal Swabs

Billing

81479x1
No
Yes
  • 796.6 Abnormal findings on neonatal screening
  • 270.2 Other disturbances of aromatic amino-acid metabolism, Albinism, Alkaptonuria, Alkaptonuric ochronosis, Disturbances of metabolism of tyrosine and tryptophan, Homogentisic acid defects, Hydroxykynureninuria Hypertyrosinemia, Indicanuria, Kynureninase defects, Oasthouse urine disease, Ochronosis, Tyrosinosis, Tyrosinuria, Waardenburg syndrome
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References

  1. Natt et al., (1987) Hum Genet 77:352-358.
  2. Natt et al., (1992) Proc Natl Acad Sci 89:9297-9301.
  3. Huhn et al., (1998) Hum Genet 102:305-313.
  4. Maydan et al., (2006) J Inherit Metab Dis 29:620-626.
  5. Charfeddine et al., (2006) Mol Genet Metab 88:184-191.