Richner-Hanhart Syndrome

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Richner-Hanhart Syndrome

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Synonym

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Tyrosinemia type II

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Inheritance

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Autosomal recessive; tyrosine aminotransferase gene on 16q22.1 q22

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Prenatal

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Amniocentesis: tyrosine aminotransferase assay
DNA analysis available if defect known in family

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Incidence

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Less than 50 cases reported; increased in patients with Italian ancestry; M=F

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Age at Presentation

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First few months of life (eye findings precede skin findings)

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Pathogenesis

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Mutations in the tyrosine aminotransferase gene on I 6q leads to deficiency of the hepatic enzyme with accumulation of tyrosine in all tissues; tyrosine crystals in corneal epithelium are thought to induce an inflammatory response; tyrosine may stimulate microtubule assembly

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Clinical

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Skin
Focal (weight bearing plantar surfaces, hypothenar or thenar emminences, finger-tips) or diffuse palmoplantar keratoderma; with/without pain with impaired ambulation, erosions, bullae, erythema; Hyperkeratotic plaques on elbows, knees

Eyes
Severe keratitis with photophobia, corneal ulceration, neovascularization, and
Blindness

Central Nervous System

With/without mental retardation

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D/Dx

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Other forms of PPK
Herpetic keratitis

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Lab

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Increased plasma tyrosine levels
Increased urinary tyrosine metabolites

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Management

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Referral to nutrition ist low phenylalanine/low tyrosine diet
Referral to dermatologist topical therapy, oral retinoids
Referral to ophthalmologist

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Prognosis

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If dietetic intervention made early enough, can prevent cutaneous and ocular complications; mental retardation may not respond to diet