The “-uria” Genodermatoses:

*

Deficient Enzyme

Dermatologic feature

Urine

Comments

Argininosuccinic Aciduria

AR

arginosuccinase

trichorrhexis nodosa

mentally retarded if survive beyond the neonatal period

Phenylketonuria

AR

phenylalanine hydroxylase

albino-like (blond hair, blue eyes, generalized hypopigmentation)**

“mousy” odor

don’t see it anymore, screened at birth

Homocystinuria

AR

cystathionine beta-synthase

marfanoid habitus;  (downward ectopia lentis vs. upward in Marfan’s)

Alkaptonuria

AR

homogentisic acid oxidase

dark urine when pH > 7.0 (i.e. diapers, clothing discolors after cleaning with alkaline soap)

AKA ochronosis

*AR = autosomal recessive   (all of the “-uria” genodermatoses are autosomal recessive)

** phenylalanine accumulates and competitively inhibits tyrosine in melanogenesis and has toxic affects on the CNS