Hydroxyprolinemia. 4-alpha-hydroxy-L-proline oxidase deficiency.
Incidence
Autosomal recessive. Less than 10 cases reported.
Clinical Characteristics
Hydroxyprolinemia was originally thought to result in mental retardation. Efron et al. (1965) described a clinical syndrome in which mental retardation and microscopic hematuria were present. Scriver and Efron (1972) described another case with mental retardation. However, the authors admitted that there may be no relation between the 2 findings, as the mother had mental retardation with normal hydroxyproline levels, and the child was believed to be born of related parents. Elevated serum hydroxyproline appears not to cause any significant clinical symptoms. Pelkonen and Kivirikko (1970) described hydroxyprolinemia in a brother and sister. No clinical abnormality was present and the authors suggested that hydroxyprolinemia, like cystathioninuria, is a 'non-disease.' Phang and Scriver (1989) stated that 'there is no evidence that the metabolic phenotype is a cause of clinical manifestation.' Bias of ascertainment is introduced by the fact that the hyperhydroxyprolinemia is found in patients investigated because of abnormality. They knew of reports of 6 probands.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
4-hydroxy-L-proline oxidase deficiency. Hydroxyprolinemia on quantitative aminoacid evaluation in plasma.