Article

Type I Hyperprolinemia: Genotype/Phenotype Correlations

Inserm U614, IHU, 76000 Rouen, France.
Human Mutation (Impact Factor: 5.05). 08/2010; 31(8):961-5. DOI: 10.1002/humu.21296
Source: PubMed

ABSTRACT Type I hyperprolinemia (HPI) is an autosomal recessive disorder associated with cognitive and psychiatric troubles, caused by alterations of the Proline Dehydrogenase gene (PRODH) at 22q11. HPI results from PRODH deletion and/or missense mutations reducing proline oxidase (POX) activity. The goals of this study were first to measure in controls the frequency of PRODH variations described in HPI patients, second to assess the functional effect of PRODH mutations on POX activity, and finally to establish genotype/enzymatic activity correlations in a new series of HPI patients. Eight of 14 variants occurred at polymorphic frequency in 114 controls. POX activity was determined for six novel mutations and two haplotypes. The c.1331G>A, p.G444D allele has a drastic effect, whereas the c.23C>T, p.P8L allele and the c.[56C>A; 172G>A], p.[Q19P; A58T] haplotype result in a moderate decrease in activity. Among the 19 HPI patients, 10 had a predicted residual activity <50%. Eight out of nine subjects with a predicted residual activity > or = 50% bore at least one c.824C>A, p.T275N allele, which has no detrimental effect on activity but whose frequency in controls is only 3%. Our results suggest that PRODH mutations lead to a decreased POX activity or affect other biological parameters causing hyperprolinemia.

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    ABSTRACT: There are two classifications of hereditary hyperprolinemia, type I (HPI) and type II (HPII). Eachtypeis caused by an autosomalrecessiveinborn error of the proline metabolic pathway. HPI is caused by an abnormality in the proline-oxidizing enzyme (POX). HPII is caused by a deficiency of Δ-1-pyrroline-5-carboxylate (P5C) dehydrogenase (P5CDh). The clinical features of HPI are unclear. Nephropathy, uncontrolled seizures, mental retardation or schizophrenia were reported in HPI, but a benign phenotype without neurological problems was also reported. The clinical features of HPII are also unclear. In addition, the precise incidences of HPI and HPII are unknown. Only 2 cases of HPI and one case of HPII were found in Japan through a questionnaire survey and by a study of previous reports. This suggests that hyperprolinemia is a very rare disease in Japan, consistent with earlier reports in Western countries. The one case of HPII found in Japan was diagnosed in an individual with influenza-associated encephalopathy. This finding suggested that HPII might reduce the threshold for convulsions, thereby increasing the sensitivity of individuals with influenza-associated encephalopathy. The current study presents diagnostic criteria for HPI and HPII, based on plasma proline levels, with or without measurements of urinary P5C. In the future, screening for HPI and HPII in healthy individuals, or patients with relatively common diseases such as developmental disabilities, epilepsy, schizophrenia or behavioral problems will be important.
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    ABSTRACT: The neuropsychiatric phenotype associated with hyperprolinemia type I (HPI) is still under debate. To our knowledge, no long-term follow-up on patients with HPI has been reported so far. We have previously described the clinical, biochemical, and molecular features of four patients with HPI. Here, we report on the neuropsychiatric and genotype features of an expanded sample of 10 patients with HPI with a mean follow-up duration of 11 years. Epileptic manifestations and/or cognitive impairment were prevalent at onset, but they were subsequently replaced by psychiatric disorders. Social behavior and relational skills were considerably impaired in the majority of cases. Learning disability was present in one patient. The complex neurochemical effects of proline on the central nervous system and genotype/phenotype correlations were discussed.
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    ABSTRACT: Although hyperprolinemia type-II has a discriminative metabolic phenotype and is frequently associated with neurological system involvement, the casual relation between the metabolic abnormalities and the clinical features, except for those of the secondary B6 deficiency, has been frequently debated. In order to evaluate disease frequency and the neuro-metabolic outcome we searched our laboratory database between 1992 and 2010, including 20,991 urinary organic acid profiles. From these individuals 16,720 parallel blood samples were available, and were investigated by serum amino acid analysis. We also evaluated the clinical, neurological, psychological features, laboratory data and vitamin levels and therapeutic effect in metabolically confirmed hyperprolinemia. Due to the mitochondrial localization of both ALDH4A1 and PRODH mitochondrial enzyme complex activity was evaluated and oxygen consumption was measured to assess ATP production in patient-fibroblasts. The Mitochondrial Disease Score was used to evaluate clinical mitochondrial dysfunction. The child behavior checklist was used to screen for psychopathology. We found four patients with increased urinary P5C diagnosed with hyperprolinemia type II, and only one patient had hyperprolinemia type I. All children with hyperprolinemia type II had low normal B6 concentration, and three of the patients had biochemical markers suggesting mitochondrial dysfunction. Mitochondrial dysfunction was confirmed in a muscle biopsy in one case. Intellectual disability was found in two adolescent patients. All patients showed seizures and significant behavioral problems, including anxiety and hallucinations. The clinical course was non-progressive and independent from the B6 concentration and B6 therapy. Hyperprolinemia is a rare inborn error. Individuals with hyperprolinemia should be monitored closely due to their frequent behavioral problems.
    Journal of Inherited Metabolic Disease 10/2013; DOI:10.1007/s10545-013-9660-9 · 4.14 Impact Factor

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