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Clinical, biochemical and enzymatic studies in type I hyperprolinemia associated with chromosomal abnormality
Insights
This study reports a case of severe mental retardation in an infant with type I hyperprolinemia and a chromosomal abnormality. Dietary proline restriction improved blood levels but not cognitive development, suggesting age-dependent treatment adjustments.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Type I hyperprolinemia is an inherited metabolic disorder.
- Associated chromosomal abnormalities can exacerbate clinical presentation.
- This case highlights the complexity of hyperprolinemia in infants.
Observation:
- A patient presented with severe mental and motor retardation, convulsions, and characteristic facial features.
- Karyotype analysis revealed partial duplication of the short arm of chromosome 10.
- Both the patient and her mother exhibited fasting hyperprolinemia and abnormal proline load responses.
Findings:
- Liver proline oxidase activity was significantly reduced (9% of controls).
- Enzyme kinetics were normal, suggesting a quantitative rather than qualitative defect.
- Dietary proline restriction normalized serum proline levels but did not improve cognitive deficits.
Implications:
- Early dietary intervention may normalize biochemical markers but not reverse established neurological damage.
- The findings suggest potential age-dependent modifications for proline oxidase activity.
- Further research is needed to understand the interplay between genetic factors and metabolic disorders in neurodevelopment.
Abstract:
A severe mentally retarded infant with type I hyperprolinemia associated with chromosomal abnormality is reported. The patient had a characteristic facial appearance of hyperprolinemia and suffered from convulsions after the age of 10 months. The child developed severe mental and motor retardation. The karyotype of the patient revealed partial duplication of the short arm in chromosome 10 using G banding techniques. The patient and her mother showed a fasting hyperprolinemia and an abnormal clearance curve after the proline load in the serum. The proline oxidase activities of the liver tissues obtained by biopsy in the patient was about 9% of those of controls. Kinetic studies and mixed experiments of the enzyme were with normal limits. Restriction of dietary proline at the age of 12 months revealed a prompt fall of the plasma levels of proline to the normal range, and a low proline diet was continued until the present time. During the period of dietary treatment, growth was satisfactory, but her mental development did not improve. From the developmental patterns of proline oxidase activities postnataldy, we speculated that restriction of dietary proline intake should be relieved with age.