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Keratomalacia in a child with familial hypo-retinol-binding proteinemia
T Matsuo1, N Matsuo, F Shiraga
1Department of Ophthalmology, Okayama University Medical School, Japan.
Insights
Familial hypo-retinol-binding proteinemia, a rare genetic condition, was identified in a child with keratomalacia. This condition, characterized by low retinol-binding protein (RBP) levels, predisposed the child to vitamin A deficiency symptoms.
Area of Science:
- Biochemistry
- Genetics
- Ophthalmology
Background:
- Retinol-binding protein (RBP) is crucial for vitamin A transport.
- Keratomalacia results from vitamin A deficiency or protein-calorie malnutrition.
- RBP production can be impaired in malnutrition.
Observation:
- A 19-month-old child developed keratomalacia despite adequate nutrition during measles.
- The patient, her mother, and sister exhibited persistently low retinol and RBP levels.
- These low levels were unresponsive to dietary and oral vitamin A supplementation.
Findings:
- The family presented with familial hypo-retinol-binding proteinemia, a novel finding.
- This genetic condition leads to approximately half the normal levels of retinol and RBP.
- Affected individuals showed normal liver function, other proteins, and fat-soluble vitamins.
Implications:
- Familial hypo-retinol-binding proteinemia may predispose individuals to vitamin A deficiency disorders like keratomalacia, especially during infections.
- This condition is likely inherited, with family members potentially being heterozygous carriers of a defective RBP gene.
- Further research is needed to understand the genetic basis and clinical management of this rare disorder.
Abstract:
Retinol-binding protein (RBP) is a plasma protein with a molecular weight of 21,000 synthesized in the hepatocytes, binding with retinol (vitamin A), and transporting retinol to peripheral tissues. Keratomalacia is caused by a deficiency of vitamin A itself and/or protein-calorie malnutrition. In the latter condition, production of RBP is inhibited. We report herein familial hypo-retinol-binding proteinemia in a child aged 19 months who developed keratomalacia during measles infection in spite of good nourishment. To the best of our knowledge this is the first description of such a case. The patient, her sister and mother showed persistent low levels, about half the normal levels, of retinol and RBP which were unresponsive to oral vitamin A and protein-rich diet. They had normal liver function tests, normal serum levels of other proteins and fat-soluble vitamins and lipids. This hypo-retinol-binding proteinemia was thought to predispose the child to develop keratomalacia during measles. Family members would be heterozygous with one normal RBP gene and one defective RBP gene.