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Two siblings with hypophosphatasia
Insights
This study reports on two siblings with hypophosphatasia, a rare genetic disorder affecting bone mineralization. Findings highlight severe skeletal abnormalities and suggest carrier status in family members.
Area of Science:
- Genetics
- Pediatrics
- Biochemistry
Background:
- Hypophosphatasia is a rare inherited metabolic bone disease characterized by defective bone mineralization.
- This study investigates a familial case of severe infantile hypophosphatasia.
Observation:
- Two siblings presented with severe skeletal abnormalities, including poor bone mineralization and rhizomelic micromelia.
- Autopsy revealed a small thoracic cage, membranous skull, and poorly ossified bones, consistent with rickets.
- Microscopic examination showed disturbed enchondral and membranous ossification.
Findings:
- Biochemical analysis revealed low serum alkaline phosphatase, high calcium, and normal parathyroid hormone (PTH).
- Family screening indicated that parents and a brother were carriers of hypophosphatasia.
- The study emphasizes the importance of biochemical markers in diagnosing hypophosphatasia.
Implications:
- This case highlights the severe clinical manifestations of hypophosphatasia and its genetic basis.
- Early diagnosis and genetic counseling are crucial for affected families.
- Understanding carrier status aids in reproductive planning and management of the disorder.
Abstract:
Two siblings with hypophosphatasia, one of whom was autopsied, were reported. The first case which was a product of a 26-year-old mother complicated by hydroamnios represented poor mineralization of the entire bones on X-ray examination and died shortly after birth. The second case weighing 1850 g delivered from the same mother had a rhizomelic micromelia and poor visualization of the skull, long bones and vertebral bones on X-ray at postmortem. The autopsy on the second case showed small thoracic cage with rachitic rosaries of ribs, membranous skull and poorly ossified vertebral and long bones. Microscopically, there was a marked disturbance of both enchondral and membranous ossifications similar to the histology of rachitis. A biochemical examination showed low alkaline phosphatase, high calcium and normal PTH in the serum. Further examination of their family revealed relatively low level of alkaline phosphatase of the parents and one of their brothers which suggsted they were carriers of hypophosphastasia. Previous reports on hypophosphatasia were reviewed and differential diagnosis of hypophosphatasia from the other congenital dwarfisms was discussed.