# Heterozygous Hereditary Vitamin D-Dependent Rickets Type 2A (VDDR2A) in a Patient Presenting With Pseudoarthrosis

## TL;DR

A patient with a rare vitamin D disorder showed unusual symptoms, suggesting that a single gene variant can cause the condition.

## Contribution

Demonstrates that a heterozygous VDR variant can cause VDDR2A, challenging its typical autosomal recessive inheritance.

## Key findings

- A single heterozygous variant in the VDR gene was linked to VDDR2A symptoms.
- The case highlights variable presentation of VDDR2A beyond typical autosomal recessive patterns.
- The report emphasizes the role of vitamin D, calcium, and PTH in disease pathogenesis.

## Abstract

This case report is centered on an atypical presentation of Hereditary Vitamin D-dependent Rickets 2A (VDDR2A), a rare disorder caused by defects in the gene encoding the vitamin D receptor (VDR). While this disorder is primarily autosomal recessive in inheritance, this case demonstrates that a single heterozygous variant in the VDR gene could be linked to both phenotypic and laboratory manifestations of this condition. To understand the pathogenesis of this condition, one must know the typical roles of vitamin D, calcium, and parathyroid hormone (PTH) in maintaining homeostasis in the body. This case report focuses on the underlying pathogenesis of this disorder and demonstrates the variability in the ways this condition can present.