Investigação familiar do raquitismo hipofosfatêmico ligado ao X-dominante no âmbito clínico-laboratorial

Abstract

Introduction: X-linked dominant hypophosphatemic rickets (XLH) has a worldwide prevalence of 1:20,000, lacking specific data in State of Rio de Janeiro (Brazil). Objectives: To analyze the familial occurrence and clinical-laboratory profile of 32 XLH patients in tertiary institutions in Rio de Janeiro. Methods: Observational, descriptive, cross-sectional study. Variables studied: demographic, clinical, laboratory, and radiographic characteristics; familial occurrence. Results: Study with 32 diagnosed patients (13 index cases, 19 in families. Median age: 25 years; symptom onset: 18 months; average diagnosis: 4 years and 5 months. All of them with short stature, 30/32 with limb deformities, and 29/32 with genu varum. Eighteen patients had hypophosphatemia (mean: 2.6 mg/dl ± 1.1). PHEX gene sequencing identified pathogenic variants in 93%. Discussion: XLH is poorly understood in Brazil, with only 32 cases identified in Rio de Janeiro, mainly in the metropolitan region. The average delay in diagnosis, up to 4 years and 5 months, highlights the urgency of the disease awareness and implementation of specific protocols. Clinical, laboratory, and genetic findings reinforce the complexity of the disease, emphasizing the need for effective strategies for diagnosis and treatment. Conclusion: The metropolitan region is the epicenter of the cases, with 62.5% of familial occurrence. The wide age range of affected individuals, from 5 to 78 years, reflects the chronicity of the condition. Late diagnosis is a pressing issue, with clinical and radiographic findings consistent with the literature. Additionally, PHEX gene sequencing revealed the presence of novel pathogenic variants in 53% of the cases, indicating notable genetic variability.