MON-759 - Patient Experience and Diagnostic Journey in Autosomal Dominant Hypocalcemia Type 1: Insights from in-Depth Patient Surveys

Autosomal dominant hypocalcemia type 1 (ADH1) is a rare genetic disease caused by gain-of-function variants in the calcium-sensing receptor gene (CASR). This leads to chronic hypoparathyroidism characterized by hypocalcemia, typically hypercalciuria, low parathyroid hormone levels, and associated complications. Severity of clinical symptoms varies among patients, but despite the lifelong nature of the disease, the lived experiences of people with ADH1 remain poorly characterized.

An online, cross-sectional survey (May–October 2025) was conducted in people with ADH1 and/or their caregivers aged ≥18 years living in the USA. The survey explored experiences of diagnosis, treatment, and living with ADH1 long-term. Quantitative data were characterized using descriptive statistics, and qualitative data were thematically analyzed.

In total, 22 participants (91% female; mean age, 37 years) completed the survey. Symptom onset before 1 year of age was reported by 41% of respondents. All participants had molecular confirmation of ADH1, except one with unknown status.

Diagnostic delays were common: 41% of respondents had required >30 medical appointments before diagnosis was confirmed, reflecting the complexity of the diagnostic journey. Although half of respondents visited 1 healthcare professional, 33% consulted ≥2 healthcare professionals before referral to an endocrinologist. Most received a diagnosis after seeing a single endocrinologist; however, 27% required consultations with ≥4, underscoring the challenges in recognition of ADH1.

Concerns about long-term complications and inadequate symptom management on current treatment were reported by 36% of respondents. Treatment burden was considerable, with 23% of respondents taking >10 pills daily. Emergency care visits were frequent (45% of respondents reported ≥2 visits over the past 2 years), primarily due to tetany.

Beyond physical health, the most common long-term impact of living with ADH1 was on emotional/mental health in 46% and on finances in 46% of respondents. Additionally, 32% of people with ADH1 reported a “poor” or “very poor” quality of life. Analysis of open-ended responses identified 2 key themes: concern about passing ADH1 to future generations and the psychosocial burden of managing a rare, poorly understood disease. Two respondents reported being largely asymptomatic, aside from occasional complications and treatment-related challenges.

ADH1 imposes a challenging medical and psychosocial burden on patients and their families. These findings provide actionable insights to inform care improvements and to support the development of targeted interventions that may ultimately improve the health and well-being of people living with ADH1.

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