Rare causes of pediatric primary adrenal insufficiency: Data from a large nationwide Tunisian cohort.

CONTEXT: Primary adrenal insufficiency (PAI), a rare and potentially life-threatening disorder, involves genetic factors in over 80% of pediatric cases. Congenital adrenal hyperplasia (CAH) is common, while the prevalence of other genetic factors varies between countries.

OBJECTIVE

This study investigated the clinical and molecular genetic characteristics of a Tunisian PAI sub-cohort. Identifying causal variants is crucial for patient care, genetic counseling, follow-up and preventing complications. Determining variant prevalence will help in shaping a cost-effective molecular strategy in a country with limited resources.

PATIENTS AND

METHODS

Seventy-four patients from 65 families, with suspected congenital PAI, excluding CAH and autoimmune disease, were recruited. Clinical details were assessed by endocrinologists. Genetic analysis used a candidate gene approach (AAAS, ABCD1) and/or targeted enrichment with focused gene panels and next-generation sequencing (NGS). The pathogenicity of rare variants was assessed on in silico analysis.

RESULTS

The study achieved a diagnostic yield of 86% (56/65 families), confirming 45 patients with Allgrove syndrome (Triple A) and identifying 12 boys with adrenoleukodystrophy. The recurrent Maghreb variant (c.1331+ 1G>A) was identified within the AAAS gene. NGS revealed additional defects, including AAAS and ABCD1 variants in atypical cases (n=3). Other etiologies included MC2R (n=1), NNT (n=1), STAR (n=2, 1 family), MCM4 (n=1) variants; 14% remained undiagnosed, some with variants of uncertain significance.

CONCLUSION

This study of Tunisia's largest PAI cohort confirmed the efficacy of the candidate gene approach. NGS significantly increased diagnostic yield (11%) and identified candidate variants. Achieving molecular diagnosis in almost 90% of children has implications for patient management, genetic counseling, monitoring and the prevention of complications.