HELIX syndrome (HS) associates hypohidrosis, electrolyte imbalance, lacrimal gland dysfunction, ichthyosis, and xerostomia. It results from bi-allelic mutations in the CLDN10 gene, encoding claudin-10, a tight junction protein. Patient 1 (M, 28y) was referred for xerostomia, alacrima, hypohidrosis, severe intolerance to heat and polyuria. Increased creatininemia (126µmol/l), glomerular filtration rate (GFR; 54ml/min/1.73m2), and hypokalemia (3.2 mmol/l) with hyperaldosteronism were found.Decreased urinary magnesium excretion (3.5%) was associated to normal magnesemia (1.10mmol/l), hyperparathyroidism, normocalcemia, hypocalciuria, and vitamin D deficiency. He was the first child of a healthy, first cousin Malian parents. Among his 9 siblings, 5 presented with similar symptoms and manifestations. Increased creatinine and hypokaliemia were detected in 4/5. A homozygous disease-causing mutation in CLDN10 was identified in 5 patients. Patient 7 (M, 34-year) is the first child of first cousin Dutch parents. His phenotype was similar to patient 1. Scintigraphy of salivary glands did not show any excretion. Both increased creatininemia (133µmol/l) and GFR (62ml/min/1.73m2) were noted. He was homozygous for a CLDN10 mutation. Here we report: i) 7 patients with HELIX syndrome from 2 unrelated families with 2 unreported mutations in CLDN10. Mild xerosis and hypohidrosis starting early in life justify renal explorations that can be life-threatening.

ESDR085 - Hypohidrosis, ichthyosis and hypokalemia: HELIX syndrome

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING