Nelson Textbook of Pediatrics 22nd Edition -- Autosomal recessive, IKBKAP (ELP1) mutation (9q31), Ashkenazi Jewish (carrier frequency 1/30). Alacrima (absence of emotional tears), absent fungiform papillae (smooth tongue), absent axon flare to histamine, autonomic crises (cyclic vomiting, hypertension, agitation), postural hypotension, scoliosis, recurrent aspiration pneumonia, renal disease.
๐ paeds.online -- Pakistan's Pediatric Platform| Feature | Details |
|---|---|
| Gene / Locus | IKBKAP (ELP1) on 9q31, AR |
| Population | Ashkenazi Jewish (carrier 1/30) |
| Alacrima | Absence of emotional tears (universal) |
| Tongue | Absent fungiform papillae (smooth, shiny) |
| Histamine test | Intradermal histamine โ absent axon flare (no surrounding redness) |
| Methacholine test | 2.5% methacholine conjunctival instillation โ miosis (denervation supersensitivity) |
| Deep tendon reflexes | Decreased or absent |
| Autonomic crises | Cyclic vomiting, hypertension, tachycardia, skin blotching, agitation |
| Orthostatic hypotension | Postural drop in BP without compensatory tachycardia |
| Scoliosis | Common, progressive |
| Renal disease | Chronic kidney disease due to vasomotor instability, hypertension |
| Aspiration pneumonia | Dysphagia, GERD, recurrent pneumonias |
Clonidine (ฮฑ2-agonist) 0.1-0.2 mg PO/IV -- reduces sympathetic outflow, hypertension.
Diazepam 0.2 mg/kg IV -- treats agitation, vomiting.
Carbidopa 1.5-2.5 mg/kg PO -- DOPA decarboxylase inhibitor, reduces autonomic crisis frequency.
IV fluids for dehydration, electrolyte imbalance.
Chronic prevention: Carbidopa, clonidine patch, diazepam as needed. Avoid triggers (stress, infection).