Epidemiology and Genetics of Achalasia

Associated with conditions like Parkinson's disease, Allgrove syndrome, and Down syndrome
Familial achalasia is reported, including one family with autosomal dominant pattern
Polymorphisms in nitric oxide synthase gene and interleukins (IL-23 and IL-10) have been investigated.

Pathophysiology

Associated with functional loss of myenteric plexus ganglion cells in the distal esophagus and lower esophageal sphincter
Consequences
- Dysfunction of inhibitory postganglionic neurons in these areas
- Impaired relaxation of the lower esophageal sphincter
- Potential hypercontractility of the distal esophagus
- Rapidly propagated contractions in the distal esophagus
- Persistent longitudinal muscle contractions and esophageal shortening
Potential causes
- Exact cause is unknown
- May be an autoimmune process triggered by an indolent viral infection (herpes, measles) in genetically susceptible individuals
- Higher prevalence of concomitant autoimmune diseases and serum neural autoantibodies in achalasia patients
- Can be a manifestation of Chagas disease, caused by Trypanosoma cruzi parasite

	Increase LES Pressure	Decrease LES Pressure
Hormones/peptides	Gastrin	CCK
	Motilin	Secretin
	Substance P	Somatostatin
		Vasoactive intestinal peptide
Neural agents	α-Adrenergic agonists	α-Adrenergic antagonists
	β-Adrenergic antagonists	β-Adrenergic agonists
	Cholinergic agonists	Cholinergic antagonists
Foods and nutrients	Protein	Chocolate
		Fat
		Peppermint
Other factors	Antacids	Barbiturates
	Baclofen	Calcium channel blockers
	Cisapride	Diazepam
	Domperidone	Dopamine
	Histamine	Meperidine
	Metoclopramide	Morphine
	Prostaglandin F₂α	Prostaglandins E₂ and I₂
		Serotonin
		Theophylline

Achalasia is characterized by progressive dysphagia to both solids and liquids, which is the hallmark symptom of the condition.
Younger patients exhibit higher rates of heartburn and chest pain compared to older patients.