Table 1.

Alopecia areata comorbidities suggested by big data

Disease/trait category	ICD co-occurrence (Rzhetsky et al. 2007)	PheWAS (phewascatalog.org)	C3H/HeJ (phenome.jax.org)
Autoimmune	Rheumatoid arthritis	Rheumatoid arthritis	Prone to colitis
	Multiple sclerosis	Multiple sclerosis	Thyroid hormone abnormalities
	Systemic lupus Erythematosus	Systemic lupus Erythematosus
	Type 1 diabetes mellitus	Type 1 diabetes mellitus
	Psoriasis	Psoriasis
		Ulcerative colitis
		Grave’s disease, Thyroiditis
Inflammatory Metabolic	Allergic rhinitis	Allergic rhinitis	Elevated total cholesterol
	Hypersensitivity angiitis	Asthma	Elevated phospholipids
	Disorders of lipid metabolism	Disorders of lipid metabolism	Decreased circulating alanine transaminase
	Type 2 diabetes mellitus	Type 2 diabetes mellitus
	Cholelithiasis		Elevated heme oxygenase
	AA metabolism (aromatic) acanthosis nigricans
Neuropsychiatric	Attention deficit disorder	Attention deficit disorder	Prone to impulsivity, anxiety
	Epilepsy	Epilepsy	Absence seizures (Gria4spkw)
	Depression		Attenuated response to tactile and thermal stimulation
	Bipolar disorder
	Migraine		Disruptions in social behavior
Cardiovascular		Atherosclerosis	Abnormal ECG findings
		Myocardial infarction
		Blood pressure
		Heart failure

Three datasets were queried to identify conditions and traits that could be associated with AA. The table reports only conditions related to the four categories of focus in our commentary. Additional traits may be found in each source. ICD co-occurences were identified in an analysis of 161 ICD codes in 1.5 million patient records (Rzhetsky et al, 2007). We identified 28 SNPs associated with AA in our recent meta-analysis in the PheWAS catalogue and extracted all reported ICD code associations. For the C3H/HeJ, we manually curated a list of all traits for which this strain was reported to be an outlier.