Clusters of Autoinmune Diseases in Children

Cristian Seiltgens; Mirentxu Iruretagoyena; Patricia Melendez; Maria Jesus Ponce; Eduardo Talesnik; Cecilia Mendez; Claudia Godoy; Alejandro Martinez-Aguayo; Isabel Hogdson; Paul Harris; Juan Carlos Gana; Francisca Riera; Hernan Garcia; Andreina Cattani; Arturo Borzutzky

Background: Autoimmune diseases (AIDs) have familial aggregation and frequently share a common genetic background, but few studies have evaluated autoimmune clusters in children with AIDs and their families.

Objective and hypotheses: To identify clusters of AIDs in children and their first-degree relatives.

Method: A cross-sectional study was performed in subjects with an AID of pediatric onset (<18 years) recruited at Pediatric Endocrinology, Rheumatology, and Gastroenterology Clinics at the Health Network of the Pontificia Universidad Católica de Chile School of Medicine. Clusters of AIDs were identified by K-means cluster analysis.

Results: 191 subjects with pediatric AIDs were included, of which 45 (24%) had polyautoimmunity. Mean age was 12.1 years (range 1–19) and 68% were female. Most frequent AIDs were JIA (36%), AITD (25%), T1D (19%), uveitis (8%), celiac disease (6%), and vitiligo (6%). 59% of subjects with pediatric autoimmunity had first-degree relatives with an AID. Five clusters of AID were identified in families of children with autoimmunity (Table 1). Among the 45 subjects with pediatric polyautoimmunity, four clusters of AIDs were identified (Table 2).

**Table 1.** Clusters of autoimmune diseases among children with autoimmunity and their first-degree relatives.
Cluster	Number of cases	Autoimmune diseases (Descending order of relevance)
1	94	Juvenile idiopathic arthritis
		Connective tissue diseases
		Autoimmune thyroid disease
2	29	Juvenile idiopathic arthritis
		Psoriasis
		Autoimmune thyroid disease
3	31	Type 1 diabetes
		Autoimmune thyroid disease
		Celiac disease
		Psoriasis
4	25	Autoimmune thyroid disease
		Type 1 diabetes
		Vitiligo
		Connective tissue diseases
5	10	Celiac disease
		Autoimmune thyroid disease
		Type 1 diabetes
		Autoimmune hepatitis
		Juvenile idiopathic arthritis

**Table 2.** Clusters of autoimmune diseases among children with pediatric polyautoimmunity.
Cluster	Number of cases	Autoimmune diseases (Descending order of relevance)
1	4	Connective tissue diseases
		Autoimmune thyroid disease
		Juvenile idiopathic arthritis
2	11	Type 1 diabetes
		Autoimmune thyroid disease
		Celiac disease
		Inflammatory bowel disease
		Immune thrombocytopenic purpura
3	10	Autoimmune thyroid disease
		Vitiligo
		Juvenile idiopathic arthritis
		Celiac disease
		Scleroderma
4	18	Juvenile idiopathic arthritis
		Uveitis
		Psoriasis
		Vitiligo
		Alopecia Areata
		Autoimmune Hepatitis

Conclusion: AIDs in affected children and their families may be grouped into well-defined clusters suggesting a common etiopathogenesis among diseases grouped in each cluster.

ESPE Abstracts

P1-P698