J Periodont Res. 2018;1–8. wileyonlinelibrary.com/journal/jre | 1 © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd 1 | INTRODUCTION Aggressive periodontitis (AgP) is a complex heterogeneous disease that occurs in systemically healthy individuals and is character- ized by the inflammation and severe destruction of periodontal tis- sues and alveolar bone. 1-3 AgP was formerly known as “early-onset periodontitis,” as the disease has an early age of onset and is com- monly seen in younger adults. 4 The prevalence of AgP is reported to be between 0.1% and 15% among different ethnic groups, 5 where it is significantly higher in people of African origin compared to Caucasians and Hispanics. 5 Risk factors for AgP include microbiolog- ical and environmental factors. 1,2 The main reason for AgP seems to Accepted: 6 May 2018 DOI: 10.1111/jre.12580 ORIGINAL ARTICLE Consanguinity increases the risk for aggressive periodontitis M. Çalışır Department of Periodontology, Faculty of Dentistry, Adiyaman University, Adiyaman, Turkey Correspondence Metin Çalışır, Department of Periodontology, Faculty of Dentistry, Adiyaman University, Adiyaman, Turkey. Email: calisir_metin@hotmail.com Background and Objective: Genetic predisposition is an important factor for develop- ing aggressive periodontitis (AgP); however, previous studies only focused on individ- ual families where consanguineous marriages have not been considered. Thus, there is a debate in the understanding of the genetic features of this disease. The present study aims to compare the genetic features of AgP in individuals with and without history of consanguineous marriages. Material and Methods: Thirty-three probands from 16 pedigrees with history of con- sanguineous marriage and 17 pedigrees without history of consanguineous marriage were analyzed in terms of heritability of AgP. Detailed clinical evaluations of the probands showing their periodontal health and their family medical histories were ob- tained. The gingival index, plaque index, bleeding on probing, suppuration, probing pocket depth and clinical attachment level data were analyzed and compared between groups. The gender differences were also taken into account to determine the mode of inheritance of AgP. Results: The gingival index, bleeding on probing, suppuration, probing pocket depth and clinical attachment level scores were significantly different between the affected and unaffected groups for both genders, which were consistent with the diagnosis of AgP. Strikingly, when the consanguineous group and the non-consanguineous group were compared, the siblings of the consanguineous group displayed approximately 8 times more prevalence of AgP (15.15%) compared to the siblings of the probands in the non-consanguineous group (1.89%) (P = .022). In addition, the mode of transmission of the disease was found to fit better to the autosomal recessive inheritance pattern. Conclusion: Current findings indicate that AgP is segregated on autosomal chromo- somes and consanguineous marriage increases the likelihood of developing this disease. KEYWORDS aggressive periodontitis, consanguinity, human genetics, periodontal index