Methods: African American and Caucasian families with multiple members affected by localized or generalized AgP were recruited in Virginia and Caucasian CP subjects and periodontally-healthy controls were identified in the population-based Study of Health in Pomerania (SHIP) in Germany. DNAs from saliva or blood were assayed for three SNPs in the coding region (changing amino acids) and one SNP in the promoter region of LTF using the TaqMan method. Data were analyzed by logistic regression both with adjustment for age, smoking and gender.
Results: The LTF Lys47Arg polymorphism (rs1126478) showed evidence of association with localized (but not generalized) AgP in African Americans but only in males (P=0.02). Association of this SNP in Caucasian AgP subjects was found only for generalized AgP, also only in males (P=0.006). In contrast, for CP a strong association with this SNP was found only in females (P=0.00009). SNP ALA29Thr (rs1126477) is located only 550 bp from Lys47Arg and genotypes are very strongly correlated. The associations are nearly identical and it is not statistically possible to distinguish which of these SNPs (or both of them) may be causal in driving the association. SNP rs1520483 located in the promoter region of the most common LTF transcript was strongly associated with generalized AgP in Caucasians (P=0.0001) of both genders. This SNP occurs at very low allele frequency in African Americans. No associations were observed for SNP Glu579Asp (rs2073495).
Conclusions: These findings demonstrate the diversity of molecular functions of LTF and the complex interactions of inherited variation with different subtypes of periodontitis, geography, race and gender.