Genetic Polymorphisms May Influence the Development and Healing of Sitting-Acquired Pressure Ulcers Following Spinal Cord Injury

Abstract

Sitting-acquired pressure ulcers (SAPUs) are serious secondary complications in individuals with spinal cord injury (SCI). The incidence of pressure ulcers in adults with SCI living in the community is more than 30% per year and up to 80% over a lifetime.1-3 They occur over the bony prominences of the pelvis, and multiple risk factors have been associated with their development and recurrence. One factor that has been associated with a higher rate of recurrence of SAPU is African American race,4 which suggests the possibility of a genetic predisposition to the development of ulceration. Studies on different types of chronic wounds, in particular venous leg ulcers, have found that there is an association between the development of the chronic wound and a number of genetic polymorphisms5-8 (Table 1). One of the polymorphisms has also been associated with impaired healing of chronic venous leg ulcers.9 Most of these polymorphisms are in genes that regulate the expression of different proteins. Table 1. Associations between genetic polymorphisms and venous leg ulcers Genetic polymorphisms are differences in the DNA sequences that occur between individuals, groups, or populations. The variation may occur in the coding region for a protein or may occur in a region that regulates protein expression. Single nucleotide polymorphism (SNP) is a source variance in a genome that is a single base mutation in DNA.10 SNPs are the most simple form and most common source of genetic polymorphism in the human genome (90% of all human DNA polymorphisms). The association of genetic polymorphisms with other types of chronic wounds raises the possibility that the same factors may be associated with the development of SAPUs following SCI. This concept is supported by the clinical observation that some individuals with the similar risk profile develop SAPUs while others are pressure ulcer free, suggesting an inherent predisposition. The association between race and ulcer recurrence after controlling for socioeconomic status strongly suggests a role for genetic factors. The objectives of this work within our research group have been to further examine associations between genetic polymorphisms and venous leg ulcers and more recently to assess associations with SAPUs following SCI.