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Gm and Km allotypes and typhoid fever
P Herrera1, M Arcos-Burgos, C Y Valenzuela
1Departamento de Pediatría, CEC, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
Insights
Children with typhoid fever showed a higher frequency of specific immunoglobulin G heavy chain (Gm) haplotypes compared to healthy children. These findings suggest a potential genetic link to typhoid susceptibility in this population.
Area of Science:
- Immunogenetics
- Infectious Diseases Epidemiology
Background:
- Immunoglobulin allotypes (Gm and Km) are genetic markers of the heavy and light chains of antibodies.
- Understanding genetic factors influencing susceptibility to infectious diseases like typhoid fever is crucial for public health.
- Previous research has explored associations between Gm and Km allotypes and various diseases, but data on typhoid fever in specific populations remain limited.
Observation:
- A study was conducted on children from Santiago, Chile, belonging to low and low-middle socioeconomic strata.
- Participants were categorized into three groups: children with typhoid fever (Cases), healthy children (Con-1), and children with fever but no Salmonella infection (Con-2).
- Immunoglobulin Gm and Km allotypes were determined for all participants.
Findings:
- Children with typhoid fever (Cases) exhibited a significantly higher frequency of the [f;(-);b1,b3 or 3;(-);5,13] G1m, G2m, G3m haplotype compared to both control groups (Con-1 and Con-2).
- No significant differences were observed in Gm haplotype or Km allele frequencies between the two control groups (Con-1 and Con-2).
- The Con-1 group deviated from Hardy-Weinberg equilibrium for Km, specifically due to a deficiency in Km 1-1 homozygotes, indicating a potential population-specific genetic pattern.
Implications:
- The observed higher frequency of a specific Gm haplotype in children with typhoid fever suggests a potential genetic predisposition or association with increased susceptibility to Salmonella Typhi infection.
- The differences in Gm haplotype frequencies may contribute to understanding the varying susceptibility to typhoid fever within the Chilean population, considering their ethnic background.
- Further research is warranted to elucidate the functional mechanisms by which these immunoglobulin allotypes might influence immune responses to Salmonella Typhi and to validate these findings in broader populations.
Abstract:
Gm and Km allotypes of immunoglobulins were determined in children with typhoid fever (Cases), in children without infectious diseases (Con-1), and in children with fever but no Salmonella in their blood or bone marrow (Con-2). Children were sampled from the urban population of Santiago; and they belonged to the low and low-middle socioeconomic strata. Cases had a higher frequency of [f;(-);b1,b3 or 3;(-);5,13] G1m, G2m, G3m haplotype than Con-1 and Con-2. Con-1 and Con-2 did not differ in their Gm haplotype or Km allele frequencies, but they differed in phenotype distribution. Con-1 deviated from Hardy-Weinberg equilibrium for Km due to a lack of Km 1-1 homozygotes. The relationship among these results, the ethnic origin of Chileans, and the differential susceptibility to typhoid fever are discussed.