Part of the excitement surrounding a heightened understanding of our genetic makeup is that we are beginning to learn what it really means to consider each patient as unique.
In the course of providing medical care for children, we often assess risk first and make management choices accordingly. Consider the 10-month-old infant who has a temperature of 39° C and no focal physical findings: She may be treated with antibiotics because she is at increased risk of bacteremia. The infant who presents in winter with rhinorrhea, wheezing, and a temperature of 38.6° C, on the other hand, is at low risk of serious bacterial infection and is treated accordingly.
Age, sex, season, lifestyle, geographythese are only some of the epidemiologic features we have learned to consider as we evaluate and manage patients. We also recognize that genetic factors put some patients at risk of specific conditions and complications. The child who has sickle cell disease, for example, is at greater-than-usual risk of some bacterial infections, and the child who has cystic fibrosis will not grow well unless she is provided with pancreatic enzyme replacement.
In caring for a generally healthy child, we often draw conclusions about genetic risk based on what we know about his or her family. For example, on the basis of what they've observed, many pediatricians suspect that a propensity for otitis media and middle ear effusion runs in familiesa suspicion that was corroborated recently in a study that demonstrated a strong genetic component to the risk of otitis media and middle ear effusion.1
Now, investigators from Finland may have discovered one reason for that genetic link: surfactant protein A. This protein plays a role in host defense in the lung and the eustachian tube and may, it turns out, be important in protecting children from acute otitis media.2 The investigators report that children who inherit certain genetically determined forms of surfactant protein A have an increased likelihood of recurrent otitis media. Perhaps we've been in error managing all children as though they are at identical risk of otitis media and its complications.
Understanding risk makes it possible to select the patients we will treat. It also makes it possible to recognize that what is appropriate, even essential, for one child may be unnecessary for most. Discoveries such as the link between surfactant protein A and otitis media allow us to do more than put a name on the reasons that certain children are at increased risk. They help us understand how those risks can be modified.
We now know, for instance, that susceptibility to thrombosis can be inherited, and that even young people who have such an inherited tendency are at risk. Identifying these children will allow pediatricians to counseleven more vigorously than usualagainst smoking and, in young women, against oral contraception, which might intensify the underlying genetic risk.
Genes are only one of many factors that can protect people or put them at risk. But it is the genetic makeup of the individual upon which all other influences must act. In turn, the risks associated with age, environment, and behavior are all modified by particular genes. Part of the excitement surrounding a heightened understanding of our genetic makeup is that we are beginning to learn what it really means to consider each patient as unique.
1. Casselbrant ML, Mandel EM, Fall PA, et al: The heritability of otitis media: A twin and triplet study. JAMA 1999;282:2125
2. Ramet M, Lofgren J, Alho OP, et al: Surfactant protein-A gene locus associated with recurrent otitis media. J Pediatr 2001;138:266
Julia McMillan. Editorial: Individualizing risk. Contemporary Pediatrics 2001;4:9.