Journal of IiME Volume 2 Issue 2 www.investinme.org Family Illnesses Among People with ME/CFS: Blood Versus Non-Blood Relatives (continued) Endicott (1999) reported a higher rate of autoimmune disorders in parents of persons with ME/CFS whereas Torres-Harding et al. (2005) did not find any differences in familial autoimmune vulnerabilities among persons with ME/CFS and a control group. In the current study, we examined two autoimmune diseases: Lupus and Multiple Sclerosis. Whereas a significant difference was found for Lupus, there were no significant differences in the familial history of Multiple Sclerosis between blood relatives and nonblood relatives. Low power and small sample sizes might have been the reasons for not being able to detect statistical differences for Multiple Sclerosis. Certainly, there is a need for larger samples to determine if these findings are replicated by other investigators. Both Endicott (1999) and Walsh et al. (2001) found that persons with ME/CFS were more likely to report chronic fatigue-like illnesses than control groups. In contrast, TorresHarding et al. (2005) found no significant differences in family background for these illnesses. In the present study, there were more familial reports of ME/CFS for blood relatives than non-blood relatives indicating interesting familial links predisposing individuals toward the development of ME/CFS. Many studies have documented that Fibromyalgia tend to co-occur with ME/CFS (Brown & Jason, 2007; Jason et al., 2000; Jason et al., 2001) but little is known about familial history of Fibromyalgia. The current study found significantly higher rates of familial Fibromyalgia history among blood relatives than non-blood relatives suggesting other predisposing factors in the development of ME/CFS. The current study was limited by several factors, including the assessment of only five familial illness histories. It is possible that there may be other illnesses that were not assessed in this study. In addition, recall bias tends to impact the self report data, and it is certainly possibly that individuals tend to recall illnesses of blood relatives more than non-blood Invest in ME (Charity Nr. 1114035) relatives’ illnesses. In addition, this study did not include reports of the demographic information of the relatives, which could have helped to examine other possible sociodemographic factors. The lack of a matched control group by age and race is another limitation of this study. The results may have been impacted by the lack of equal number of blood and non-blood relatives. It is unclear whether people with ME/CFS have more blood or non-blood relatives, so it is at least possible that the results were influenced by this finding. The most serious potential confound in this study was that it could be argued that there are more blood relatives than non-blood relatives. Yet the findings, particularly for diabetes, would even take this into account. If 8% of the population has diabetes (American Diabetes Association, 2008), than among the 114 people in the sample with ME/CFS, there would be 228 parents, and about 18 expected cases of diabetes among these 228 parents. However, among the fathers and mothers of the sample, there were 34 cases of diabetes (and all of these cases came from blood relatives), suggesting a rate more than double what would have been expected, which would have been 18. In addition, if one were to take all cases of non-blood relatives, there were only 5 cases of diabetes. In contrast, there were 75 cases for those with blood relatives. This difference is large, but one might still question whether there were more biological relatives than nonbiological relatives. This concern could also be addressed if one were to limit the number of biological relatives for each person with ME/CFS. For example, if one were to just focus on one type of blood relative, the father of the person with ME/CFS, and compare the 114 fathers of the people with ME/CFS to all the non-blood relatives of the 114 people with ME/CFS, there certainly would be more people in the non-blood group than the blood group. Even though in this comparison there were more non-blood relatives, we only (continued on page 10) Page 9/74

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