Systemic
Fatigue in SLE is probably multifactorial and has been related to not only disease activity or complications such as anemia or hypothyroidism, but also to pain, depression, poor sleep quality, poor physical fitness and lack of social support. Causes
SLE is presumably caused by a genetic susceptibility coupled with an environmental trigger which results in defects in the immune system. One of the factors associated with SLE is vitamin D deficiency. Genetics
SLE does run in families, but no single causal gene has been identified. Instead, multiple genes appear to influence a persons chance of developing lupus when triggered by environmental factors. HLA class I, class II, and class III genes are associated with SLE, but only classes I and II contribute independently to increased risk of SLE. Other genes which contain risk variants for SLE are IRF5, PTPN22, STAT4, CDKN1A, ITGAM, BLK, TNFSF4 and BANK1.Some of the susceptibility genes may be population specific. Genetic studies of the rates of disease in families supports the genetic basis of this disease with a heritability of >66%. Identical (monozygotic) twins were found to share susceptibility to the disease at >35% rate compared to fraternal (dizygotic) twins and other full siblings who only showed a 2–5% concordance in shared inheritance.Since SLE is associated with many genetic regions, it is likely an oligogenic trait, meaning that there are several genes that control susceptibility to the disease.SLE is regarded as a prototype disease due to the significant overlap in its symptoms with other autoimmune diseases.
Prurigo pigmentosa is a rare skin condition of unknown cause, characterized by the sudden onset of erythematous papules that leave a reticulated hyperpigmentation when they heal. : 57  The condition has been associated with a strict ketogenic diet in case reports in the medical literature. It was first reported by Masaharu Nagashima in 1978. Research has shown that it may be caused by gut bacteria dysbiosis as a result of ketosis. See also
Pruritus
Skin lesion
Masaharu Nagashima

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