Systemic Lupus Erythematosus or Aicardi-Goutières Syndrome?

In this issue of Neuropediatrics, Dale et al report on a puzzling familial disorder in two brothers born to consanguineous (first cousins) parents, which they consider as infantile systemic lupus erythematosus (SLE). The diagnosis was based on a characteristic autoantibody profile that developed between the ages of 2 and 4 years in children with an early encephalopathic disease with CNS calcification and, in one infant, some evidence of multisystemic involvement. In addition, both infants had, from a few months of age, a rash on the extremities and the older developed nephritis in the course of terminal streptococcal septicemia. The familial character of the disease, its very early onset and the clinical and imaging features clearly differ from those reported in both neonatal and infantile SLE, even though neurological complications have been described in a few such cases [[ 3 ], [ 7 ]]. The features of the two cases of Dale et al, on the other hand, fit nicely those of the Aicardi-Goutières syndrome (AGS), a rare syndrome characterized by a probably autosomal recessive inheritance with onset in early life, progressive course with microcephaly, progressive and severe cerebral dysfunction, calcification of the basal ganglia, chronic CSF lymphocytosis without evidence of infection and elevated levels of interferon alpha in CSF and sometimes also in blood [[ 6 ]]. Unfortunately, the absence of CSF and interferon studies precludes a definitive conclusion. The cutaneous lesions observed by Dale et al are similar to those recently reported in several cases of AGS and involve especially the extremities [[ 6 ], [ 9 ]]. We have recently seen a patient with an ear lesion closely resembling that illustrated in Dale's article, including association with severe lesions of the extremities. Such cutaneous lesions seem relatively common in AGS although their severity is variable, from puffy fingers to marked damage with evidence of vasculitis by biopsy (personal communication from Professor Ponsot, Paris). The clinical course of AGS is also variable, some patients surviving into late childhood or even early adulthood [[ 6 ]]. It seems that the microcephaly-intracranial calcification syndrome (MICS) is probably closely related to AGS and that both types can occur in the same sibship [[ 6 ], [ 8 ]] as was also the case in the family reported by Dale et al. Another familial disease with basic similarity to AGS has been described in Cree Indians in Quebec [[ 2 ]] and in one such case, an elevated level of interferon alpha has been demonstrated [[ 6 ]]. Interestingly, affected Cree infants suffer from repeated infections. This clinical variability of expression might well result from genetic heterogeneity as suggested by both haplotype [[ 5 ]] and linkage [[ 4 ]] studies. A linkage to chromosome 3 p was recently found in 3 of 8 families including cases of both AGS and MICS [[ 4 ]], again suggesting that AGS, MICS and the Cree Indian disease are all members of a group of disorders featuring a microangiopathy that has been demonstrated in the CNS at autopsy [[ 1 ], [ 6 ]] but must also be present in other tissues, especially in the skin. There is experimental evidence that increased interferon alpha may be directly involved in the mechanism of vasculitis and is probably one cause of encephalopathy: transgenic mice receiving astrocyte-targeted interferon alpha develop a progressive encephalopathy with calcification of the basal ganglia and vasculitis that bears a close resemblance to the neuropathological lesions found in AGS patients. The resulting encephalopathy is probably of hypoxic-ischemic origin as seems also to be the case in the human disease. Clearly, the conditions of this group are associated with a dysfunction of the immune system whose severity and type may vary. The remarkable course of the patients of Dale et al suggests that, in some cases, the initial immune dysfunction may later evolve into a clear picture of SLE. As indicated in Dale's paper, recent publications suggest that certain genetic immunological deficits can predispose to SLE, e.g. deficiency of C1q component in adults [[ 10 ]]. Whether the cases of Dale et al represent a separate subgroup within the AGS/MICS group will have to await further studies of the immune mechanisms in this group, especially systematic research of autoantibodies.

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