Calcification of the basal ganglia is a nonspecific finding that can occur in the context of certain infectious, metabolic and genetic syndromes. It may simply constitute a benign incidental finding (around 1% of CT scans performed for other reasons in people over 60 years of age), the sequel of a connatal infection, but there is an associated clinical picture, not explained by other causes and particularly in the context positive family history, the possibility of a genetic study should be considered.
There are two conditions that we have considered for addressing this panel:
In childhood, Aicardi-Goutières syndrome (AGS) is an early-onset encephalopathy that presents with cerebral atrophy, leukodystrophy and characteristically calcifications of the basal ganglia and elevated levels of interferon in the CSF. There are several genes described (RNASEH2A<, RNASEH2B, RNASEH2C, SAMHD1, REX1, ADAR and IFIH1), with which a diagnostic yield of 90-95% of suspected AGS cases is achieved (Crow et al., 2015). Since the original description (Aicardi and Goutières, 1984), the phenotypic spectrum has been expanding, which must be taken into account particularly in later presentation forms.
In adults around the 3rd-5th decade of life, one might think of idiopathic calcification of the basal ganglia (Fahr’s disease): an autosomal dominant condition, usually of familial onset, characterized by symmetrical calcification in the basal ganglia and other regions of the brain. The symptoms can range from asymptomatic stages to a wide spectrum of neuropsychiatric symptoms. The genes involved to date are SLC20A2, XPR1, PDGFB and PDGFRB. More recently, the involvement of 2 additional genes, PCDH12 and MYORG, of autosomal recessive transmission, has been described.