Unravelling Genetic Factors Underlying Corticobasal Syndrome: A Systematic Review

Abstract

Corticobasal syndrome (CBS) is an atypical parkinsonian presentation characterized by heterogeneous clinical features and different underlying neuropathology. Most CBS cases are sporadic; nevertheless, reports of families and isolated individuals with genetically determined CBS have been reported. In this systematic review, we analyze the demographical, clinical, radiological, and anatomopathological features of genetically confirmed cases of CBS. A systematic search was performed using the PubMed, EMBASE, and Cochrane Library databases, included all publications in English from 1 January 1999 through 1 August 2020. We found forty publications with fifty-eight eligible cases. A second search for publications dealing with genetic risk factors for CBS led to the review of eight additional articles. GRN was the most common gene involved in CBS, representing 28 out of 58 cases, followed by MAPT, C9ORF72, and PRNP. A set of symptoms was shown to be significantly more common in GRN-CBS patients, including visuospatial impairment, behavioral changes, aphasia, and language alterations. In addition, specific demographical, clinical, biochemical, and radiological features may suggest mutations in other genes. We suggest a diagnostic algorithm to help in identifying potential genetic cases of CBS in order to improve the diagnostic accuracy and to better understand the still poorly defined underlying pathogenetic process.

Keywords: CBS; atypical parkinsonism; corticobasal degeneration; corticobasal syndrome; genetics.

Figure 1

Histograms showing the frequency of motor (A) and cognitive (B) features in patients with CBS associated with mutations in GRN, MAPT, C9ORF72, and PRNP. The asterisk (*) marks clinical features that were statistically different between GRN patients and non-GRN cases, as reported in Table 2.

Figure 2

Diagnostic algorithm for screening genetic causes of CBS.