Extreme conditions like savantism, autism or synaesthesia, which have a neurological 2AH, UK basis, challenge the idea that other minds are similar to our own. In this paper we report a single case study of a man in whom all three of these conditions co-occur. We suggest, on the basis of this single case, that when savantism and synaesthesia co- occur, it is worthwhile testing for an undiagnosed Autism Spectrum Condition (ASC). This is because savantism has an established association with (...) ASC, and the combination of ASC with synaesthesia may increase the likelihood of savantism. The implications of these conditions for philosophy of mind are introduced. (shrink)

Synaesthesia is a neurodevelopmental condition characterised by anomalous sensory perceptions and associated alterations in cognitive function. This chapter summarises what is known about the familial transmission of synaesthesia and its genetic underpinnings. Early familiality studies showed evidence for a strong genetic predisposition, a highly skewed female: male ratio, and an absence of male-to-male transmission. These patterns supported an early hypothesis of a single-gene X-linked dominant mode of inheritance with male lethality. Subsequent analyses in larger samples indicated that the mode of (...) inheritance was likely to be more complex, with both the strong female skew and absence of male-to-male transmission brought into question. We review in detail the first whole genome linkage scan for auditory-visual synaesthesia and a subsequent family linkage study on coloured sequence synaesthesia. Together these results suggest linkage to five chromosomes but give no support for linkage to the X-chromosome. We discuss candidate genes within these regions and potential implications for the aetiology of synaesthesia. We also discuss the implications of these pioneering genome scans for our understanding of synaesthesia and of how different synaesthetic phenotypes may arise from different genetic predispositions interacting with other genes and with the environment. (shrink)