Additionally, reduction of the DARPP-32 protein, which is highly enriched in medium-sized spiny neurons and has been reported to be down-regulated concurrently with early neuronal dysfunction in the R6/2 mouse model of HD [25,26], was partially reversed in mouse brains by deletion of one Supt4h allele (Fig 4D). The gene discussed is PPP1R1B; the disease is ring chromosome 6.