Introduction. Terminal and interstitial deletions of the distal segment of the long arm of chromosome 4 (Cr4q del) are not common genetic disorders. The severity of the phenotype is correlated with the size of the deletion because small deletions have little clinical impact, whereas large deletions are usually associated with multiple congenital anomalies, postnatal growth failure, and moderate to severe intellectual disability. Alteration in pain tolerance has not been included among these features, also in case of large deletions. The purpose of this report is to document a case of a child affected by interstitial Cr4q del, expressing pain insensitivity as clinical feature not previously described. We also offer a discussion on genetic disorders featuring pain insensitivity/indifference. Case report. A Caucasian girl aged 12 came to our observation for a developmental delay with multiple congenital abnormalities and moderate intellectual disability (IQ 47). A de novo interstitial Cr4 del between band q31.3 and q32.2 (Cr4 del q31.3 to q32.2) was found. The child also expresses no evidence of pain perception to injures which normally evoke pain. Consequently, she is affected by severe disability caused by painless injuries and self-injurious behaviours, such as excessive self-rubbing and scratching. The neurological examination manifested high pain threshold with preserved tactile sensitivity. Conclusions. This is the first report of pain insensitivity in a patient with a specific genetic deletion involving the interstitial region of the distal long arm of Cr4. Moreover, this report could serve as a useful model to better understand mechanisms of pain perception and its modulation.