A further case of 3q29 deletion, in a 13-year-old boy, is described and compared with previous reports. Our case shares a number of dysmorphic and neurodevelopmental features with previously reported individuals with 3q29 microdeletion and is the second reported case with deceleration in head growth--which may be a useful diagnostic clue. Novel features, which may expand the phenotype, include nasal voice, six lumbar vertebrae, lower limb contractures and cerebral sigmoid venous thrombosis. Additionally, cases with cytogenetically visible terminal 3q deletions are reviewed.