A 23‐year follow‐up of a male with Hajdu‐Cheney syndrome due to NOTCH2 mutation

We present a natural history of a 32‐year‐old man with Hajdu‐Cheney syndrome (HJCYS), because of the de novo truncating mutation in the exon 34 of NOTCH2 (c.6424‐6427delTCTG, p.Ser2142ArgfsX4), who has been followed up for a period of 23 years (between 9 and 32 years). During follow‐up, we observed abnormalities of vision, hearing, voice, and progression of craniofacial features in the form of skeletal dysplasia with affected skull, dentition, spine, limbs, fingers, and toes. Low bone mineral density and history of fragility fractures also suggested primary osteoporosis being a clinical manifestation. According to Stengel‐Rutkowski, Schimanek, and Wernheimer (1984; Human Genetics, 6, 272–295), systematic data acquisition has been used for quantitative analysis of anthropological, radiographic, and clinical features at childhood, adolescence, and young adulthood separately. A detailed phenotype description together with the results of reanalysis of 14 reports so far published on patients with HJCYS and NOTCH2 mutation showed similar phenotype evolution with age. The spectrum of observed features may improve diagnostic tools for HJCYS at different periods of the lifespan.