In humans, HMX3 and HMX2 are located together, close to FGFR4, on chromosome 10; hemizygous microdeletions that remove all three genes are thought to be causative for syndromes characterised by inner ear morphological anomalies, vestibular dysfunction and sensorineural hearing loss [48, 49]. The gene discussed is FGFR4; the disease is sensorineural hearing loss disorder.