A large
alkaptonuria (AKU) cohort was studied to better characterize the poorly understood
spondyloarthropathy of
rare disease AKU. Eighty-seven patients attended the National
Alkaptonuria Centre (NAC) between 2007 and 2020. Seven only attended once. Fifty-seven attended more than once and received
nitisinone 2 mg daily. Twenty-three attended at least twice without receiving
nitisinone. Assessments included questionnaire analysis, 18F Positron emission tomography computerised tomography (PETCT), as well as photographs of ochronotic pigment in eyes and ears at baseline when 2 mg
nitisinone was commenced and yearly thereafter. Blood and urine samples were collected for chemical measurement. The prevalence of
ochronosis, as well as
pain, PETCT and combined
pain and PETCT scores, was greatly increased at 90.5%, 85.7%, 100%, and 100%, respectively.
Joint pain scores were greatest in proximal joints in upper and lower limbs. PETCT joint scores were higher in proximal joints in upper limb but higher in distal joints in the lower limb. Spine
pain scores were highest in lumbar, followed by cervical, thoracic, and cervical regions at 77.4%, 59.5%, 46.4%, and 25%, respectively. PETCT spine scores were highest in thoracic followed by lumbar, cervical, and sacroiliac regions at 74.4%, 70.7%, 64.6%, and 47.8% respectively;
ochronosis associated closely with
spondyloarthropathy scores (R = .65; P < .0001).
Nitisinone reversed
ochronosis significantly, with a similar pattern of decreased joint and spine disease.
Spondyloarthropathy is a highly prevalent feature in this NAC cohort.
Ochronosis appears to be associated with
spondyloarthropathy.
Nitisinone decreases
ochronosis and had a similar nonsignificant effect pattern on
spondyloarthropathy.