Patient-reported outcomes and functional assessments of patients with Alkaptonuria in a 3-year Nitisinone treatment trial.

Alkaptonuria is a rare disorder of tyrosine catabolism caused by deficiency of homogentisate 1,2-dioxygenase that leads to accumulation of homogentisic acid (HGA). Deposition of HGA-derived polymers in connective tissue causes progressive arthropathy of the spine and large joints, cardiac valvular disease, and genitourinary stones beginning in the fourth decade of life. Nitisinone, a potent inhibitor of the upstream enzyme, 4-hydroxyphenylpyruvate dioxygenase, dramatically reduces HGA production. As such, nitisinone is a proposed treatment for alkaptonuria. A randomized clinical trial of nitisinone in alkaptonuria confirmed the biochemical efficacy and tolerability of nitisinone for patients with alkaptonuria but the selected primary outcome did not demonstrate significant clinical benefit. Given that alkaptonuria is a rare disease with slow progression and variable presentation, identifying outcome parameters that can detect significant change during a time-limited clinical trial is challenging. To gain insight into patient-perceived improvements in quality of life and corresponding changes in physical function associated with nitisinone use, we conducted a post-hoc per protocol analysis of patient-reported outcomes and a functional assessment. Analysis revealed that nitisinone-treated patients showed significant improvements in complementary domains of the 36-Item Short-Form Survey (SF-36) and 6-min walk test (6MWT). Together, these findings suggest that nitisinone improves both quality of life and function of patients with alkaptonuria. The observed trends support nitisinone as a therapy for alkaptonuria.

Phenotype and course of Hutchinson-Gilford progeria syndrome.

BACKGROUND: Hutchinson-Gilford progeria syndrome is a rare, sporadic, autosomal dominant syndrome that involves premature aging, generally leading to death at approximately 13 years of age due to myocardial infarction or stroke. The genetic basis of most cases of this syndrome is a change from glycine GGC to glycine GGT in codon 608 of the lamin A (LMNA) gene, which activates a cryptic splice donor site to produce abnormal lamin A; this disrupts the nuclear membrane and alters transcription. METHODS: We enrolled 15 children between 1 and 17 years of age, representing nearly half of the world's known patients with Hutchinson-Gilford progeria syndrome, in a comprehensive clinical protocol between February 2005 and May 2006. RESULTS: Clinical investigations confirmed sclerotic skin, joint contractures, bone abnormalities, alopecia, and growth impairment in all 15 patients; cardiovascular and central nervous system sequelae were also documented. Previously unrecognized findings included prolonged prothrombin times, elevated platelet counts and serum phosphorus levels, measured reductions in joint range of motion, low-frequency conductive hearing loss, and functional oral deficits. Growth impairment was not related to inadequate nutrition, insulin unresponsiveness, or growth hormone deficiency. Growth hormone treatment in a few patients increased height growth by 10% and weight growth by 50%. Cardiovascular studies revealed diminishing vascular function with age, including elevated blood pressure, reduced vascular compliance, decreased ankle-brachial indexes, and adventitial thickening. CONCLUSIONS: Establishing the detailed phenotype of Hutchinson-Gilford progeria syndrome is important because advances in understanding this syndrome may offer insight into normal aging. Abnormal lamin A (progerin) appears to accumulate with aging in normal cells. (ClinicalTrials.gov number, NCT00094393.)

A 3-year randomized therapeutic trial of nitisinone in alkaptonuria.

Alkaptonuria is a rare, autosomal recessive disorder of tyrosine degradation due to deficiency of the third enzyme in the catabolic pathway. As a result, homogentisic acid (HGA) accumulates and is excreted in gram quantities in the urine, which turns dark upon alkalization. The first symptoms, occurring in early adulthood, involve a painful, progressively debilitating arthritis of the spine and large joints. Cardiac valvular disease and renal and prostate stones occur later. Previously suggested therapies have failed to show benefit, and management remains symptomatic. Nitisinone, a potent inhibitor of the second enzyme in the tyrosine catabolic pathway, is considered a potential therapy; proof-of-principle studies showed 95% reduction in urinary HGA. Based on those findings, a prospective, randomized clinical trial was initiated in 2005 to evaluate 40 patients over a 36-month period. The primary outcome parameter was hip total range of motion with measures of musculoskeletal function serving as secondary parameters. Biochemically, this study consistently demonstrated 95% reduction of HGA in urine and plasma over the course of 3 years. Clinically, primary and secondary parameters did not prove benefit from the medication. Side effects were infrequent. This trial illustrates the remarkable tolerability of nitisinone, its biochemical efficacy, and the need to investigate its use in younger individuals prior to development of debilitating arthritis.

Natural history of alkaptonuria.

BACKGROUND: Alkaptonuria, caused by mutations in the HGO gene and a deficiency of homogentisate 1,2-dioxygenase, results in an accumulation of homogentisic acid (HGA), ochronosis, and destruction of connective tissue. There is no effective therapy for this disorder, although nitisinone inhibits the enzyme that produces HGA. We performed a study to delineate the natural history of alkaptonuria. METHODS: We evaluated 58 patients with alkaptonuria (age range, 4 to 80 years), using clinical, radiographic, biochemical, and molecular methods. A radiographic scoring system was devised to assess the severity of spinal and joint damage. Two patients were treated with nitisinone for 10 and 9 days, respectively. RESULTS: Life-table analyses showed that joint replacement was performed at a mean age of 55 years and that renal stones developed at 64 years, cardiac-valve involvement at 54 years, and coronary-artery calcification at 59 years. Linear regression analysis indicated that the radiographic score for the severity of disease began increasing after the age of 30 years, with a more rapid increase in men than in women. Twenty-three new HGO mutations were identified. In a 51-year-old woman, urinary HGA excretion fell from 2.9 to 0.13 g per day after a 10-day course of nitisinone (7 days at a dose of 0.7 mg per day and 3 days at 2.8 mg per day). In a 59-year-old woman, urinary HGA fell from 6.4 g to 1.7 g per day after nine days of treatment with nitisinone (0.7 mg per day). Plasma tyrosine levels in these patients rose from approximately 1.1 mg per deciliter (60 micromol per liter) in both to approximately 12.8 mg per deciliter (700 micromol per liter) and 23.6 mg per deciliter (1300 micromol per liter), respectively, with no clinical signs or symptoms. CONCLUSIONS: The reported data on the natural history of alkaptonuria provide a basis for the evaluation of long-term therapies. Although nitisinone can reduce HGA production in humans with homogentisate 1,2-dioxygenase deficiency, the long-term safety and efficacy of this treatment require further evaluation.

Use of nitisinone in patients with alkaptonuria.

Alkaptonuria, a rare autosomal recessive disorder caused by mutations in the HGD gene and deficiency of homogentisate 1,2 dioxygenase, is characterized by ochronosis, arthritis, and daily excretion of gram quantities of homogentisic acid (HGA). Nitisinone, an inhibitor of the enzyme 4-hydroxyphenylpyruvate dioxygenase, can drastically reduce urinary excretion of HGA in individuals with alkaptonuria. We investigated the safety and the HGA-depleting efficacy of nitisinone in an open-label, single-center study of 9 alkaptonuria patients (5 women, 4 men; 35-69 years of age) over the course of 3 to 4 months. Each patient received nitisinone in incremental doses, 0.35 mg bid followed by 1.05 mg bid, and remained on this dosage and a regular diet for 3 months. Nitisinone reduced urinary HGA levels from an average of 4.0 +/- 1.8 (SD) g/day to 0.2 +/- 0.2 g/day ( P < .001). The average plasma tyrosine concentration, initially 68 +/- 18 mmicro mol/L, rose to 760 +/- 181 micro mol/L ( P < .001). During the final week of the study, 5 patients adhered to a protein-restricted diet (40 g/day), and their mean plasma tyrosine level fell from 755 +/- 167 to 603 +/- 114 mu mol/L. Six of the 7 patients who received nitisinone for more than 1 week reported decreased pain in their affected joints. Weekly ophthalmologic examinations showed no signs of corneal toxicity. Adverse events included the passing of kidney stones, the recognition of symptoms related to aortic stenosis, and elevation of liver transaminase levels. We conclude that low-dose nitisinone effectively reduced urinary HGA levels in patients with alkaptonuria. Future long-term clinical trials are planned to determine the benefits of nitisinone in preventing joint deterioration and providing pain relief, and its long-term side effects.

Digital stereophotogrammetry as a new technique to quantify truncal deformity: a pilot study in persons with osteogenesis imperfecta.

The objective of this pilot study was to determine the usability of stereophotogrammetry (SP) as a noninvasive technique for obtaining linear measures and anatomical data of the torso in people with osteogenesis imperfecta in comparison with clinical observations. Ten participants were recruited from subjects enrolled in ongoing institutional review board-approved osteogenesis imperfecta protocols at the National Institute of Child Health and Human Development. Using a Gulick tape measure, anthropometer, and the SP system proprietary software, linear measurements of the torso were taken. In addition, the presence or absence of specific torso deformities was documented from both clinical observation and evaluation of SP images. Measurements of torso diameter and circumference by SP demonstrated strong agreement with the manual measurements (intraclass correlation coefficient = 0.995 and 0.964, respectively). Substantial and statistically significant agreement was present between SP image evaluation and clinical observation for pectus carinatum (κ = 0.52 ± 0.23) and thoracic scoliosis (κ = 0.72 ± 0.12). The kappa values between clinical observation and SP evaluations of other torso deformities were not significant. The strong correlations and P values determined by this study demonstrate the potential value of SP in studying persons with truncal deformities. However, the weak agreement between SP and some clinical observations suggests that further development of SP image analysis tools is required before SP can be used as a standard method of diagnosis or assessment of treatment success.

Musculoskeletal findings and disability in alkaptonuria.

OBJECTIVE: To describe the musculoskeletal (MSK) findings in patients with alkaptonuria and to show which of these factors are associated with disability in this population. METHODS: This is a prospective cross-sectional MSK assessment of subjects. Participants included 53 patients with alkaptonuria across the life span, 22 female and 31 male, mean age 43.6 years (10-80 yrs), participating in a natural history study supported by the National Human Genome Research Institute (NHGRI). Assessments included objective measures of the MSK system (range of motion, radiographic assessment of joints and spine, etc.) and questionnaires including the Human Activity Profile (HAP), Health Assessment Questionnaire (HAQ), SF-36 health survey, and the Fatigue Assessment Instrument. RESULTS: There were 18 patients with kyphosis, 16 with scoliosis, 16 with marked reduction in range of motion of at least one major joint, 15 with joint replacements of major joints, 11 with tendon ruptures. A positive Schober's test was highly correlated with substantial functional loss and associated with disability as measured by the HAP (p < or = 0.0001), HAQ (p < or = 0.0001), and the physical component summary (p < or = 0.0001) of the SF-36 health survey. Severity of lumbar spine involvement had the greatest correlation with disability measures (p < or = 0.0001). All objective and subjective physical measures worsened with age. CONCLUSION: Disability is common and severe in patients with alkaptonuria and correlates well with physical findings. Disability does not correlate with self-reports of mental competencies. Aging with alkaptonuria is associated with progressive disability.

Ultrasound, magnetic resonance imaging, and posterior tibialis dysfunction.

The authors studied posterior tibialis tendons in 31 subjects with posterior tibialis tendon pain to compare clinical findings with those of magnetic resonance imaging and ultrasound images. All subjects received clinical, ultrasound, and magnetic resonance imaging examinations using T1-weighted, T2-weighted, and enhanced magnetic resonance imaging, and high resolution ultrasound using power Doppler. Forty-four tendons in 25 women and six men with a mean age 43.3 years (range, 20-73 years) were studied. Magnetic resonance imaging tendon and peritendon enhancement are associated statistically with increasing pain intensity on resistance to testing. Ultrasound tendon and peritendon flow were associated with increasing pain intensity on resistance to testing. There is no statistically significant association between magnetic resonance imaging inhomogeneity and pain intensity on resistance to testing. Clinical and ultrasound examinations positively identify peritendinitis and tendonitis but not inhomogeneity (partial tear) of the posterior tibialis tendon. The magnetic resonance imaging is a more sensitive test for posterior tibialis tendon tear than either clinical or ultrasound evaluation.

Sonography and MR imaging of posterior tibial tendinopathy.

OBJECTIVE: The purpose of the study is to describe the appearance of the posterior tibialis tendon on MR imaging and high-resolution sonography with color and power Doppler imaging and to determine whether sonography is as accurate for diagnosing tendinosis as MR imaging. SUBJECTS AND METHODS: Fifteen healthy volunteers and 31 patients (44 tendons) who were clinically suspected of having posterior tibial tendinopathy were prospectively evaluated with MR imaging and sonography. RESULTS: On MR imaging, the normal tendon was elliptic on cross section and showed low signal intensity on all sequences. Minimal peritendinous enhancement and fluid were seen. On sonography, the tendon showed homogeneous longitudinal echogenic fibers. No flow was seen in or around the tendon. Tendinopathy was characterized by enhancement of the tendon on MR imaging (19/44 tendons); intratendinous flow on color Doppler sonography (16/44 tendons); increase in the anteroposterior diameter causing a rounding of the tendon (18/44 tendons); and inhomogeneity of the tendon (16/44 tendons on MR imaging and 21/44 tendons on sonography). Peritendinosis was characterized by peritendinous enhancement on MR imaging (29/44 tendons); flow on color Doppler sonography (20/44 tendons); and increased soft tissue (20/44 tendons on MR imaging and 27/44 tendons on sonography). When compared with MR imaging, the sensitivity and specificity of sonography for diagnosing tendinopathy were 80% and 90%, respectively, and for diagnosing peritendinosis were 90% and 80%. Addition of abnormal size to the structural abnormality criteria did not improve diagnostic ability. CONCLUSION: Sonography can be useful as the initial imaging study in evaluating abnormalities caused by posterior tibial tendinopathy.