Epidemiological and clinical characteristics of symptomatic hereditary transthyretin amyloid polyneuropathy: a global case series.

We describe 542 cases of symptomatic hereditary transthyretin amyloid polyneuropathy (ATTR-PN) identified through a review of the literature published between 2005 and 2016. Approximately 18% of the cases were from countries where ATTR-PN is traditionally considered to be endemic (i.e., Portugal, Japan, and Sweden). East Asia (Japan, China, Taiwan, and South Korea) contributed a sizeable combined proportion (37.0%, n = 200) with Japan (n = 92) and China (n = 71) being the primary contributors. The most common genotypes among the 65 genotypes represented in the sample were Val30Met (47.6%), Ser77Tyr (10%), Ala97Ser (6.5%), and Phe64Leu (4.4%). Cases with genotypes other than the aforementioned four had the lowest ages at onset (mean 49.2 [standard deviation {SD} 21.0; inter-quartile range {IQR}14.7]) and diagnosis (mean 53.4 [SD 21.0; IQR 14.7]). Conversely, Phe64Leu mean age of onset was 67.5 (SD 8.8; IQR 5.2) and mean age of diagnosis was 71.3 (SD 8.8; IQR 5.4). The prevalence of upper and lower limb involvement at the time of diagnosis (67 and 41%) observed across all cases is consistent with the typical presentation of ATTR-PN. Other notable findings at the time of diagnosis included a high rate of impotence among the Ala97Ser cases versus all others (67% vs. 21%) and a high rate of non-motor visual symptoms (i.e., visual opacities and glaucoma) in the Ser77Tyr cases versus all others (93% vs. 16%). Though comparisons were made descriptively and were hindered by inconsistency of reporting across the cases, these findings support the notion that ATTR-PN is a more phenotypically and geographically variable disease than is typically considered.

Estimating the global prevalence of transthyretin familial amyloid polyneuropathy.

INTRODUCTION: This study sought to estimate the global prevalence of transthyretin familial amyloid polyneuropathy (ATTR-FAP). METHODS: Prevalence estimates and information supporting prevalence calculations was extracted from records yielded by reference-database searches (2005-2016), conference proceedings, and nonpeer reviewed sources. Prevalence was calculated as prevalence rate multiplied by general population size, then extrapolated to countries without prevalence estimates but with reported cases. RESULTS: Searches returned 3,006 records; 1,001 were fully assessed and 10 retained, yielding prevalence for 10 "core" countries, then extrapolated to 32 additional countries. ATTR-FAP prevalence in core countries, extrapolated countries, and globally was 3,762 (range 3639-3884), 6424 (range, 1,887-34,584), and 10,186 (range, 5,526-38,468) persons, respectively. DISCUSSION: The mid global prevalence estimate (10,186) approximates the maximum commonly accepted estimate (5,000-10,000). The upper limit (38,468) implies potentially higher prevalence. These estimates should be interpreted carefully because contributing evidence was heterogeneous and carried an overall moderate risk of bias. This highlights the requirement for increasing rare-disease epidemiological assessment and clinician awareness. Muscle Nerve 57: 829-837, 2018.

Early treatment with laronidase improves clinical outcomes in patients with attenuated MPS I: a retrospective case series analysis of nine sibships.

BACKGROUND: Enzyme replacement therapy (ERT) with laronidase, (recombinant human α-L-iduronidase; Aldurazyme) is the primary treatment option for patients with attenuated mucopolysaccharidosis type I (MPS I). This study examined the effect of early ERT on clinical manifestations. METHODS: This multinational, retrospective case series abstracted data from records of 20 patients with Hurler-Scheie syndrome within nine sibships that included older siblings treated with laronidase after the development of significant clinical symptoms, and younger siblings treated before significant symptomatology. Median age at diagnosis was 5.6 and 0.5 years for older and younger siblings, respectively. Median age at ERT initiation was 7.9 and 1.9 years for older and younger siblings, respectively. RESULTS: Improvement or stabilization of somatic signs and symptoms was more notable in younger siblings. Organomegaly present at onset of ERT improved in the majority of both older and younger siblings. Analysis of physician-rated symptom severity demonstrated that cardiac, musculoskeletal, and cognitive symptoms, when absent or mild in younger siblings at ERT initiation, generally did not develop or progress. The majority of older siblings had height/length Z-scores greater than two standard deviations below the mean (less than -2) at both time points. In general, Z-scores for younger siblings were closer to the sex- and age-matched means at follow-up. CONCLUSIONS: These findings suggest early initiation of laronidase, prior to the onset of symptoms in patients with attenuated MPS I, can slow or prevent the development of severe clinical manifestations.

Airway-related symptoms and surgeries in patients with mucopolysaccharidosis I.

OBJECTIVE: Mucopolysaccharidosis I (MPS I) is a progressive, debilitating, and life-threatening genetic disease, which, owing to the nonspecific nature of the early symptoms, is often unrecognized and associated with significant diagnostic delays. To improve early recognition leading to early diagnosis and initiation of treatment, we characterized the extent of airway-related symptoms and surgeries among patients with MPS I. METHODS: Analysis of the frequency of airway-related symptoms and surgeries from 1041 patients enrolled in the MPS I Registry and correlation with other systemic manifestations of MPS I. RESULTS: Airway-related symptoms (macroglossia, enlarged tonsils, reactive airway disease/asthma, or sleep disturbances) were reported for as many as 85% of Hurler, 83% of Hurler-Scheie, and 65% of Scheie patients-very often before the diagnosis of MPS I was established. Surgeries for an airway indication were reported in 39% of patients and many had at least 1 airway-related surgery before the diagnosis of MPS I was confirmed. The mean percentage of patients with airway-related symptoms for whom hernias and/or dysostosis multiplex were also reported was 84% and 54%, respectively. CONCLUSION: Airway-related symptoms and surgeries are common and often the earliest presenting feature in MPS I. Improved recognition of early MPS I disease manifestations may lead to earlier diagnosis and treatment.

The natural history of MPS I: global perspectives from the MPS I Registry.

PURPOSE: In this study, we aimed to describe the natural history of mucopolysaccharidosis I. METHODS: Data from 1,046 patients who enrolled in the MPS I Registry as of August 2013 were available for descriptive analysis. Only data from untreated patients and data prior to treatment for patients who received treatment were considered. Age at symptom onset, diagnosis, and treatment initiation were examined by geographic region and phenotype (from most to least severe: Hurler, Hurler-Scheie, and Scheie). For each symptom, frequency and age at onset were examined. RESULTS: Natural history data were available for 987 patients. Most patients were from Europe (45.5%), followed by North America (34.8%), Latin America (17.3%), and Asia Pacific (2.4%). Phenotype distribution was 60.9% for Hurler, 23.0% for Hurler-Scheie, and 12.9% for Scheie (3.2% undetermined) syndromes. Median age at symptom onset for Hurler, Hurler-Scheie, and Scheie syndromes was 6 months, 1.5 years, and 5.3 years, respectively; median age at treatment initiation was 1.5 years, 8.0 years, and 16.9 years, respectively. Coarse facial features and corneal clouding were among the most common symptoms in all three phenotypes. CONCLUSION: A delay between symptom onset and treatment exists, especially in patients with attenuated mucopolysaccharidosis I. A better understanding of disease manifestations may help facilitate prompt diagnosis and treatment and improve patient outcomes.