A systematic review of the prevalence of Morquio A syndrome: challenges for study reporting in rare diseases

Abstract

BackgroundMorquio A (MPS IVA) is a rare disease characterised by a deficiency of N-acetylgalactosamine-6 sulfatase (GALNS) and presenting with short stature, abnormal gait, cervical spine instability and shortened lifespan.PurposeTo prepare a systematic review of the prevalence of Morquio A in multiple countries and suggest recommendations for reporting rare diseases.MethodsMedline, Medline In-Process, Medline Daily Update, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database and PROSPERO were searched from inception to October 2013 to identify relevant information on the epidemiology of Morquio A. Forty Patient Organisation Representatives (POR) and Key Opinion Leaders (KOL) across 24 countries were contacted for data. Observational studies were included and case reports were excluded. Searches were performed without date or language restriction. Two researchers independently screened and extracted data. Quality of study reporting was assessed using a checklist adapted from STROBE (STrengthening the Reporting of OBservational studies in Epidemiology). Point or birth prevalence was stratified according to diagnostic method and discussed narratively.ResultsIn total 9,074 records were retrieved from searching and 25 studies were included for data extraction. Twenty out of 40 KOL and POR responded (50%) and 9 provided data (23%). Point prevalence of Morquio A was 1 per 926,000 in Australia, 1 per 1,872,000 in Malaysia and 1 per 599,000 in UK and Morquio (unclassified) was 1 per 323, 000 in Denmark. Birth prevalence of Morquio A (using recommended diagnostic methods) ranged from 1 per 71,000 in UAE to 1 per 500,000 in Japan. All results were compromised by poor study reporting and internal validity.ConclusionsThe review highlighted that there is a misunderstanding of the definitions for prevalence and incidence in the field; that studies were poorly reported (diagnostic methods and patient characteristics) and that no suitable quality assessment tool exists. Overestimation and underestimation of prevalence data can occur. Bespoke reporting guidelines and a quality assessment tool specifically for prevalence of rare diseases are recommended.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-014-0173-x) contains supplementary material, which is available to authorized users.

Social/economic costs and health-related quality of life of mucopolysaccharidosis patients and their caregivers in Europe

“…However, prevalence data on MPS varies substantially across Europe and diagnostic methods and patient characteristics are often poorly reported [7]. According to a review by Jurecka et al, the prevalence of MPS (all types) per 100,000 live births was 4.50 in the Netherlands, 3.72 in the Czech Republic, 3.53 in Germany, 3.08 in Norway, 1.77 in Denmark, 1.75 in Sweden, and 1.81 in Poland [8].…”

Elosulfase alfa (BMN 110) for the treatment of mucopolysaccharidosis IVA (Morquio A Syndrome)

“…The point prevalence of Morquio A syndrome has been reported as 1 per 323,000 (Denmark), 1 per 599,000 (United Kingdom), 1 per 926,000 (Australia), and 1 per 1,872,000 (Malaysia) [7]. The birth prevalence of Morquio A using the recommended diagnostic methods ranges from 1 per 71,000 in the United Arab Emirates to 1 per 500,000 in Japan.…”

Enfermedad de Morquio (mucopolisacaridosis IV-A): aspectos clínicos, diagnósticos y nuevo tratamiento con terapia de reemplazo enzimático

“…2 Los síntomas de inicio característicos que se reportan con mayor frecuencia incluyen deformidad ósea, baja talla y alteraciones de la marcha. La edad de inicio en más del 50% de los pacientes con formas graves es de 2,2 años, aunque el diagnóstico suele retrasarse por, al menos, 3 años, lo que lleva a una media de edad para el diagnóstico de 4,9 años.…”

“…Si bien hay diferencias en la presentación clínica, se han descrito radiológicamente los siguientes hallazgos: silla turca en forma de J, aumento del espacio diploico en la calota, clavículas cortas y gruesas, cuerpo vertebral en pico y borde posterior festoneado (Figura 1), alas ilíacas redondeadas, coxa valga (Figura 2), epífisis hipoplásicas (predominantemente, a nivel distal de cúbito y radio) (Figura 3), engrosamiento y acortamiento diafisario, retraso de la edad ósea con respecto a la edad cronológica en los huesos de la mano (disociación carpo-epifisaria) y osificación tardía o no presente del escafoides (Figura 4). [1][2][3] El análisis de la frecuencia de los distintos componentes de la DM sobre la base del registro Morquio muestra en orden decreciente genu valgo, giba lumbar (Figura 1), pectumcarinatum, deformidades en las muñecas, la cadera, el fémur y el tobillo. 7 Posiblemente, otra manifestación característica y que solo se evidencia en la MPS IV-A es la hiperlaxitud articular (Figura 4).…”

“…S u incidencia en la población general es de 1/200 000, aunque se han reportado desde 1/76 000 nacidos vivos en el norte de Irlanda hasta 1/640 000 en el oeste de Australia. 2 La MPS IV-A es el resultado de mutaciones en el gen que codifica para la enzima lisosomal N-acetylgalactosamina-6 -s u l f a t o s u l f a t a s a ( G A L N S ) , lo que deriva en una reducción o ausencia del catabolismo de dos glicosaminoglicanos: el condroitín sulfato y el queratán sulfato. 3 Como en las otras MPS, existen distintas formas de presentación, que varían desde una forma grave (también llamada clásica) hasta una forma leve (o llamada atenuada).…”