Mutation spectrum and pivotal features for differential diagnosis of Mucopolysaccharidosis IVA patients with severe and attenuated phenotype.

Mucopolysaccharidosis IVA (MPS IVA) is a lysosomal storage disease caused by biallelic mutations in GALNS gene and characterized by progressive skeletal deformities with short stature. The aim of this study was to evaluate the genotype, longitudinal height measurement and clinical features of MPS IVA patients. Thirty-two patients from 22 families were enrolled. The ages of patients at diagnosis ranged from two months to 18 years of age, and followed up for three to twenty years. They were classified as severe and attenuated form (intermediate and mild) according to their height measurements. The mean height standard deviation scores (SDS) for Turkish standards at 0-3, 5 and 10 years of ages were found to be -1.1, -4.2 and -7.3 respectively in patients with severe phenotype, while they were +0.4, -1.5 and -3 for intermediate phenotype. Patients with severe form reached a mean final height of -8.5 SDS, and mild phenotype -3.6 SDS. The most common initial and current symptoms in the patients with the severe phenotype were pectus carinatus and/or kyphosis deformities which occurred between 5 months and 3 years of age, and genu valgum deformity which developed after 3 years of age. However, kyphoscoliosis was the most common initial and current findings in the attenuated phenotype. Although, initial symptoms appeared in early childhood in the intermediate phenotype, similar to the severe phenotype, the clinical findings progressed slowly and genu valgum deformity did not develop. In patients with mild phenotype, the onset of symptoms was after 5 years of age. In conclusion, this study provides significant insights into the initial and follow-up clinical features and height values that contribute to the differential diagnosis of the severe and intermediate phenotypes in early childhood. Eleven mutations in GALNS gene in which one of them is novel (c.416G>A) were associated with the severe phenotype and three mutations (c.1038C>A, c.850T>G, c.752G>A) lead to the attenuated phenotype.

Mucopolisacaridosis tipo IV como causa de talla baja patológica: reporte de un caso y revisión de la literatura / Mucopolysaccharidosis type IV as a cause of pathological short stature: a case report and literature review

Se presenta un caso clínico de síndrome de Morquio o mucopolisacaridosis tipo IV, en una niña de 5 años que consulta al servicio de endocrinología pediátrica del Hospital Pablo Tabón Uribe, por talla baja y deformidades esqueléticas que iniciaron al año de edad. Inicialmente admitida con una impresión diagnóstica de raquitismo, pero al evaluar el caso en conjunto con el grupo de ortopedia infantil se confirma el diagnóstico por clínica, hallazgos radiológicos característicos y pruebas específicas para mucopolisacaridosis. Se revisan los principales aspectos clínicos y radiológicos de la enfermedad y el manejo actual.

We report a case of Morquio syndrome, or mucopolysaccharidosis type IV, in a girl of 5 years attending the pediatric endocrinology service at the Pablo Tobón Uribe Hospital, because of short stature and skeletal deformities that began in the first year of life. Initially admitted with a working diagnosis of raquitism, but reassessment of the case by the children's orthopedic group confirmed the diagnosis by clinical, specific serological tests and characteristical radiological findings specific for mucopolysaccharidosis. We review the clinical and radiological characteristics of the disease and current treatment options.

N-acetylgalactosamine-6-sulfatase protein detection in MPS IVA patient and unaffected control samples.

BACKGROUND: Mucopolysaccharidosis type IVA (MPS IVA; Morquio syndrome) is a lysosomal storage disorder caused by a deficiency in the activity of the lysosomal hydrolase N-acetylgalactosamine-6-sulfatase (GALNS). MPS IVA patients can present with severe myelopathy, hearing loss, heart valve involvement, short trunk/dwarfism and corneal clouding. Early diagnosis of MPS IVA will allow potential treatments to be implemented before the onset of irreversible pathology. METHODS: We have developed a sensitive immune-quantification assay for the accurate detection of GALNS protein in skin fibroblasts, blood and plasma from unaffected control and MPS IVA patients. RESULTS: MPS IVA patient fibroblast extracts (n=11) had non-detectable (ND)-10 ng/mg of 6-sulfatase protein compared to 3-82 ng/mg for normal controls (n=19). Dried blood-spots from MPS IVA patients (n=4) contained ND-1.3 ng/L of 6-sulfatase protein compared to 18-145 ng/L for normal controls (n=49). Plasma from MPS IVA patients (n=7) contained ND 6-sulfatase protein compared to 1-9 ng/L for normal controls (n=49). CONCLUSIONS: The immune assay described here had the capacity to accurately measure the amount of GALNS protein in various biological samples, providing the basis of an assay that could be further developed to enable newborn and high-risk population screening for MPS IVA patients.

Dental findings in three siblings with Morquio's syndrome.

Three siblings with Morquo's syndrome are described. Cultured fibroblasts from the youngest sibling demonstrated a total absence of N-acethylgalactosamine-6-sulphate-sulphatase whereas beta-galactocidase activity was normal, thus verifying the diagnosis of MPS-IV A. Dental features such as pointed cusps, spade-shaped incisors, thin enamel and pitted buccal surfaces were observed in all three children. Furthermore, in all three siblings the TMJ was affected with severe resorption of the head of the condyle. Histological examination of exfoliated primary molars showed a band of increased porosity following the striae of Retzius in the outer part of the enamel. These developmental disturbances were occasionally associated with minor localized defects in the enamel surface. The importance of close monitoring of dental development and regular dental care in order to prevent attrition of the teeth, loss of vertical face height and subsequent risk of TMJ dysfunction is emphasized.

A novel common missense mutation G301C in the N-acetylgalactosamine-6-sulfate sulfatase gene in mucopolysaccharidosis IVA.

Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive lysosomal storage disorder caused by a genetic defect in N-acetylgalactosamine-6-sulfate sulfatase (GALNS). In previous studies, we have found two common mutations in Caucasians and Japanese, respectively. To characterize the mutational spectrum in various ethnic groups, mutations in the GALNS gene in Colombian MPS IVA patients were investigated, and genetic backgrounds were extensively analyzed to identify racial origin, based on mitochondrial DNA (mtDNA) lineages. Three novel missense mutations never identified previously in other populations and found in 16 out of 19 Colombian MPS IVA unrelated alleles account for 84.2% of the alleles in this study. The G301C and S162F mutations account for 68.4% and 10.5% of mutations, respectively, whereas the remaining F69V is limited to a single allele. The skewed prevalence of G301C in only Colombian patients and haplotype analysis by restriction fragment length polymorphisms in the GALNS gene suggest that G301C originated from a common ancestor. Investigation of the genetic background by means of mtDNA lineages indicate that all our patients are probably of native American descent.

Clinical findings in 12 patients with MPS IV A (Morquio's disease). Further evidence for heterogeneity. Part I: Clinical and biochemical findings.

Clinical heterogeneity in MPS IV A (Mucopolysaccharidosis IV A, Morquio Disease Type A)has become more clearly identified in recent years. The clinical findings in 12 cases of MPS IV A are described. Clinical presentation was variable, and some cases were only mildly affected. All showed deficiency of N-acetylgalactosamine-6-sulphate sulphatase in fibroblasts, but the patient with the mildest clinical presentation showed a high residual enzyme activity. The urinary glycosaminoglycans (GAGs) were examined on all patients by a two-dimensional electrophoresis technique which proved to be highly reliable and efficient. In particular, no false negative results were obtained, a problem often encountered with routine screening methods. These cases support the division of MPS IV A into three subgroups: the severe "classical" type, an intermediate type and a mild type, all caused by N-acetylgalactosamine-6-sulphate sulphatase deficiency. Residual enzyme activity may be an important prognostic indicator.

Clinical findings in 12 patients with MPS IV A (Morquio's disease). Further evidence for heterogeneity. Part II: Dental findings.

Typical dental changes were present in all cases, although they were of variable degree. However, the tooth morphology would appear to be highly specific for MPS IV A, and is not found in MPS IV B (beta-galactosidase deficiency) or the recently delineated MPS IV C (enzyme defect unknown). Thus the dental changes have a very useful diagnostic potential in mild atypical cases of MPS IV A, although they may only be demonstrable radiologically in some such cases.

Spondyloepiphyseal dysplasia tarda with progressive arthropathy.

We present a family with numerous first cousin marriages and several members affected with spondyloepiphyseal dysplasia tarda with progressive arthropathy causing severe crippling and deformity. The extensive pedigree provides strong evidence for autosomal recessive inheritance.

Spondylometepiphyseal dysplasia, Strudwick type.

The clinical and radiographic observations in eight patients, radiographs on an additional six patients, and morphologic observations on chondro-osseous tissue from two of these 14 patients form the basis for delineating an entity distinct from the heterogeneous group of skeletal dysplasia involving spine and tubular bones, the spondyloepiphyseal, and spondylometaphyseal dysplasias. Disproportionately short limbs and delayed epiphyseal maturation are present at birth, and the entity is radiographically indistinguishable from spondyloepiphyseal dysplasia (SED) congenita during infancy. The metaphyseal change that allows identification of the entity described here develops during early childhood, and radiographically is seen as "dappling," ie, the mottled appearance of alternating zones of osteosclerosis and osteopenia. Severe scoliosis and cord compression may be important clinical problems related to the spine changes in adulthood. We have identified one family with two affected sibs and normal parents, suggesting autosomal recessive inheritance and distinguishing the entity from SED congenita that has autosomal dominant inheritance.

[Pure spondylar dysplasia or brachyolmy. Apropos of a case]. / La dysplasie spondylaire pure ou brachyolmie. A propos d'une observation

A case of brachyolmy in a 13 year-old girl is reported. Growth retardation was detected when the child was 5 year old and became severe when 13 years. It concerned only the trunk, limbs being normal. Kyphoscoliosis, akromikia of hands and feet, slight facial dysmorphy with flat nose and thick lips were present. Characteristic radiological features were observed: kyphoscoliosis, platyspondyly with transversally enlarged and irregular vertebrae. Morphological changes of the other epiphyses were minimal: short and squat colla femorii and reduced size of the aleae ilii. Mental development was normal and polyvisceral examination unremarkable. No biological changes were demonstrable, mucopolysaccharides and urinary acids having been found normal. This condition may be transmitted as an autosomal recessive trait.