Hunter syndrome (Muccopolysaccharridosis Type II) in Macedonia and Bulgaria.

BACKGROUND: Mucopolysaccharidosis II (MPS II) is caused by a deficiency of iduronate-2-sulfatase (IDS; EC 3.1.6.13). METHODS AND RESULTS: We describe 11 boys from Bulgaria and Macedonia detected in the period from 1998 to 2008. The mean age at diagnosis was 4.77+/-1.29 years. All children were severely retarded: IQ ranged from 34-80, and they all had coarse faces and hepatomegaly. In addition, splenomegaly was found in 81.81% patients, dysostosis in 45.45%, kyphosis in 27.27%, deafness in 18.08%, growth below the third percentile in 45.45%, growth below the parental target height in all patients, stiff joints in 56.56% and hypertrophic myocardiopathy in 18.18% children. Two patients died at the age of 11 and 35 years. Plasma iduronate-2-sulfatase was low in all probands and normal in parents and relatives. Two new mutations were discovered: p.K236N (c.708G>C) in a child with a moderately severe phenotype, and p.Q80K (c.238C>A) which resulted in a severe phenotype and early death at the age of 11 years. Heterozygote carriers of the pathogenic allele were 29 female relatives. The calculated incidence rate for MPS II in Macedonia (censuses 1994 and 2002, children under 14 years: 483,923 and 426,280) and Bulgaria (censuses 1992 and 2006, children under 14 years: 1 126, 598 and 1,077,020) are 0.36 and 0.46 respectively, while the calculated prevalence rate are 3.6 and 4.6 per 1,000,000 boys (aged 0-14 years). Correlating phenotype and genotype remains a complex endeavour. CONCLUSIONS: We report calculated incidence and prevalence rates in two South Eastern European countries, and 2 novel genetic alterations correlated with their phenotypes.

Type I Gaucher disease (GDI) in three siblings: enzyme replacement treatment (ERT) required.

(Full text is available at http://www.manu.edu.mk/prilozi). This is a family of three children, born to healthy Macedonian parents after uneventful pregnancies and delivery. The index child was an eight-year-old girl admitted for abdominal discomfort and distension: the spleen was 14cm below the costal margin (BCM), the liver 8cm BCM. No bone pain or pathology was reported. There was mild pancytopaenia (hemoglobin 11.2 gm/L; WBC counts 4.6 x 10;3; platelets 70 x 10;3). Liver function tests, renal ultrasound, bone scan, and a chest radiograph were within normal limits. Bone marrow analysis in this child and her two brothers (11 and 6.5 years old) revealed Gaucher cells. Both brothers had only mild anaemia, but the older brother had been splenectomized prior to diagnosis of GD1. Enzyme analysis revealed low activity (2.59, 1.62, and 2.55 nmol/h/mg protein, respectively); plasma chitotriosidase levels were also elevated. Genetic testing revealed homozygosity for the N370S/N370S mutation in all three siblings. In the absence of available enzyme replacement treatment (ERT), the girl was splenectomized. Removing an important immune organ (the spleen) introduces further risk for the patients. In addition, this does not solve the bone involvement characteristic for GD. ERT should be introduced for all GD1 patients in Macedonia. Key words: Gaucher disease, N370S mutation, siblings, enzyme replacement therapy.

Methods for a prompt and reliable laboratory diagnosis of Pompe disease: report from an international consensus meeting.

Pompe disease is an autosomal recessive disorder of glycogen metabolism caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). It presents at any age, with variable rates of progression ranging from a rapidly progressive course, often fatal by one-year of age, to a more slowly, but nevertheless relentlessly progressive course, resulting in significant morbidity and premature mortality. In infants, early initiation of enzyme replacement therapy is needed to gain the maximum therapeutic benefit, underscoring the need for early diagnosis. Several new methods for measuring GAA activity have been developed. The Pompe Disease Diagnostic Working Group met to review data generated using the new methods, and to establish a consensus regarding the application of the methods for the laboratory diagnosis of Pompe disease. Skin fibroblasts and muscle biopsy have traditionally been the samples of choice for measuring GAA activity. However, new methods using blood samples are rapidly becoming adopted because of their speed and convenience. Measuring GAA activity in blood samples should be performed under acidic conditions (pH 3.8-4.0), using up to 2 mM of the synthetic substrate 4-methylumbelliferyl-alpha-D-glucoside or glycogen (50 mg/mL), in the presence of acarbose (3-9 microM) to inhibit the isoenzyme maltase-glucoamylase. The activity of a reference enzyme should also be measured to confirm the quality of the sample. A second test should be done to support the diagnosis of Pompe disease until a program for external quality assurance and proficiency testing of the enzymatic diagnosis in blood is established.

Prenatal diagnosis of the Hunter syndrome and the introduction of a new fluorimetric enzyme assay.

Prenatal diagnosis of the Hunter syndrome (mucopolysaccharidosis type II; MPS II) is preferably achieved by the assay of iduronate-2-sulphate sulphatase (IDS) in uncultured chorionic villi (CV) as this allows early (12th week), rapid (2-3 days) and reliable results. We summarize the results of 174 prenatal analyses in the past 30 years, using various methods such as radiolabelled sulphate incorporation in amniotic fluid (AF) cells, glycosaminoglycan (GAG)-electrophoresis in AF and IDS assay in CV, CV-cells, AF and AF-cells. Twenty-seven fetuses with MPS II were diagnosed after finding clearly abnormal results in pregnancies with a male fetus; very low IDS activity has also been measured in some pregnancies with a (heterozygous) female fetus, emphasizing the need to combine enzyme assay with fetal sex determination. IDS activity has until recently been assessed by a cumbersome radioactive enzyme assay. Here we describe the use of a novel fluorigenic 4-methylumbelliferyl substrate, which allows a sensitive, rapid and convenient assay of IDS activity and reliable early prenatal diagnosis. This novel IDS assay was validated in retrospective analyses of 14 CV, CV-cell, AF and AF-cell samples from affected pregnancies in addition to prospective prenatal diagnosis in eight pregnancies at risk with one MPS II-affected fetus.