Mucopolysaccharidosis type VI in Russia, Kazakhstan, and Central and Eastern Europe.

BACKGROUND: The aim of this study was to describe the natural clinical course, incidence and prevalence of mucopolysaccharidosis type VI (MPS VI) in Russia, Kazakhstan, and Central and Eastern Europe. METHODS: Patients (n = 49) were identified by retrieving the data from eight international centers for MPS VI. RESULTS: A large number of patients presented with an attenuated phenotype (33%). Height and genotype were related to the severity of the disease, while no clear trend was observed between height and urinary glycosaminoglycan level. A high prevalence of the p.R152W mutation was observed both in the whole series (42%) as well as in Russian patients (43%). The incidence rate ranged from 0.0363 to 0.64 per 100,000 live births in Poland and Lithuania, respectively. CONCLUSIONS: The observed high p.R152W carrier frequency in the Lithuanian population may indicate a possible founder effect in this region. The high prevalence of this mutation observed in the whole series, as well as the Slavic origin of the majority of patients homozygous for this mutation, suggest that p.R152W may be of Slavic, not Lithuanian origin. Resettlement of the Polish population after World War II resulted in dilution of the prevalence of carriers in Poland and a very low MPS VI incidence.

Mucopolysaccharidosis type VI: a predominantly cardiac phenotype associated with homozygosity for p.R152W mutation in the ARSB gene.

Mucopolysaccharidosis type VI (MPS VI) is a rare lysosomal, autosomal recessive storage disorder caused by deficient activity of N-acetylgalactosamine-4-sulfatase (ARSB). Approximately, 140 ARSB gene mutations have been identified; however, most are private mutations making genotype-phenotype correlation for most MPS VI patients difficult. The aim of this study was to describe the natural clinical course in patients homozygous for the p.R152W mutation from eight unrelated families. From our database of 70 patients with MPS VI, we selected 10 patients homozygous for the p.R152W mutant allele (median age 27.5 years, range 18-38 years). We performed a cross-sectional observational study characterizing the onset and prevalence of clinical manifestations. First signs of the disease, such as cardiac valve disease, slightly decreased joint range of motion and mild growth retardation, were observed in mid-adolescent years (median 15 years). Within the disease course, the most common clinical feature in all the patients was progressive heart disease of predominantly valve origin leading to symptoms of heart failure. Other typical MPS VI features were subtle and not present in all the patients. Delays up to 23 years (median 8.5 years) intervened between symptom onset and disease diagnosis. Patients homozygous for the p.R152W mutation present a cardiac variant of MPS VI characterized by progressive cardiac valve disease leading to serious cardiac complications including abrupt death due to cardiac failure.

Human ring chromosomes and small supernumerary marker chromosomes-do they have telomeres?

Ring chromosomes and small supernumerary marker chromosomes (sSMC) are enigmatic types of derivative chromosomes, in which the telomeres are thought to play a crucial role in their formation and stabilization. Considering that there are only a few studies that evaluate the presence of telomeric sequences in ring chromosomes and on sSMC, here, we analyzed 14 ring chromosomes and 29 sSMC for the presence of telomeric sequences through fluorescence in situ hybridization (FISH). The results showed that ring chromosomes can actually fall into two groups: the ones with or without telomeres. Additionally, telomeric signals were detectable at both ends of centric and neocentric sSMC with inverted duplication shape, as well as in complex sSMC. Apart from that, generally both ring- and centric minute-shaped sSMC did not present telomeric sequences neither detectable by FISH nor by a second protein-directed immunohistochemical approach. However, the fact that telomeres are absent does not automatically mean that the sSMC has a ring shape, as often deduced in the previous literature. Overall, the results obtained by FISH studies directed against telomeres need to be checked carefully by other approaches.

Novel data on growth phenotype and causative genotypes in 29 patients with Morquio (Morquio-Brailsford) syndrome from Central-Eastern Europe.

Mucopolysaccharidosis type IVA, also known as Morquio (Morquio-Brailsford) syndrome results from accumulation of keratan sulfate (KS) and chondroitin-6-sulfate (C6S), whereas the primary cause is mutations in the gene encoding galactosamine (N-acetyl)-6-sulfatase (GALNS). Phenotypically it seems to be a well-defined condition, with two main clinical forms: mild (attenuated) and severe, which are determined based on a combination of symptoms, i.e., enzymatic activity of GALNS, age of onset, and symptom severity. Nevertheless, the natural history of MPSIVA in relation to specific anthropometric parameters (growth, head circumference, body proportions, and face phenotype) is not precisely characterized. The aim of our work was to analyze the aforementioned anthropometric parameters, including correlation to molecular data (causative GALNS mutations).

Heteromorphic variants of chromosome 9.

BACKGROUND: Heterochromatic variants of pericentromere of chromosome 9 are reported and discussed since decades concerning their detailed structure and clinical meaning. However, detailed studies are scarce. Thus, here we provide the largest ever done molecular cytogenetic research based on >300 chromosome 9 heteromorphism carriers. RESULTS: In this study, 334 carriers of heterochromatic variants of chromosome 9 were included, being 192 patients from Western Europe and the remainder from Easter-European origin. A 3-color-fluorescence in situ hybridization (FISH) probe-set directed against for 9p12 to 9q13~21.1 (9het-mix) and 8 different locus-specific probes were applied for their characterization. The 9het-mix enables the characterization of 21 of the yet known 24 chromosome 9 heteromorphic patterns. In this study, 17 different variants were detected including five yet unreported; the most frequent were pericentric inversions (49.4%) followed by 9qh-variants (23.9%), variants of 9ph (11.4%), cenh (8.2%), and dicentric- (3.8%) and duplication-variants (3.3%). For reasons of simplicity, a new short nomenclature for the yet reported 24 heteromorphic patterns of chromosome 9 is suggested. Six breakpoints involved in four of the 24 variants could be narrowed down using locus-specific probes. CONCLUSIONS: Based on this largest study ever done in carriers of chromosome 9 heteromorphisms, three of the 24 detailed variants were more frequently observed in Western than in Eastern Europe. Besides, there is no clear evidence that infertility is linked to any of the 24 chromosome 9 heteromorphic variants.

A new multicolor fluorescence in situ hybridization probe set directed against human heterochromatin: HCM-FISH.

A new multicolor fluorescence in situ hybridization (mFISH) probe set is presented, and its possible applications are highlighted in 25 clinical cases. The so-called heterochromatin-M-FISH (HCM-FISH) probe set enables a one-step characterization of the large heterochromatic regions within the human genome. HCM-FISH closes a gap in the now available mFISH probe sets, as those do not normally cover the acrocentric short arms; the large pericentric regions of chromosomes 1, 9, and 16; as well as the band Yq12. Still, these regions can be involved in different kinds of chromosomal rearrangements such as translocations, insertions, inversions, amplifications, and marker chromosome formations. Here, examples are given for all these kinds of chromosomal aberrations, detected as constitutional rearrangements in clinical cases. Application perspectives of the probe set in tumors as well as in evolutionary cytogenetic studies are given.

Paternally derived der(7)t(Y;7)(p11.1 approximately 11.2;p22.3)dn in a mosaic case with Turner syndrome.

An unusual mosaic karyotype was detected in a 6-year-old female patient with clinical diagnosis of Turner syndrome (TS). Cytogenetic and molecular cytogenetic studies revealed besides a cell line with 45,X a second cell line where the short arm of the Y-chromosome was translocated onto the short arm of a chromosome 7; karyotype: 45,X,der(7)t(Y;7)(p11.1 approximately 11.2;p22.3)/45,X. To delineate the mechanisms of rearrangement and karyotypic evolution in this case, further studies were performed. A maternal origin of the X-chromosome and biparental origin of both chromosomes 7 were determined by microsatellite analysis. Furthermore, using parental-origin-determination fluorescence in situ hybridization (pod-FISH) it could be established that the derivative chromosome 7 was of paternal origin. Overall, this is to the best of our knowledge the first report of such a complex mosaic TS karyotype.