Prenatal diagnosis of morquio disease type A using a simple fluorometric enzyme assay

A new fluorogenic substrate, 4 methylumbelliferyl B-D-6-sulphogalactoside, was used for the assay of galactose-6-sulphate sulphatase activity in chorionic villi, cultured villus cells, and amniocytes. The fluorometric assay is much more convenient than the conventional assay using radiolabelled, sulphated oligosaccharides. Both types of substrate were used in the prenatal diagnosis of three pregnancies at risk for Morquio type A disease using amniocytes. These enzyme tests, as well as electrophoresis of glycosaminoglycans in the amniotic fluid, indicated affected fetuses in two pregnancies and a non-affected fetus in one

Indentification of three different chromosomal additions by chromosome painting using fluorescence in situ hybridization [FISH] technique

Fluorescence in situ hybridization (FISH) is a very useful method for assessing chromosome rearrangements. When neither banding pattern nor clinical symptoms are sufficient to determine the origin of additional chromosomal fragment, FISH with multiple chromosome-specific libraries (chromosome painting), allows to solve this diagnostic problem rapidly. Three chromosomal additions, 7q+, 13p+ and 22q+, found in routine cytogenetic studies performed in children with phenotypic abnormalities were analysed using FISH. This technique documented the origin of the extra material to be derived from chromosome 16[der(7)t(7; 16)(q36.3;p 13.11)], 18[der(13)t(13; 18)(p12;q 12.2)] and 22[dup(22)(q11.2q13.1)], respectively. In two cases the abnormality arose de novo, while in the third case the product of translocation t(13;18) was maternal by origin. It was present in 30% of mother's lymphocytes, and in 70% of them a balanced Robertsonian translocation t(13q;15q) was found. In the presented cases the chromosome analysis with both traditional banding and chromosome painting techniques, allowed to establish final clinical diagnosis

Relationship between molecular, cytogenetic and clinical parameters in 63 individuals with full mutation in FMR1 gene

Relationship between selected molecular, cytogenetic and clinical parameters was analysed in a group of 63 individuals (45 males and 18 females) with full fragile X mutation. Significant correlation between the size and somatic instability of fully mutated alleles in both males and females was found. Possible explanations of this result are discussed. With respect to the mutation size, an apparent difference was observed between males with different degree of mental retardation. No such difference appeared when affected and normal females with full mutation were compared. The proportion of mutated active X chromosome was significantly higher in mentally retarded females than in those without any mental impairment

Supernumerary marker chromosomes characterized by fluorescence in situ hybridization [FISH]

Until recently marker chromosomes have presented a difficult diagnostic problem for cytogeneticists as well as for clinicians. Introduction of FISH to cytogenetic analysis has enabled identification of their origin giving possibility to outline specific phenotypic effects of defined marker chromosomes. Nine marker chromosomes were analysed with FISH using centromeric probes, chromosome- specific libraries and unique DNA sequences probes for PWS/AS critical region. The origin from acrocentric chromosomes was established in 6 cases. One marker was a product of maternal 11;22 translocation and two others were pericentromeric regions of chromosome 2 and 4. Among 6 markers, derived from acrocentric chromosomes, 2 consisted of pericentromeric part of chromosome 15, one was identified as mar (21) and in 3 other cases the origin could not be differentiated between chromosomes 13 and 21 or 14 and 22. Clinical consequences of marker chromosomes including the risk for chromosomal nondisjunction and trisomy 21 as well as the risk for uniparental disomy (UPD) are discussed

Different haplotypes for cystic fibrosis-linked DNA polymorphisms in Polish and Dutch populations

We analyzed DNA from 34 Polish and 63 Dutch cystic fibrosis (CF) patients and their families using the polymorphic markers XV2c and KM19, which are in linkage disequilibrium with the CF mutation. Strong linkage disequilibrium was found in the Dutch population sample, but the haplotypes of the Polish chromosomes showed a significantly less extreme disequilibrium. Our data and previous studies indicate that the highest degree of homogeneity of the CF defect and hence the best possible use of the XV2c/KM19/CF linkage disequilibrium for CF carrier detection/exclusion is in populations of northern European origi

Molecular versus classical cytogenetics - evaluation of 20 Prader-Willi syndrome patients

Prader-Willi syndrome (PWS) is a developmental disorder caused by a deficiency of paternal contribution of the chromosome region 15q11.2-q13 arising from differently sized deletions, maternal disomy, or rarely imprinting mutations. We have analyzed 20 PWS patients using combined cytogenetic high resolution technique (HRT), fluorescence in situ hybridization (FISH) and molecular studies to identify parental origin (uniparental disomy) or molecular defect (deletion) of the Prader-Willi region. Lack of a paternal copy of 15q11.2-q13 resulting from its deletion was found in 16 patients. Using high resolution GTG banding on prometaphase chromosomes, deletion in the 15q11.2-q13 region was detected in only 8 patients. Application of FISH with different sets of PWS specific unique sequence probes (D15S11, SNRPN, D15S10, GABRß3) revealed microdeletions in 12 patients. In 12 out of 20 cases FISH confirmed HRT studies, while in 8 cases inconsistent results were obtained. No discrepancies between results of FISH and molecular studies were found, although the latter had a higher sensitivity. We conclude that FISH appears to be a rapid and reliable method of microdeletion identification and should be performed as a method of choice in cytogenetic diagnosis of Prader-Willi syndrome

Identification of supernumerary marker chromosomes derived from chromosomes 5, 6, 19, and 20 using FISH

A large number of cases with supernumerary marker chromosomes (SMCs) should be compared to achieve a better delineation of karyotype-phenotype correlations. Here we present four phenotypically abnormal patients with autosomal marker chromosomes analysed by fluorescence in situ hybridisation using centromeric, telomeric, and unique sequence probes, as well as forward and reverse painting. We also report the first case, to the best of our knowledge, of an SMC derived from chromosome 5. Furthermore, a marker chromosome 20 in a patient with sex differentiation abnormalities, a double mar(6) in a boy with psychomotor retardation, and the association of r(19) with dup(21q21.2q22.12) are described. Although the mar(6) was very small, the presence of euchromatin was shown, suggesting that the partial trisomy of pericentric region derived sequences is implicated in the aetiology of the abnormal phenotypes.


Keywords: supernumerary marker chromosomes; fluorescence in situ hybridisation; phenotype-genotype correlatio