Unusual chromatographic behavior of oligonucleotide sequence isomers on two different anion exchange HPLC columns.

The retention behavior of the unmodified phosphodiester oligonucleotide sequence isomers was investigated on two different anion exchange columns: Biospher GMB 1000Q (based on DEAE-modified glycidyl methacrylate) and PolyWAX LP (based on silica with a crosslinked coating of linear polyethyleneimine). There was a notable difference in retention of oligonucleotides of the same composition but differing in the position of a single base. The most pronounced difference was observed between the oligonucleotides with the variable base in the end and in the center of the sequence. The use of either acetonitrile or 2-propanol as a mobile phase organic modifier did not markedly affect the retention time patterns. Prediction of the retention times of oligonucleotides must take into account the base position as well as identity. This is the first report of such a "same composition different sequence" effect, described for the short peptides, for synthetic oligonucleotides.

Familial hypertrophic cardiomyopathy owing to double heterozygosity for a 403Arg--> Trp mutation in exon 13 of the MYH7 gene and a novel mutation, 453Arg--> His, in exon 14 of the MYH7 gene: A case report.

An unusual clinical history of a 23-year-old male proband with obstructive hypertrophic cardiomyopathy associated with a rare genotype is presented. Genetic analysis of the proband found evidence for two distinct mutations of the MYH7 gene (the gene coding for the beta-myosin heavy chain): 403Arg--> Trp in exon 13 and a novel mutation, 453Arg--> His, in exon 14. A heterozygous site mutation was identified in exon 13 in the proband's father but no mutation site was found in his mother. Thus, the novel mutation in exon 14 is a de novo mutation.

A somatic origin of homologous Robertsonian translocations and isochromosomes.

One t(14q14q), three t(15q15q), two t(21q21q), and two t(22q22q) nonmosaic, apparently balanced, de novo Robertsonian translocation cases were investigated with polymorphic markers to establish the origin of the translocated chromosomes. Four cases had results indicative of an isochromosome: one t(14q14q) case with mild mental retardation and maternal uniparental disomy (UPD) for chromosome 14, one t(15q15q) case with the Prader-Willi syndrome and UPD(15), a phenotypically normal carrier of t(22q22q) with maternal UPD(22), and a phenotypically normal t(21q21q) case of paternal UPD(21). All UPD cases showed complete homozygosity throughout the involved chromosome, which is supportive of a postmeiotic origin. In the remaining four cases, maternal and paternal inheritance of the involved chromosome was found, which unambiguously implies a somatic origin. One t(15q15q) female had a child with a ring chromosome 15, which was also of probable postmeiotic origin as recombination between grandparental haplotypes had occurred prior to ring formation. UPD might be expected to result from de novo Robertsonian translocations of meiotic origin; however, all de novo homologous translocation cases, so far reported, with UPD of chromosomes 14, 15, 21, or 22 have been isochromosomes. These data provide the first direct evidence that nonmosaic Robertsonian translocations, as well as isochromosomes, are commonly the result of a mitotic exchange.

The OZF gene encodes a protein consisting essentially of zinc finger motifs.

A novel member of the zinc finger Krüppel family was isolated as a cDNA clone from the human mammary cell line HBL100. It contains an open reading frame consisting of 32 amino acid residues followed by ten zinc finger motifs and was accordingly named OZF (Only Zinc Fingers). Assuming that translation initiation starts at the unique methionine codon, 22 codons downstream of the beginning of the open reading frame as suggested by in vitro translation of OZF mRNA, the OZF protein is 292 residues long and has an estimated molecular mass of 33 kDa. The OZF gene is located in band q13.1 of the long arm of human chromosome 19. It is expressed as a single mRNA in liver, skeletal muscle and mammary cells and as two mRNA species in heart muscle. Absent or very low levels of expression were observed in brain, lung, placenta, kidney and human fibroblasts in culture. Thus, the OZF protein, which consists essentially of a DNA/RNA binding domain, may act as a tissue-specific modulator of gene expression.