Divergent phenotypes in Gaucher disease implicate the role of modifiers.

BACKGROUND: Gaucher disease is classified into neuronopathic and non-neuronopathic forms with wide phenotypic variation among patients sharing the same genotype. While homozygosity for the common L444P allele usually correlates with the neuronopathic forms, how a defined genotype leads to a phenotype remains unknown. METHODS: The genetic and epigenetic factors causing phenotypic differences were approached by a clinical association study in 32 children homozygous for the point mutation L444P. Direct sequencing and Southern blots were utilised to establish the genotype and exclude recombinant alleles. Glucocerebrosidase activity was measured in lymphoblast and fibroblast cell lines. RESULTS: Residual enzyme activity was highly variable and did not correlate with the observed clinical course. There was also a wide spectrum of phenotypes. Average age at diagnosis was 15 months, and slowed saccadic eye movements were the most prevalent finding. The most severe systemic complications and highest mortality occurred in splenectomised patients before the advent of enzyme replacement therapy (ERT). On ERT, as morbidity and mortality decreased, developmental and language deficits emerged as a major issue. Some trends related to ethnic background were observed. CONCLUSION: The wide clinical spectrum observed in the L444P homozygotes implicates the contribution of genetic modifiers in defining the phenotype in Gaucher disease.

Environmental factors in infertility.

In conclusion, several studies indicate that there is an association between cigarette smoking and adverse reproductive outcomes in women as well as men. Some studies indicate that alcohol consumption impairs the reproductive capacity of women. Exposures to PCE in the dry cleaning industry, toluene in the printing business, ethylene oxide and mixed solvents have been associated with decreased fecundity. Abnormalities in sperm production have been found in men exposed to radiant heat or heavy metals. Environmental exposure to chlorinated hydrocarbons (e.g., DDT, PCB, pentachlorophenol, hexachlorocyclohexane) has been associated with an increase in rates of miscarriage and endometriosis. Clinicians should counsel patients who are trying to achieve a successful pregnancy to stop smoking and limit alcohol intake. Clinicians can additionally counsel patients who are in contact with potentially harmful occupational and environmental toxicants to limit their exposure. It is important to recognize, however, that many of the studies to date are limited by small sample size, poor exposure assessment, poor outcome measurements, recruitment bias, or recall bias. Additional studies will be necessary to clarify the magnitude of risk associated with these factors.

The nucleotide sequence of the luxA and luxB genes of Xenorhabdus luminescens HM and a comparison of the amino acid sequences of luciferases from four species of bioluminescent bacteria.

The luxA and luxB genes of bioluminescent bacteria encode the alpha and beta subunits of luciferase, respectively. Sequences of the luxA and luxB genes of Xenorhabdus luminescens, the only terrestrial bioluminescent bacterium known, were determined and the amino acid sequence of luciferase deduced. The alpha subunit was found to contain 360 amino acids and has a calculated molecular weight of 41,005 Da, while the beta subunit contains 327 amino acids and has a calculated molecular weight of 37,684 Da. Alignment of this luciferase with the luciferases of three marine bacteria showed 196 (or 55%) conserved residues in the alpha subunit and 114 (or 35%) conserved residues in the beta subunit. The highest degree of homology between any two species was between the luciferases of X. luminescens and Vibrio harveyi with 84% identity in the alpha subunits and 59% identity in the beta subunits.

The nucleotide sequence of the luxE gene of Vibrio harveyi and a comparison of the amino acid sequences of the acyl-protein synthetases from V. harveyi and V. fischeri.

The luxE gene of bioluminescent bacteria encodes the acyl-protein synthetase component of the fatty acid reductase complex. The complex is responsible for converting tetradecanoic acid to the aldehyde which serves as a substrate in the luciferase-catalyzed reaction. The nucleotide sequence of the luxE gene of Vibrio harveyi was determined and the amino acid sequence of the acyl-protein synthetase deduced. The protein consists of 378 amino acid residues and has a molecular weight of 42,965 daltons. Alignment of the V. harveyi enzyme with the V. fischeri acyl-protein synthetase showed 62% identity.