Uniparental disomy causes deficiencies of vitamin K-dependent proteins

Essentials Vitamin K-dependent coagulant factor deficiency (VKCFD) is a rare autosomal recessive disorder. We describe a case of inherited VKCFD due to uniparental disomy. The homozygous mutation caused the absence of GGCX isoform 1 and overexpression of Δ2GGCX. Hepatic and non-hepatic vitamin K-dependent proteins must be assayed to monitor VKCFD treatment.

SUMMARY

Background Inherited deficiency of all vitamin K-dependent coagulant factors (VKCFD) is a rare autosomal recessive disorder caused by mutations in the γ-glutamyl carboxylase gene (GGCX) or the vitamin K epoxide reductase gene (VKORC1), with great heterogeneity in terms of both clinical presentation and response to treatment. Objective To characterize the molecular basis of VKCFD in a Spanish family. Methods and Results Sequencing of candidate genes, comparative genomic hybridization and massive sequencing identified a new mechanism causing VKCFD in the proband. Uniparental disomy (UPD) of chromosome 2 caused homozygosity of a mutation (c.44-1G>A) resulting in aberrant GGCX splicing. This change contributed to absent expression of the mRNA coding for the full-length protein, and to four-fold overexpression of the smaller mRNA isoform lacking exon 2 (Δ2GGCX). Δ2GGCX might be responsible for two unexpected clinical observations in the patient: (i) increased plasma osteocalcin levels following vitamin K1 supplementation; and (ii) a mild non-bleeding phenotype. Conclusions Our study identifies a new autosomal disease, VKCFD1, caused by UPD. These data suggest that the Δ2GGCX isoform may retain enzymatic activity, and strongly encourage the evaluation of both hepatic and non-hepatic vitamin K-dependent proteins to assess differing responses to vitamin K supplementation in VKCFD patients.

Simultaneous detection and typing of plum pox potyvirus (PPV) isolates by heminested-PCR and PCR-ELISA

Two techniques for simultaneous detection and typing of plum pox potyvirus (PPV) isolates belonging to the D or M serotypes, heminested PCR (H-PCR) and PCR-ELISA, have been developed. Ten PPV isolates typed using PPV-D and PPV-M specific monoclonal antibodies by ELISA-DASI were used to validate these two methods. The results obtained show a complete coincidence of the nucleic acid-based techniques with the serological data. When serial dilutions of infected plant extracts were assayed, H-PCR and PCR-ELISA were found to be 100 times more sensitive than the more conventional immunocapture-PCR (IC-PCR) assay. Testing of 228 PPV-infected fruit tree samples coming from different hosts and locations indicated that so far only PPV type D appears to be present in Spain and in Chile. Coupled with print-capture sample preparation (Olmos et al., Nucl. Acids Res. 24, 2192-2193, 1996) the increased sensitivity provided by heminested-PCR allowed the detection of PPV targets of D and M types, in wingless individuals of the aphid vector Aphis gossypii.

DNA amplification fingerprinting for subtyping Neisseria gonorrhoeae strains

BACKGROUND AND OBJECTIVES

DNA amplification fingerprinting is used in most epidemiologic studies as a substitute for conventional typing methods. DNA amplification fingerprinting and conventional typing methods were compared in this epidemiologic study of Neisseria gonorrhoeae.

GOAL OF THIS STUDY

To differentiate 70 Neisseria gonorrhoeae isolates from untreated patients with urogenital gonococcal infection.

STUDY DESIGN

Gonococcal strains were characterized by auxotyping, serotyping, plasmid profile, antibiotic sensitivity, and DNA amplification fingerprinting. The method of unweighted pair-group average linkage was used for cluster analysis. Discriminatory power was calculated applying Simpson's index.

RESULTS

Amplification of Neisseria gonorrhoeae DNA with primers OPA-03 and OPA-13 produced well-resolved patterns of 15 and 22 DNA fragments, respectively, with a discriminatory power (0.978 with OPA-13 and 0.967 with OPA-03) comparable to that obtained with auxotyping/serotyping combination (D:0.968) or with auxotype/serotype/plasmid profile combination (D:0.983). Correlation between DNA amplification fingerprinting pattern and auxotype/serotype class was not always uniform. Some strains with the same auxotype/serotype/plasmid profile were subdivided by DNA amplification fingerprinting, and vice versa.

CONCLUSION

Although auxotype/serotype class and DNA amplification fingerprinting can be used in the epidemiologic characterization of strains, DNA amplification fingerprinting offers a better discriminatory index than the separate serotyping. It is especially useful for differentiating serologically identical strains and nontypable strains. A combination of serotyping and DNA amplification fingerprinting seems to be the best way to differentiate Neisseria gonorrhoeae strains in epidemiologic studies, bringing together the most simple techniques and the best discriminatory power among isolates.

Nested polymerase chain reaction for detection of Legionella pneumophila in water

A highly sensitive nested polymerase chain reaction (PCR) method was evaluated for detection of Legionella pneumophila in water. Two sets of primers homologous to the coding region of the L. pneumophila macrophage infectivity potentiator (mip) gene were used. Even when starting from minute amounts of L. pneumophila DNA, the double PCR products were readily detected by direct visualization in ethidium-bromide-stained agarose gels. The method was tested on 34 potable water samples from a hospital building and compared with standard culture isolation. L. pneumophila was isolated in only twelve samples, whereas, by nested PCR, 19 samples were positive, 12 of them coincidental with culturing. These results indicate that nested PCR permits detection of L. pneumophila in samples where culturing fails, with the advantage of a rapid turnaround time, simplicity and the ability to detect non-culturable cells, fulfilling the requirements of sensitivity and specificity for routine use in an environmental laboratory.

Genomic fingerprinting of penicillinase-producing strains of Neisseria gonorrhoeae in Valencia, Spain

OBJECTIVE

To compare the value of different markers and their combinations with the restriction enzyme technique in the differentiations of penicillinase-producing N. gonorrhoeae (PPNG) strains.

MATERIALS AND METHODS

17 PPNG strains isolated from symptomatic, untreated male patients with urethritis were characterised by antibiotic sensitivity testing, auxotyping, serotyping, plasmid profile, and restriction endonuclease fingerprinting (Hind III digestion). Cluster analysis with the method of unweighted pair-group average (UPGMA) linkage was used to calculate similarity or dissimilarity for PPNG strains.

MAIN RESULTS

Either auxotyping or plasmid profile alone differentiated three groups of PPNG strains, whereas the combination auxotyping/serotyping identified 10. Although the combination auxotyping/serotyping/plasmid profile and the restriction enzyme technique showed a similar discrimination ability (differentiation of 11 PPNG strains), genomic fingerprinting gave highly specific restriction patterns on individual gonococcal isolates.

CONCLUSIONS

The combination of different markers gave more epidemiological information than the use of only one. The sequence of discriminating ability for PPNG strains was: auxotyping/serotyping less than auxotyping/serotyping/plasmid profile less than restriction patterns of genomic DNA.

[Membrane proteins electrophoretic profiles study applied to Neisseria gonorrhoeae epidemiology]

The analysis of electrophoretic profiles of membrane proteins is one of the epidemiological methods of bacterial typing. The profiles of membrane proteins of 95 isolates were studied for valuing their usefulness in the epidemiology of N. gonorrhoeae. The results were compared with the obtained using other characterization methods (auxotyping, serotyping and antimicrobial sensibility). The proteins I and II (PI and PII) showed clear differences between isolates. Only protein-I (PI) with constant molecular weight for each isolate was valid to discriminate between strains. It was observed correlation between serovariety IA and molecular weight of PI 33.6-36 kD, and the serovariety IB with molecular weight 35.5-37 kD. Though it wasn't possible discriminated between the different serovarieties. It was proved a sensibility decrease to penicillin, tetracycline and cloramfenicol in those strains with molecular weight of PI greater than 35.5 kD (serogroup WII/WIII). In the 80% of the isolates considered multiple antibiotic-resistant it was observed a significant increase of the membrane protein dough of 52 kD. All the strains with this protein increased were multiple antibiotic-resistant.