Risk of infectious mononucleosis among agonistic swimmers: a cross-sectional study.

BACKGROUND: The risk of infectious mononucleosis among athletes is quite debated. Some personal observations seem to suggest an increase risk of mononucleosis among athletes, because they attend always close settings with an high probability of respiratory pathogens transmission; overtraining has been also proposed as risk factor. STUDY DESIGN: Cross-sectional study in a group of swimmers (aged 11-14 years) of the University Sport Centre of Bari. METHODS: 40 swimmers were interviewed by healthcare personnel at the end of training courses; demographic characteristics, personal habits, information about sport training and diagnosis of mononucleosis were analysed. RESULTS: The life-time incidence of mononucleosis was around 40%; multivariate analysis showed the association between mononucleosis and use of bottles of other persons (aOR=8.2; 95% CI=1.4-49.2; z=2.32; p=0.021) and average duration of training session was longer among subjects who reported mononucleosis than in subjects who did not indicate this disease. CONCLUSIONS: Future multi-centric studies are needed to better define the epidemiology of the mononucleosis in sport settings and to formulate appropriate recommendations to prevent the spreading of this disease.

CDH23 mutation and phenotype heterogeneity: a profile of 107 diverse families with Usher syndrome and nonsyndromic deafness.

Usher syndrome type I is characterized by congenital hearing loss, retinitis pigmentosa (RP), and variable vestibular areflexia. Usher syndrome type ID, one of seven Usher syndrome type I genetic localizations, have been mapped to a chromosomal interval that overlaps with a nonsyndromic-deafness localization, DFNB12. Mutations in CDH23, a gene that encodes a putative cell-adhesion protein with multiple cadherin-like domains, are responsible for both Usher syndrome and DFNB12 nonsyndromic deafness. Specific CDH23 mutational defects have been identified that differentiate these two phenotypes. Only missense mutations of CDH23 have been observed in families with nonsyndromic deafness, whereas nonsense, frameshift, splice-site, and missense mutations have been identified in families with Usher syndrome. In the present study, a panel of 69 probands with Usher syndrome and 38 probands with recessive nonsyndromic deafness were screened for the presence of mutations in the entire coding region of CDH23, by heteroduplex, single-strand conformation polymorphism, and direct sequence analyses. A total of 36 different CDH23 mutations were detected in 45 families; 33 of these mutations were novel, including 18 missense, 3 nonsense, 5 splicing defects, 5 microdeletions, and 2 insertions. A total of seven mutations were common to more than one family. Numerous exonic and intronic polymorphisms also were detected. Results of ophthalmologic examinations of the patients with nonsyndromic deafness have found asymptomatic RP-like manifestations, indicating that missense mutations may have a subtle effect in the retina. Furthermore, patients with mutations in CDH23 display a wide range of hearing loss and RP phenotypes, differing in severity, age at onset, type, and the presence or absence of vestibular areflexia.

Genetic heterogeneity of Usher syndrome: analysis of 151 families with Usher type I.

Usher syndrome type I is an autosomal recessive disorder marked by hearing loss, vestibular areflexia, and retinitis pigmentosa. Six Usher I genetic subtypes at loci USH1A-USH1F have been reported. The MYO7A gene is responsible for USH1B, the most common subtype. In our analysis, 151 families with Usher I were screened by linkage and mutation analysis. MYO7A mutations were identified in 64 families with Usher I. Of the remaining 87 families, who were negative for MYO7A mutations, 54 were informative for linkage analysis and were screened with the remaining USH1 loci markers. Results of linkage and heterogeneity analyses showed no evidence of Usher types Ia or Ie. However, one maximum LOD score was observed lying within the USH1D region. Two lesser peak LOD scores were observed outside and between the putative regions for USH1D and USH1F, on chromosome 10. A HOMOG chi(2)((1)) plot shows evidence of heterogeneity across the USH1D, USH1F, and intervening regions. These results provide conclusive evidence that the second-most-common subtype of Usher I is due to genes on chromosome 10, and they confirm the existence of one Usher I gene in the previously defined USH1D region, as well as providing evidence for a second, and possibly a third, gene in the 10p/q region.

Genetic heterogeneity of Usher syndrome type II: localisation to chromosome 5q.

Usher syndrome is a group of autosomal recessive disorders that includes retinitis pigmentosa (RP) with hearing loss. Usher syndrome type II is defined as moderate to severe hearing loss with RP. The USH2A gene at 1q41 has been isolated and characterised. In 1993, a large Usher II family affected with a mild form of RP was found to be unlinked to 1q41 markers. Subsequent linkage studies of families in our Usher series identified several type II families unlinked to USH2A and USH3 on 3q25. After a second unlinked family with many affected members and a mild retinal phenotype was discovered, a genome search using these two large families showed another Usher II locus on 5q (two point lod = 3.1 at D5S484). To date, we have identified nine unrelated 5q linked families (maximum combined multipoint lod = 5.86) as well as three Usher II families that show no significant linkage to any known Usher loci. Haplotype analysis of 5q markers indicates that the new locus is flanked by D5S428 and D5S433. Review of ophthalmological data suggests that RP symptoms are milder in 5q linked families; the RP is often not diagnosed until patients near their third decade. Enamel hypoplasia and severe, very early onset RP were observed in two of the three unlinked families; dental anomalies have not been previously described as a feature of Usher type II.

Deep vein thrombosis of the legs: new therapy by means of low molecular weight heparins.

This open controlled study compared the effects of subcutaneous administration of two types of heparin in two groups of 40 patients each with deep vein thrombosis. One group received calcium heparin and the other received low molecular weight heparin for 40 days in each case. Patients receiving low molecular weight heparin showed a greater increase in inhibition of activated factor X than those receiving calcium heparin. Both drugs slightly reduced activated partial thromboplastin time. No patient experienced pulmonary embolism during the study. At the end of the study, maximum venous outflow was significantly higher in patients given low molecular weight heparin than in those given calcium heparin. No major side-effects were observed. This study showed that: (a) the anti-thrombotic effect of low molecular weight heparin was greater than for calcium heparin; and (b) low molecular weight heparin improved maximum venous outflow in approximately half of the patients, possibly by promoting or accelerating recanalization of the vessel.