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Objective: To determine whether subjects of Puerto Rican heritage are at increased risk for a specific mutation of the proton-coupled folate transporter (PCFT) causing hereditary folate malabsorption (HFM). Study design: Three percent of the births in Puerto Rico in 2005, with additional regional oversampling, were screened for the prevalence of the c.1082G>A; p.Y362_G389 del PCFT gene mutation. Six new subjects of Puerto Rican heritage with the clinical diagnosis of HFM were also assessed for this mutation. Results: Six subjects of Puerto Rican heritage with the clinical diagnosis of HFM were all homozygous for the c.1082G>A; p.Y362_G389 del PCFT mutation. Three heterozygote carriers were identified from the 1582 newborn samples randomly selected from births in Puerto Rico in 2005. The carrier frequency for the mutated allele was 0.2% island-wide and 6.3% in Villalba. Conclusion: These findings are consistent with a common mutation in the PCFT gene causing HFM that has disseminated to Puerto Ricans who have migrated to mainland United States. Because prompt diagnosis and treatment of infants with HFM can prevent the consequences of this disorder, newborn screening should be considered in high-risk populations and physicians should be aware of its prevalence in infants of Puerto Rican ancestry. [ABSTRACT FROM AUTHOR]

Five unrelated families with Puerto Rican ancestry were identified as having at least one member with bleeding due to a prothrombin deficiency. Genetic prothrombin deficiencies are extremely rare, but at the University of Puerto Rico Hemophilia Center, prothrombin deficiency is the third most common congenital coagulation factor deficiency. Because Puerto Rico is relatively isolated, there was a reasonable expectation of a founder effect. Prothrombin genes from probands and their parents were directly sequenced from PCR amplified exons using forward and reverse primers. Four novel prothrombin mutations were identified. The first, a G-->A substitution at DNA position 10150 predicting an Arg457-->Gln (R457Q) replacement, is common to all five families. In two of the families, the proband children are homozygous for R457Q. In the other three families, the probands are compound heterozygotes for R457Q and one of the other three mutations, which include another point mutation (gamma16Q), a deletion and a splice junction mutation. The two point mutations have been designated Puerto Rico I and Puerto Rico II. The crystal structure of alpha-thrombin predicts that the R457Q mutation removes a salt bridge that links the A- and B-chains of thrombin. The primary effect of this defect appears to be destabilization of the circulating prothrombin, creating a moderate hypoprothrombinemia. However, prothrombin antigen/activity ratios indicate a dysprothrombinemia as well, most likely due to the inability of R457Q prothrombin to activate fully to thrombin.

The present cost of optimal care in haemophilia is very high. The paradigm of comprehensive care approach, including the essential elements of continuous integrated multidisciplinary health services and the provision of home care with early use of antihaemophilic products requires abundant economic resources that usually are not readily available in nonaffluent countries. A cost-effective comprehensive paediatric haemophilia programme has been operating in Puerto Rico during the last 15 years that provides quality care to over 90% of paediatric haemophiliacs, and is financed mainly by the local government health system. Efforts are also being made to provide and/or coordinate health care to all adult haemophilic patients through the Puerto Rico Pediatric Hemophilia Treatment Center. Information on the haemophilia care available in Latin American countries is scanty. The data available indicate that with a few exceptions, haemophilia care in this vast region is suboptimal. Apparently, early diagnosis is not common, there is lack of accessibility of services in most countries, comprehensive care is not the rule, safe high-purity AHF concentrates are used infrequently, and home care is used rarely. The main antihaemophilic products used are fresh frozen plasma and cryoprecipitate due to the high cost of modern antihaemophilic factor concentrates. The average per capita income of the main Latin American countries is about one-quarter of that of the USA and Canada. The existing economic situation of most Latin American countries would make it very difficult for them to purchase modern antihaemophilic products regularly and provide quality comprehensive care to their haemophilia patients, unless they make special efforts and get some type of external help. As a result of this study recommendations are made to improve the quality and accessibility of services to haemophilia patients in Latin America and other nonaffluent countries.

Factor VIII (FVIII) response to desmopressin (deamino-8-D-arginine vasopressin, abbreviated DDAVP) was studied in patients with mild Hemophilia A and von Willebrand Disease (vWD) who attend our Hemophilia Clinic. Thirty eight children and 9 adults had their F VIII components assayed 60 minutes after intravenous (IV) administration of DDAVP, 0.35 microgram/kg. Among 27 hemophiliacs, F VIII coagulant activity (F VIII: C) increased from a mean of 16.8 to 59.2 u/dL; with an average 3.2-fold increase. In 20 vWD patients, the mean F VIII:C and von Willebrand Factor increased from a mean of 50.1 to 136%; and from 22.6 to 75.6%; with an average 3.0 and 5.7-fold increase, respectively. The overall F VIII:C response was good or excellent in 81.5% of the hemophiliacs, and in 89.5% of the vWD patients tested. No significant side effects were observed. This study has demonstrated that IV DDAVP can cause an increase of F VIII:C and vWF to hemostatic levels, and thus it may be useful for the control of bleeding episodes in most of the patients tested in our clinic.