DDAVP seldom improves the BT of Puerto Rican children with HPS. Response to DDAVP should be determined individually and platelet transfusion should remain the treatment of choice for a major bleeding episode or surgical procedure.

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.

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Hemoglobin S is the most common abnormal hemoglobin detected in newborn screening in Puerto Rico. The purpose of this report is to present laboratory and clinical data from a newborn proven to have combined heterozygocity for hemoglobin S and a very rare hemoglobin. Abnormal newborn screening results using isoelectric focusing prompted us to further study an infant with an unknown hemoglobin. Testing with cellulose acetate and citrate agar electrophoresis revealed that this patient had, besides hemoglobin S, a rare fast moving band. We consulted the Haemoglobinopathy Screening Service at St. James’s University Hospital in Leeds, UK where our patient’s hemoglobin was identified as hemoglobin Porto Alegre by means of mass spectrometry. DNA sequencing at the molecular genetics laboratory in the Medical Sciences Campus, University of Puerto Rico confirmed our patient’s hemoglobin to be Hb Porto Alegre. The patient’s father was found to be heterozygous for hemoglobin S and her mother a carrier of hemoglobin Porto Alegre. Our patient has been followed-up for the last two years. She has remained asymptomatic, except for usual mild childhood diseases. Laboratory results up to 18 months of age have revealed Hgb 11.4–11.6 g/dl, MCV 87.5 fl, MCH 28.7 pg, reticulocyte count 2%, normal total bilirubin and LDH levels. Hemoglobin Porto Alegre involves a mutation in ß9(A6)Ser→Cys which promotes hemoglobin polymerization via disulfide bonds (Baudin-Creuza 2002). This mutation does not seem to alter hemoglobin function and apparently does not increase tendency for sickling. Tondo (1963) has reported that in vivo hemoglobin Porto Alegre exists in its normal tetrameric form, with no associated hemolysis. Martinez (1977) has suggested that hemoglobin Porto Alegre can exist in its tetrameric functional form by means of high levels of glutathione in red blood cells. Therefore, patients with combined hemoglobin S and Porto Alegre would be expected to be asymptomatic. Hemoglobin Porto Alegre has been documented in a few patients from Brazil, Portugal, Argentina, Cuba, and the Canary Islands. To our knowledge this is the first reported double heterozygote for hemoglobin S and Porto Alegre. We are following our patient closely for the development of any significant hematologic or clinical symptoms.