Frequencies of Functional Polymorphisms in Three Pharmacokinetic Genes of Clinical Interest within the Admixed Puerto Rican Population.

OBJECTIVE: This cross-sectional study was aimed at determining the allele frequencies for the CYP2C19*2, CYP2C19*3, CYP2D6*10 and PON1 (rs662) polymorphisms in the Puerto Rican population. The CYP2C19, CYP2D6 and PON1 genes are known to be associated with functional changes in drug metabolism and activation. Individuals carrying the aforementioned polymorphisms are at a higher risk of suffering from drug-induced adverse events and/ or unresponsiveness from a variety of drugs that includes antidepressants, atypical antipsychotics and antiplatelet compounds. Information on the frequency of these polymorphisms is more commonly found on homogeneous populations, but is scarce in highly heterogeneous populations like Hispanics, as in the case of Puerto Ricans. METHOD: Genotyping was carried out in 100 genomic DNA samples from dried blood spots supplied by the Puerto Rican Newborn Screening program using Taqman® Genotyping Assays. RESULTS: The Minor Allele Frequencies (MAF) obtained were 9% for CYP2C19*2 and CYP2D6*10, 50% for PON1 (rs662), while the CYP2C19*3 variant was not detected in our study. Furthermore, Hardy Weinberg equilibrium analysis was assessed as well as a comparison between Puerto Rico and other reference populations using a Z-test for proportions. CONCLUSION: The observed allele and genotype frequencies on these relevant pharmacogenes in Puerto Ricans were more closely related to those early reported in two other reference populations of Americans (Mexicans and Colombians).

First case of dizygotic twins with lamellar ichthyosis in Puerto Rico.

Lamellar Ichthyosis is a rare condition requiring thickened collodion-like skin for clinical diagnosis. These infants have abnormal epidermal barrier, which leads to serious complications. It may present with extensive skin lesions and should be considered a diagnostic possibility in sick neonates. Recent studies have identified a condition characterized by deficiency of the interleukin-1 receptor antagonist (DIRA) resembling Ichthyosis. We report dizygotic twins that presented lamellar ichthyosis. Twin #1 had a neonatal period complicated with sepsis, fungemia and urinary tract infection. Twin #2 had sepsis, urinary tract infection and conjunctivitis. We tested the parents and one patient for DIRA. Tests were negative. To our knowledge, this is the first case of dizygotic twins that presented with lamellar ichthyosis in Puerto Rico. Physicians should include DIRA in the differential diagnosis of skin lesions in newborns.

Hemostatic matrix application after open synovectomy in a hemophilic patient.

Recurrent, spontaneous bleeding is common in patients with hemophilia. The joints are commonly and repeatedly affected, and this can result in chronic synovitis and joint damage. Synoviorthesis or synovectomy are indicated after failure of appropriate medical management. Hemostasis in the perioperative period is paramount in these patients. We report a case study of a patient with hemophilia A inhibitors undergoing open synovectomy complicated by postoperative bleeding. In addition to an infusion of bypassing agents due to the presence of inhibitors, a topical hemostatic agent, FLOSEAL, and absorbable Gelfoam were applied. Hemostasis was achieved rapidly. The patient recovered without complications.

Prevalence of a loss-of-function mutation in the proton-coupled folate transporter gene (PCFT-SLC46A1) causing hereditary folate malabsorption in Puerto Rico.

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.

Newborn screening for hermansky-pudlak syndrome type 3 in Puerto Rico.

BACKGROUND: Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by albinism, mucocutaneous bleeding, and storage of ceroid material in macrophages. Patients who are not easily identified by physical characteristics (mostly HPS-3 patients) may have hemorrhagic complications with trauma or surgery. OBJECTIVE: To determine the prevalence of HPS-3 in Puerto Rican newborns using DNA pooling technique. DESIGN/METHODS: Twelve percent of annual Puerto Rican births were tested randomly by polymerase chain reaction for the HPS-3 mutation, using pooled DNA extracted from dried blood samples. RESULTS: HPS-3 mutation was detected in 75 samples. Two newborns were found to be homozygous. Carrier frequency was 1:85 (1.18%). CONCLUSIONS: The HPS-3 carrier frequency found (1.18%) justifies universal newborn screening in Puerto Rico. DNA pooling reduces time and labor in newborn screening thus facilitating early diagnosis and treatment of children with HPS-3 and the provision of genetic counseling to parents and relatives.

Physiogenomic analysis of the Puerto Rican population.

AIMS: Admixture in the population of the island of Puerto Rico is of general interest with regards to pharmacogenetics to develop comprehensive strategies for personalized healthcare in Latin Americans. This research was aimed at determining the frequencies of SNPs in key physiological, pharmacological and biochemical genes to infer population structure and ancestry in the Puerto Rican population. MATERIALS & METHODS: A noninterventional, cross-sectional, retrospective study design was implemented following a controlled, stratified-by-region, random sampling protocol. The sample was based on birthrates in each region of the island of Puerto Rico, according to the 2004 National Birth Registry. Genomic DNA samples from 100 newborns were obtained from the Puerto Rico Newborn Screening Program in dried-blood spot cards. Genotyping using a physiogenomic array was performed for 332 SNPs from 196 cardiometabolic and neuroendocrine genes. Population structure was examined using a Bayesian clustering approach as well as by allelic dissimilarity as a measure of allele sharing. RESULTS: The Puerto Rican sample was found to be broadly heterogeneous. We observed three main clusters in the population, which we hypothesize to reflect the historical admixture in the Puerto Rican population from Amerindian, African and European ancestors. We present evidence for this interpretation by comparing allele frequencies for the three clusters with those for the same SNPs available from the International HapMap project for Asian, African and European populations. CONCLUSION: Our results demonstrate that population analysis can be performed with a physiogenomic array of cardiometabolic and neuroendocrine genes to facilitate the translation of genome diversity into personalized medicine.

Prevalence of combinatorial CYP2C9 and VKORC1 genotypes in Puerto Ricans: implications for warfarin management in Hispanics.

Polymorphisms in the cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) genes significantly alter the effective warfarin dose. We determined the frequencies of alleles, single carriers, and double carriers of single nucleotide polymorphisms (SNPs) in the CYP2C9 and VKORC1 genes in a Puerto Rican cohort and gauged the impact of these polymorphisms on warfarin dosage using a published algorithm. A total of 92 DNA samples were genotyped using Luminex x-MAP technology. The polymorphism frequencies were 6.52%, 5.43% and 28.8% for CYP2C9 *2, *3 and VKORC1-1639 C>A polymorphisms, respectively. The prevalence of combinatorial genotypes was 16% for carriers of both the CYP2C9 and VKORC1 polymorphisms, 9% for carriers of CYP2C9 polymorphisms, 35% for carriers of the VKORC1 polymorphism, and the remaining 40% were non-carriers for either gene. Based on a published warfarin dosing algorithm, single, double and triple carriers of functionally deficient polymorphisms predict reductions of 1.0-1.6, 2.0-2.9, and 2.9-3.7 mg/day, respectively, in warfarin dose. Overall, 60% of the population carried at least a single polymorphism predicting deficient warfarin metabolism or responsiveness and 13% were double carriers with polymorphisms in both genes studied. Combinatorial genotyping of CYP2C9 and VKORC1 can allow for individualized dosing of warfarin among patients with gene polymorphisms, potentially reducing the risk of stroke or bleeding.

Evidenced based management of neonatal hemangiolymphangioma: a case report.

Hemangiolymphangioma is a mixed vascular malformation that is detected in the prenatal period by sonography. Five cases of prenatal diagnosis have been reported that have resulted in termination of pregnancy (two) or aggressive versus purely surgical post-natal management. We present the case of an infant with pre-natal diagnosis of a multicystic intra-abdominal mass that received surgical management followed by conservative treatment.

Genetic testing for oculocutaneous albinism type 1 and 2 and Hermansky-Pudlak syndrome type 1 and 3 mutations in Puerto Rico.

Hermansky-Pudlak syndrome (HPS) (MIM #203300) is a heterogeneous group of autosomal recessive disorders characterized by oculocutaneous albinism (OCA), bleeding tendency, and lysosomal dysfunction. HPS is very common in Puerto Rico (PR), particularly in the northwest part of the island, with a frequency of approximately 1:1,800. Two HPS genes and mutations have been identified in PR, a 16-base pair (bp) duplication in HPS1 and a 3,904-bp deletion in HPS3. In Puerto Ricans with more typical OCA, the most common mutation of the tyrosinase (TYR) (human tyrosinase (OCA1) gene) gene was G47D. We describe screening 229 Puerto Rican OCA patients for these mutations, and for mutations in the OCA2 gene. We found the HPS1 mutation in 42.8% of cases, the HPS3 deletion in 17%, the TYR G47D mutation in 3.0%, and a 2.4-kb deletion of the OCA2 gene in 1.3%. Among Puerto Rican newborns, the frequency of the HPS1 mutation is highest in northwest PR (1:21; 4.8%) and lower in central PR (1:64; 1.6%). The HPS3 gene deletion is most frequent in central PR (1:32; 3.1%). Our findings provide insights into the genetics of albinism and HPS in PR, and provide the basis for genetic screening for these disorders in this minority population.

Poor response to desmopressin acetate (DDAVP) in children with Hermansky-Pudlak syndrome.

BACKGROUND: Hermansky-Pudlak syndrome (HPS) is a common genetic disorder in Puerto Rico. In children with HPS, bleeding is the most disturbing and incapacitating problem. Desmopressin (1-deamino-8-D-arginine vasopressin, (DDAVP)) has been recommended in the management of bleeding disorders characterized by platelet dysfunction, such as HPS. METHODS: Nineteen pediatric Puerto Rican patients with HPS and prolonged bleeding time (BT) were tested for response to administration of DDAVP. RESULTS: Baseline BT was abnormal in 18 (95%) of the patients. The BT following DDAVP administration improved in two cases (11%): one from 7.2 to 5.6 min and the other from 8 to 6 min (Tables II and III). BT measurements remained very prolonged (>15 min) in 17 (89%) of the patients. Patients with the HPS 1 gene mutation had a statistically significant correlation with the poor response following DDAVP (P = 0.03). CONCLUSIONS: 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.

Severe neutropenia in an infant with methylmalonic acidemia.

Neutropenia exists when the neutrophil counts is less than 1000/mm3 in infants between 2 weeks and 1 year of age and less than 1500/mm3 beyond 1 year of age (1). Severe infections occur when the absolute neutrophil count is below 500/mm3 with perirectal abscesses, pneumonia, and sepsis being common. Granulocyte Colony-Stimulating Factor (G-CSF) produces a sustained neutrophil recovery in patients with severe neutropenia, reduces the incidence and severity of infection, and improves the quality of life. Various cytopenias, including neutropenia, thrombocytopenia and pancytopenia, have been reported in association with inborn errors of branched aminoacid metabolism such as methylmalonic, propionic and isovaleric acidemia. We report an infant with methylmalonic acidemia who presented severe neutropenia.

Response of patients with hemophilia A and von Willebrand disease to desmopressin (DDAVP)

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 ug/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 hemophiliaacs, 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