Miguel Angel Alcántara-Ortigoza

Analysis of the CTNS Gene in Nephropathic Cystinosis Mexican Patients: Report of Four Novel Mutations and Identification of a False Positive 57-kb Deletion Genotype with LDM-2/Exon 4 Multiplex PCR Assay

OBJECTIVE Identify CTNS gene mutations in nephropathic cystinosis Mexican patients. SUBJECTS AND METHODS Eleven patients were included, nine presenting infantile nephropathic cystinosis and two siblings with the juvenile phenotype. The common 57-kb deletion was detected by multiplex PCR using large deletion marker-2 (LDM-2)/exon 4 set primers. Those alleles negative for 57-kb deletion were screened by single strand confirmation polymorphism (SSCP) and subsequent direct sequencing. RESULTS In our sample, five mutations previously reported are identified: 57-kb deletion, EX4_EX5del, c.985_986insA, c.357_360delGACT, and c.537_557del. We detect a false assignation of 57-kb deletion homozygous genotype by using the LDM-2/exon 4 primers. In addition, four novel and severe mutations are identified: c.379delC, c.1090_1093delACCAinsCG, c.986C>G (p.T216R), and c.400+5G>A. CONCLUSIONS Our sample of Mexican patients display allelic heterogeneity as compared to European or North American cystinosis cases. The identification of novel mutations might suggest the presence of exclusive American CTNS alleles in Mexican population. In order to prevent the false positive assignation of 57-kb deletion genotype, as caused by the presence of another type of intragenic CTNS gross deletion, we propose to analyze a different control CTNS exon to those originally reported in both LDM multiplex PCR assays, especially when parental DNA samples are not available.

Association of Interactions Among the IRF6 Gene, the 8q24 Region, and Maternal Folic Acid Intake With Non-Syndromic Cleft Lip/Palate in Mexican Mestizos

Association of Interactions Among the IRF6 Gene, the 8q24 Region, and Maternal Folic Acid Intake With Non-Syndromic Cleft Lip/Palate in Mexican Mestizos Jos!e A. Vel!azquez-Arag!on, Miguel A. Alc!antara-Ortigoza, Bernardette Estandia-Ortega, Miriam E. Reyna-Fabi!an, Carlos Cruz-Fuentes, Sandra Villag!omez, and Ariadna Gonz!alez-del Angel* Laboratorio de Biolog!ia Molecular, Departamento de Gen!etica Humana, Instituto Nacional de Pediatr!ia, Avenida Insurgentes Sur 3700-C, Insurgentes Cuicuilco, Coyoac!an, Distrito Federal, Mexico Departamento de Gen!etica, Subdirecci!on de Investigaciones Cl!inicas, Instituto Nacional de Psiquiatr!ia Ram!on de la Fuente, Calzada M!exico-Xochimilco 101, San Lorenzo Huipulco, Tlalpan, Distrito Federal, Mexico Unidad de Apoyo a la Investigaci!on Cl!inica, Subdirecci!on de Investigaci!on M!edica, Instituto Nacional de Pediatr!ia, Avenida Insurgentes Sur 3700-C, Insurgentes Cuicuilco, Coyoac!an, Distrito Federal, Mexico

Thiopurine S-methyltransferase (TPMT) genetic polymorphisms in Mexican newborns

Background:  Thiopurine S‐methyltransferase (TPMT) is involved in the toxicity and therapeutic efficacy of thiopurine drugs, and its gene exhibits genetic polymorphisms that differ across diverse populations. Four TPMT polymorphisms (TPMT*2, *3A, *3B and *3C) account for 80–95% of alleles that cause reduced enzyme activity. To date, only a single study in the Mexican population involving 108 individuals has been performed, but the regional and ethnic origin of this population was not described. Accordingly, information about the TPMT polymorphism in the Mexican population is limited.

Effects of Fructans from Mexican Agave in Newborns Fed with Infant Formula: A Randomized Controlled Trial.

Background: The importance of prebiotics consumption is increasing all over the world due to their beneficial effects on health. Production of better prebiotics from endemic plants raises possibilities to enhance nutritional effects in vulnerable population groups. Fructans derived from Agave Plant have demonstrated their safety and efficacy as prebiotics in animal models. Recently, the safety in humans of two fructans obtained from Agave tequilana (Metlin® and Metlos®) was demonstrated. Methods: This study aimed to demonstrate the efficacy as prebiotics of Metlin® and Metlos® in newborns of a randomized, double blind, controlled trial with a pilot study design. Biological samples were taken at 20 ± 7 days, and three months of age from healthy babies. Outcomes of efficacy include impact on immune response, serum ferritin, C-reactive protein, bone metabolism, and gut bacteria changes. Results: There were differences statistically significant for the groups of infants fed only with infant formula and with formula enriched with Metlin® and Metlos®. Conclusions: Our results support the efficacy of Metlin® and Metlos® as prebiotics in humans, and stand the bases to recommend their consumption. Trial Registration: ClinicalTrials.gov, NCT 01251783.

Phenylalanine hydroxylase deficiency in Mexico: genotype–phenotype correlations, BH4 responsiveness and evidence of a founder effect

The mutational spectrum of the phenylalanine hydroxylase gene (PAH) in Mexico is unknown, although it has been suggested that PKU variants could have a differential geographical distribution. Genotype–phenotype correlations and genotype‐based predictions of responsiveness to tetrahydrobiopterin (BH4) have never been performed. We sequenced the PAH gene and determined the geographic origin of each allele, mini‐haplotype associated, genotype–phenotype correlations and genotype‐based prediction of BH4 responsiveness in 48 Mexican patients. The mutational spectrum included 34 variants with c.60+5G>T being the most frequent (20.8%) and linked to haplotype 4.3 possibly because of a founder effect and/or genetic drift. Two new variants were found c.1A>T and c.969+6T>C. The genotype–phenotype correlation was concordant in 70.8%. The genotype‐based prediction to BH4‐responsiveness was 41.7%, this information could be useful for the rational selection of candidates for BH4 testing and therapy.

Screening of Late-Onset Pompe Disease in a Sample of Mexican Patients With Myopathies of Unknown Etiology: Identification of a Novel Mutation in the Acid α-glucosidase Gene

Pompe disease or glycogen-storage disease type 2 (GSD2, OMIM 232300) is an autosomal recessive disorder caused by mutations in the acid α-glucosidase gene. Late-onset GSD2 resembles some limb-girdle and Becker muscular dystrophies. The screening of GSD2 through the measurement of acid α-glucosidase activity in dried blood spots was applied to a selected sample of 5 Mexican patients with proximal myopathies of unknown etiology. Only 1 male patient showed a low level of acid α-glucosidase activity and a compound heterozygote genotype for the c.-32-13T>G splicing mutation present in most white late-onset Pompe disease cases and the novel mutation p.C558S. To our knowledge, this is the first report of a Mexican patient with late-onset GSD2. The identification of c.-32-13T>G in our patient could reflect the genetic contribution of European ancestry to the Mexican population. The enzymatic screening of GSD2 could be justified in patients with myopathies of unknown etiology.

Gene Interactions Provide Evidence for Signaling Pathways Involved in Cleft Lip/Palate in Humans

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is a common craniofacial birth defect that has a complex etiology. Genome-wide association studies have recently identified new loci associated with NSCL/P, but these loci have not been analyzed in a Mexican Mestizo population. A complex etiology implies the presence of genetic interactions, but there is little available information regarding this in NSCL/P, and no signaling pathway has been clearly implicated in humans. Here, we analyzed the associations of 24 single nucleotide polymorphisms (SNPs) with NSCL/P in a Mexican Mestizo population (133 cases, 263 controls). The multifactorial dimensionality reduction method was used to examine gene–gene and gene–folic acid consumption interactions for the 24 SNPs analyzed in this study and for 2 additional SNPs that had previously been genotyped in the same study population. Six SNPs located in paired box 7, ventral anterior homeobox 1, sprouty RTK signaling antagonist 2, bone morphogenetic protein 4, and tropomyosin 1 genes were associated with higher risks of NSCL/P (P = 0.0001 to 0.04); 2 SNPs, 1 each in netrin 1 and V-maf avian musculoaponeurotic fibrosarcoma oncogene homolog B, were associated with a lower risk of NSCL/P (P = 0.013 to 0.03); and 2 SNPs, 1 each in ATP binding cassette subfamily A member 4 (ABCA4) and noggin, showed associations with NSCL/P that approached the threshold of significance (P = 0.056 to 0.07). In addition, 6 gene–gene interactions (P = 0.0001 to 0.001) and an ABCA4–folic acid consumption interaction (P < 0.0001) were identified. On the basis of these results, combined with those of previous association studies in the literature and biological characterizations of murine models, we propose an interaction network in which interferon regulatory factor 6 plays a central role in the etiology of NSCL/P.

Wide allelic heterogeneity with predominance of large IDS gene complex rearrangements in a sample of Mexican patients with Hunter syndrome.

Hunter syndrome or mucopolysaccharidosis type II (MPSII) is caused by pathogenic variants in the IDS gene. This is the first study that examines the mutational spectrum in 25 unrelated Mexican MPSII families. The responsible genotype was identified in 96% of the families (24/25) with 10 novel pathogenic variants: c.133G>C, c.1003C>T, c.1025A>C, c.463_464delinsCCGTATAGCTGG, c.754_767del, c.1132_1133del, c.1463del, c.508‐1G>C, c.1006+1G>T and c.(‐217_103del). Extensive IDS gene deletions were identified in four patients; using DNA microarray analysis two patients showed the loss of the entire AFF2 gene, and epilepsy developed in only one of them. Wide allelic heterogeneity was noted, with large gene alterations (e.g. IDS/IDSP1 gene inversions, partial to extensive IDS deletions, and one chimeric IDS‐IDSP1 allele) that occurred at higher frequencies than previously reported (36% vs 18.9–29%). The frequency of carrier mothers (80%) is consistent with previous descriptions (>70%). Carrier assignment allowed molecular prenatal diagnoses. Notably, somatic and germline mosaicism was identified in one family, and two patients presented thrombocytopenic purpura and pancytopenia after idursulfase enzyme replacement treatment. Our findings suggest a wide allelic heterogeneity in Mexican MPSII patients; DNA microarray analysis contributes to further delineation of the resulting phenotype for IDS and neighboring loci deletions.

Molecular analysis of the PAX8 gene in a sample of Mexican patients with primary congenital hypothyroidism: identification of the recurrent p.Arg31His mutation.

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Erratum to: Germline Mutations in NKX2-5, GATA4, and CRELD1 are Rare in a Mexican Sample of Down Syndrome Patients with Endocardial Cushion and Septal Heart Defects [Pediatric Cardiology, 36, (2015), 802-808, DOI:10.1007/s00246-014-1091-3]

4 Unidad de Apoyo a la Investigación Clı́nica, Instituto Nacional de Pediatrı́a, Secretarı́a de Salud, Insurgentes Sur 3700-C, Insurgentes-Cuicuilco, Coyoacán, CP 04530 Mexico, Distrito Federal, Mexico 5 Unidad de Genómica y Secuenciación Masiva, Subdirección de Investigación Básica, Instituto Nacional de Cancerologı́a, San Fernando Número 22, Sección XVI, Tlalpan, CP 14080 Mexico, Distrito Federal, Mexico