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.

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BackgroundPigmentary mosaicism constitutes a heterogeneous group of skin pigmentation alterations associated with multisystem involvement. The aim of this study was to establish a complete cytogenetic and molecular characterization of PM patients, emphasizing on searching for possible low chromosomal mosaicism and on establishing an accurate genotype-phenotype correlation.ResultsA total of 73 patients were included (3 months to 18 years of age), 52% male and 48% female. Observed in 69 (95%) patients, the most frequent pattern of pigmentation was fine and whorled BL, which was associated with disseminated skin extent in 41 (59%) patients. Central nervous system (84%) alterations were the most frequent observed in the group of patients, followed by the musculoskeletal (53%) and ophthalmologic (27%) alterations. Considering the pattern of pigmentation, no significant differences in association with skin extent or extracutaneous manifestations were detected. Following a strict cytogenetic analysis strategy, screening metaphases from three different tissues (peripheral blood, hyperpigmented and hypopigmented skin) we found that 23/73 patients had chromosomal abnormalities classified as follows: 1) Mosaic with 2 or more different cell lines with structural alterations n = 19; 2) Polyploidy (mosaic) n = 1 and 3) Alterations in all cells in three different tissues n = 3. SNP array, array CGH and FISH were useful for the complete characterization of the chromosomal aberrations, for the detection of microdeletions in patients with normal karyotype but with strong clinical suspicious of chromosomal alteration, and for a better establishment of genotype-phenotype correlation. In 2 patients we found genes associated with some of the extracutaneous manifestations (SHH, MNX1, PPP2R2C).ConclusionsThis group of 73 patients finely described is the largest series of patients with pigmentary mosaicism reported worldwide. As we showed in this study, the followed analysis strategy allowed the detection of cytogenetic and molecular abnormalities, and made possible the establishment of genotype-phenotype associations in some patients. An important limitation of our study was the analysis of fibroblasts cultures instead of melanocytes and keratinocytes. In some cases the direct molecular DNA analysis of skin biopsy could be another choice.

This patient had a classic AHDS phenotype with an unexpectedly large anterior fontanel and delayed bone age and dentition. Bioinformatic analyses suggested that exon 1 deletions in patients with AHDS are caused by microhomology-mediated replicative-based and nonhomologous end-joining mechanisms. Rearrangement susceptibility may be due to the size of intron 1 and the percentage of repeat sequences.

Partial trisomies of the short arm of chromosome 5 are uncommon. The first description was made by Lejeune et al., in 1964. It has been suggested that the critical region for 5p trisomy syndrome lies between 5p10 and 5p13. We report on a Mexican girl who developed severe mental retardation and generalized tonic clonic seizures at age 1 year. On physical examination at age 5 years, she had macrodolichocephaly, upslanted palpebral fissures, bilateral inner epicanthic folds, low nasal root, and malformed ears with posterior rotation which are clinical characteristics of 5p trisomy syndrome. The cytogenetic study with G bands and FISH with painting for chromosome 5 and with the cri-du-chat 5p15 unique sequence probe showed a duplication and inversion of 5p [46,XX, dup(5)(p15.3 p13.3)] which overlaps with the critical region for 5p trisomy syndrome. Our patient shares clinical characteristics with the patients described in the literature with involvement of this critical region. Both parents have normal karyotypes indicating the rearrangement is de novo. Only one patient has been reported in the literature with the same cytogenetic rearrangement as our patient, but this patient had a different phenotype. Since they only performed conventional cytogenetics and we performed FISH to confirm the diagnosis, the differences in the phenotypes could be explained by the presence of other genes involved in the rearrangement. The combined use of conventional and molecular cytogenetics in this case allows a more precise diagnosis and furthers knowledge in phenotype/genotype correlation.

Non-syndromic cleft lip/palate (NSCL/P) is a common congenital defect in Mexico. Periconceptional intake of folic acid (FA) may reduce the risk of this malformation. Although the 5,10-methylenetetrahydrofolate reductase (MTHFR) enzyme participates in folate metabolism, several studies failed to find any association between NSCL/P and the MTHFR C677T and A1298C polymorphisms. However, interactions among NSCL/P, MTHFR gene polymorphisms, and FA intake have not been explored in Mexican populations. This case-control study included 132 patients with NSCL/P and 370 controls from Mexico City. Maternal FA consumption during pregnancy was examined, as were the MTHFR C677T and A1298C polymorphisms and gene-FA interactions. Maternal FA intake during the periconceptional period was lower in cases (1.5%) than in controls (13%), with the risk of delivering a child with NSCL/P lower in mothers who consumed FA (OR = 0.29, 95% CI: 0.19-0.44). In addition, the risk of NSCL/P was lower in children with the TT than the CC genotype of MTHFR C677T (OR = 0.39, 95% CI: 0.23-0.68), after Bonferroni correction and exclusion of stratification. No evidence of gene-FA interaction was found. These results indicate that maternal FA intake and the TT genotype of the MTHFR C677T polymorphism in children independently reduced the risk of NSCL/P in our population.

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.

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.