Pantothenate kinase‐associated neurodegeneration (PKAN) is an autosomal recessive disorder characterized by iron accumulation in the brain, because of mutations in the PANK2 gene. Phenotypic and ...genotypic characteristics of 11 patients from five Mexican families with PKAN disease are reported. Sequencing of PANK2 confirmed the diagnosis. The 11 patients had dysarthria associated with dystonia and Parkinsonism in six. Brain magnetic resonance imaging (MRI) showed the ‘eye‐of‐the‐tiger’ sign in all patients. Three different mutations were identified, a novel one (p.A469P) and two (p.G219V and p.N404I) very rare. Homozygous sibs for the p.G219V mutation had a severe disease progression with early death. Dystonia predominated in the p.A469P/p.N404I compound heterozygous patients. Homozygous for p.N404I showed Parkinsonism, tics and personality and speech disorders. Early and late disease onset and variable expression was present in carriers of the different identified mutations. The ‘eye‐of‐the‐tiger’ is an excellent neuroimaging hallmark to predict PANK2 mutations. We detected a ‘cluster’ of patients harboring the p.N404I mutation, strongly suggesting a founder effect for this mutation. This is the first familial clinical‐genetic PKAN disease study accomplished in Mexico.
Deletions of 17p13.3, including the LIS1 gene, result in the brain malformation lissencephaly, which is characterized by reduced gyration and cortical thickening; however, the phenotype can vary from ...isolated lissencephaly sequence (ILS) to Miller-Dieker syndrome (MDS). At the clinical level, these two phenotypes can be differentiated by the presence of significant dysmorphic facial features and a more severe grade of lissencephaly in MDS. Previous work has suggested that children with MDS have a larger deletion than those with ILS, but the precise boundaries of the MDS critical region and causative genes other than LIS1 have never been fully determined. We have completed a physical and transcriptional map of the 17p13.3 region from LIS1 to the telomere. Using fluorescence in situ hybridization, we have mapped the deletion size in 19 children with ILS, 11 children with MDS, and 4 children with 17p13.3 deletions not involving LIS1. We show that the critical region that differentiates ILS from MDS at the molecular level can be reduced to 400 kb. Using somatic cell hybrids from selected patients, we have identified eight genes that are consistently deleted in patients classified as having MDS. In addition, deletion of the genes CRK and 14-3-3ɛ delineates patients with the most severe lissencephaly grade. On the basis of recent functional data and the creation of a mouse model suggesting a role for 14-3-3ɛ in cortical development, we suggest that deletion of one or both of these genes in combination with deletion of LIS1 may contribute to the more severe form of lissencephaly seen only in patients with MDS.
Abstract Pantothenate kinase-associated neurodegeneration (PKAN) disease is an autosomal recessive neurodegenerative disorder with iron storage in the brain due to PANK2 gene mutations. Brain ...magnetic resonance imaging (MRI) shows the typical “eye-of-the-tiger” sign. The aim of the present study was to describe clinical, MRI and molecular findings in a 26-year-old male with atypical PKAN disease in whom, brain MRI scans showed bilateral pallidal T2-hypointensity with a small central region of T2-hyperintensity, resembling the “eye-of-the-tiger” typical image. Genetic analysis identified two mutations in PANK2 : c.1561G>A and c.1663G>A, being the latter never described before. Due to limited phenotype–genotype correlation among patients with movement disorders, if “eye-of-the-tiger” brain MRI is present, PANK2 mutations investigation are needed to confirm PKAN disease.
BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) 677Crightwards arrowT polymorphism is heterogeneously distributed worldwide, with the highest and lowest frequencies of the T allele in Mexico ...and Africa, respectively, and a south-to-north gradient in Europe. Distribution of MTHFR 1298Arightwards arrowC is less well known. It has been hypothesized that 677T frequency could result in part from gene-nutrient interactions. OBJECTIVE: The objective was to compare the association of 677T and 1298C alleles with plasma concentrations of homocysteine, folate, and vitamin B-12 in geographical areas with contrasting 677T allele frequencies. DESIGN: Healthy young adults (n = 1277) were recruited in Mexico City, the West African countries of Bénin and Togo, France, and Sicily (Italy). Homocysteine, folate, and vitamin B-12 were measured in plasma, and MTHFR polymorphisms were measured in genomic DNA. RESULTS: Mexico City and Sicily reported the highest and Bénin and Togo reported the lowest plasma concentrations of folate. Mexico City had the highest 677T allele prevalence and the lowest influence of 677TT genotype on homocysteine, whereas the opposite was observed in Africa. The prevalence of the 1298C allele was lowest in the Mexicans and Africans and highest in the French. The percentage of the 677T genotype was significantly associated with the folate concentrations in 677CC carriers in a univariate analysis (R = 0.976; 95% CI: 0.797, 0.996; P < 0.0002) and in a multiple regression model that included homocysteine, vitamin B-12, and age (P = 0.0002). CONCLUSION: Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677Crightwards arrowT polymorphism and folate status that may confer a selective advantage of TT-homozygous genotype when dietary intake of folate is adequate, at least in the areas studied.
Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in folate metabolism. Folate deficiency has been related to several conditions, including neural tube defects (NTDs) and cardiovascular ...diseases. Hence, MTHFR genetic variants have been studied worldwide, particularly the C677T and A1298C. We genotyped the C677T and A1298C MTHFR polymorphisms in Mexican Amerindians (MAs), from the largest sample included in a genetic study (n = 2026, from 62 ethnic groups), and in a geographically-matched Mexican Mestizo population (MEZ, n = 638). The 677T allele was most frequent in Mexican individuals, particularly in MAs. The frequency of this allele in both MAs and MEZs was clearly enriched in the South region of the country, followed by the Central East and South East regions. In contrast, the frequency of the 1298C risk allele in Mexicans was one of the lowest in the world. Both in MAs and MEZs the variants 677T and 1298C displayed opposite allele frequency gradients from southern to northern Mexico. Our findings suggest that in Mestizos the 677T allele was derived from Amerindians while the 1298C allele was a European contribution. Some subgroups showed an allele frequency distribution that highlighted their genetic diversity. Notably, the distribution of the frequency of the 677T allele was consistent with that of the high incidence of NTDs reported in MEZ.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Neural tube defects (NTD) are highly prevalent in the Mexican population. According to data from the Registry and Epidemiological Surveillance of External Congenital Malformations (RYVEMCE), at least ...1 in 250 conceptions that reach 20 weeks of pregnancy or more has a NTD. This number is three to four times higher than that observed in other related ethnic groups. A common novel mutation (C677T) in the methylenetetrahydrofolate reductase (MTHFR) gene is considered an associated risk factor for NTD and other malformations. Studies in different populations agree that the prevalence of the homozygote for the mutated allele is higher in cases of NTD than in controls. In a meta-analysis recently published, the mean prevalence of the homozygote for the mutation was 9.2% for different groups of European controls and 16.4% in NTD cases from the same populations. This prompted us to investigate the frequency of the normal (C) and the mutant (T) alleles and the prevalence of the expected (CC, CT and TT) genotypes in 250 healthy Mexican women from different parts of the country. The proportion of CC (17.6%), CT (47.6%), and TT (34.8%) genotypes found, and the gene frequencies of 0.414 and 0.586% for the C and T alleles, respectively, confirmed the very high prevalence of the mutant allele and the TT genotype in the sample studied. Comparisons with studies done in Holland, Ireland, the United States, Japan, and other ethnic groups showed highly significant differences, with an average OR of 5.8 (95% Cl 3.4–10.3) for a Mexican being homozygous for the mutation. These findings may explain an important part of the high prevalence of NTD observed in our population.
To determine the prevalence at birth and type of congenital malformations (CM) in newborns of epileptic mothers (NEM) treated and not treated with anticonvulsants, the correlation anticonvulsant/CM ...and other developmental disorders.
Multicenter case-control study, in 166 live births NEM diagnosed in 21 501 newborns with CM and respective controls from the Registro y Vigilancia Epidemiológica de Malformaciones Congénitas (RYVEMCE).
The frequency of CM in NEM treated with anticonvulsants was higher (48.3%) than in NEM of untreated mothers (28.3%), (OR= 2.37 IC95% 1.08-5.40), p=0.03. CMs most frequently found were: spina bifida, limb reduction defects, cleft lip palate, microcephaly, anotia/microtia, hypospadias, polydactyly, cleft palate, anophthalmia/ microphthalmia and omphalocele. No differences among monotherapy and polytherapy were observed. Diphenyl-hydantoin, carbamazepine and valproic acid were the most frequently anticonvulsants used.
Our results show the teratogenicity of epilepsy by itself, the synergistic effect of some anticonvulsants, and the need of an appropriate periconceptional control of the disease and treatment.
Background: A 776C→G variant (dbSNP ID: rs1801198) in the transcobalamin gene (TCN2; MIM# 275350) decreases the cellular and plasma concentration of transcobalamin and thereby influences the cellular ...availability of vitamin B12. Objective: To evaluate the worldwide prevalence of this variant and its association with homocysteine plasma level. Methods: The study was performed in 1433 apparently healthy subjects, including Afro-Americans and Afro-Africans and in 251 Afro-Africans participants with severe malaria. Results: The frequencies of the 776G allele were the highest in China (0.607; 95% CI 0.554 to 0.659), low in West Africa (Bénin and Togo, 0.178; 0.154 to 0.206), and intermediate in France (0.445; 0.408 to 0.481), Italy (0.352; 0.299 to 0.409), Morocco (0.370; 0.300 to 0.447) and Mexico (0.374; 0.392 to 0.419). The 776G genotype was more frequent in Afro-Americans from New York (16.7; 8.4 to 30.7) and in Afro-African patients with severe malaria (6.0%; 95% CI 3.7 to 9.6) than in healthy Afro-African volunteers (p = 0.0004 and p = 0.033, respectively), while no difference was observed for MTHFR 677TT and 677T alleles. A disequilibrium of TCN2 genotype distribution was recorded in patients with severe malaria, with a twofold higher GG genotype than expected (p = 0.010). An association between the TCN2 polymorphism and homocysteine was observed only in Mexico and France, the two countries with the highest rate of low plasma concentration of vitamin B12 (<100 pmol/l). Conclusion: Given the dramatic heterogeneity of the 776G allele frequency worldwide, this polymorphism may be prone to a selective pressure or confers an evolutionary advantage in confronting environmental factors, one of which is malaria.
Severe congenital neutropenia type 4 (SCN4) is a rare autosomal recessive granulopoiesis disorder caused by
gene pathogenic variants. The estimated prevalence is 1/10,000,000 people. Over 90% of ...patients present a syndromic form with variable multisystemic involvement, including congenital heart defects, increased visibility of superficial veins (IVSV), inflammatory bowel disease, and congenital urogenital defects as prominent symptoms.
The objective of the study was to study non-hematological phenotypic findings that suggest a clinical diagnosis of SCN4.
We examined medical records of patients diagnosed with neutropenia from January 2000 to December 2020, selecting cases with non-hematologic manifestations for phenotypic description and
gene sequencing.
We found 11 cases with non-hematologic features: congenital heart defects in 8, IVSV in 6, inflammatory bowel disease in 4, urogenital defects in 4, and similar facial appearance. In addition, Sanger sequencing confirmed 3 homozygous cases for the c.210delC variant, a compound heterozygous harboring this variant, and a c.199_218+1 deletion.
Our findings of the c.210delC variant in very close geographical settings, to date, have only been reported among Mexicans, and a mutual uncommon surname in two families strongly supports a founder effect for the variant in the studied population. Furthermore, the described non-hematologic symptoms in patients with severe primary neutropenia should be explored, confirming SCN4 by investigating
gene mutations.
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