Rosa Pardo

Wheat flour fortification with folic acid: Changes in neural tube defects rates in Chile†

In January 2000, Chilean Ministry of Health mandated the addition of folic acid (FA) to wheat flour in order to reduce the risk of neural tube defects (NTDs). This policy resulted in significant increases in serum and red cell folate in women of fertile age 1 year after fortification. To evaluate the effect of wheat flour fortification on the prevalence of NTDs in Chile we designed a prospective hospital‐based surveillance program to monitor the frequency of NTDs in all births (live and stillbirths) with birth weight ≥500 g at the nine public maternity hospitals of Santiago, Chile from 1999 to 2009. During the pre‐fortification period (1999–2000) the NTD rate was 17.1/10,000 births in a total of 120,566 newborns. During the post‐fortification period (2001–2009) the NTD rate decreased to 8.6/10,000 births in a total of 489,915 newborns, which translates into a rate reduction of 50% (RR: 0.5; 95% CI: 0.42–0.59) for all NTDs. The rate reduction by type of NTD studied was: 50% in anencephaly (RR: 0.5; 95% CI: 0.38–0.67), 42% in cephalocele (RR: 0.58; 95% CI: 0.37–0.89), and 52% in spina bifida (RR: 0.48; 95% CI: 0.38–0.6). Rates showed significant reduction both in stillbirths and live births: 510.3 to 183.6/10,000 (RR = 0.36; 95% CI: 0.25–0.53) and 13.3 to 7.5/10,000 (RR = 0.56; 95% CI: 0.47–0.68), respectively. In Chile, fortification of wheat flour with FA has proven to be an effective strategy for the primary prevention of NTDs.

Prevalencia al nacimiento de malformaciones congénitas y de menor peso de nacimiento en hijos de madres adolescentes

:The births occurred in a hospital between 1982 and 2001, were analyzed using the Latin Amer-ican Collaborative Study for Congenital Malformations (ECLAMC) data base. Mothers were clas-sified as teenagers when their age ranged between 10 and 19 years old and older when their agewas over 20 years old. All women were subdivided as cases and controls.

Caracterización clínico-genético-molecular de 45 pacientes chilenos con Síndrome de Prader Willi

Background: Prader-Willi syndrome (PWS) is a neurogenetic disease characterized by neonatal hypotonia, retarded mental and motor development, hypogonadism, hyperphagia, morbid obesity and dysmorphic facial features. It has an incidence of 1:12.000-15.000 newborns and is caused by abnormalities in genes located in 15q11q13. PWS is one of the most frequent genetic disorders and microdeletion syndromes. It is also the most common cause of obesity from genetic origin and it was the first disease in which imprinting and uniparental disomy were recognized as cause of genetic disorders. Seventy to seventy five percent of PWS cases are due to 15q11q13 deletions, 20-25% to uniparental disomy and 1% to mutations in the imprinting center. Aim: To analyze the clinical, genetic and molecular features of patients with PWS, seen at one institution. Patients and methods: Retrospective review of 45 patients (27 males) with PWS seen at the Genetics Outpatient Clinic at INTA. Results: Twenty three (51.1%) patients had a delection, 13 (28.9%) patients did not have a deletion. In nine patients, fluorescence in situ hybridization (FISH) study was not performed, therefore the presence of deletion was unknown. The clinical score was 8 points for patients younger than 3 years (n=11) and 11.5 points for patients older than 3 years (n=34); for patients aged 12 months or less, the clinical score was 7 points. Mean clinical score was 11 points for patients with deletion and 10 points for patients without deletion. Conclusions: Most patients with PWS have a deletion; the phenotype depends on age and the clinical score is useful for Chilean patients with PWS (Rev Med Chile 2005; 133: 33-41).

Family-Based Association Study Between SLC2A1, HK1, and LEPR Polymorphisms With Myelomeningocele in Chile

Obese/diabetic mothers present a higher risk to develop offspring with myelomeningocele (MM), evidence supporting the role of energy homeostasis-related genes in neural tube defects. Using polymerase chain reaction–restriction fragment length polymorphism, we have genotyped SLC2A1, HK1, and LEPR single-nucleotide polymorphisms in 105 Chilean patients with MM and their parents in order to evaluate allele–phenotype associations by means of allele/haplotype transmission test (TDT) and parent-of-origin effects. We detected an undertransmission for the SLC2A1 haplotype T-A (rs710218-rs2229682; P = .040), which was not significant when only lower MM (90% of the cases) was analyzed. In addition, the leptin receptor rs1137100 G allele showed a significant increase in the risk of MM for maternal-derived alleles in the whole sample (2.43-fold; P = .038) and in lower MM (3.20-fold; P = .014). Our results support the role of genes involved in energy homeostasis in the risk of developing MM, thus sustaining the hypothesis of diverse pathways and genetic mechanisms acting in the expression of such birth defect.

Estudio genético de una familia chilena con tres fenotipos dentales diferentes

Background: Congenital dental anomalies can affect up to 25% of the population. Aim: To report the genetic study of a family with dental anomalies. Material and methods: We studied a Chilean family presenting with three independent dental phenotypes: third molar agenesis, supernumerary teeth, and dentinal dysplasia type I. We searched for mutations in candidate genes proposed for tooth agenesis and supernumerary teeth: IRF6, FGFR1, MSX1, MSX2, PAX9, PRDM16 and TGFA. We also studied DSPP as a candidate gene for dentinal dysplasia type I. Results: We did not find mutations in FGFR1, MSX2, PAX9, PRDM16, or TGFA. We found a MSX1 mutation (G16D) in both affected and unaffected family members. Also, we found a genetic variation not described before in IRF6 in the dentinal dysplasia type I case. Conclusions: Further investigation is necessary to evaluate if these variants are functional in nature. Finally, we are reporting a mutation in DSPP in an asymptomatic 2-year-old child, which illustrates the ethical pitfalls of interpreting molecular data for genetic counseling of young and/or

Maternal biomarkers of methylation status and non-syndromic orofacial cleft risk: a meta-analysis

Animal models have shown evidence of the role of maternal methyl donor status and its metabolism (one-carbon metabolism) in normal embryonic maxillofacial development. Nevertheless, studies in humans have shown conflicting results for the association of maternal methylation status biomarkers in the aetiology of the main craniofacial birth defects: non-syndromic orofacial clefts (NSOFCs). The aim of this study was to perform a meta-analysis assessing the relationship between maternal levels of methylation status biomarkers (plasma and erythrocyte folates and plasma vitamin B12 and homocysteine) and the risk of NSOFCs. A literature search of the conventional and grey medical-scientific databases identified 12 studies considering these variables. Based on standardized differences between means among cases and controls (Cohens d test), evidence was found of an association only with high plasma homocysteine (d=0.37; P=0.026) when single effects were pooled. In addition to its usefulness as a marker of poor methyl-donor intake and/or metabolism, homocysteine appears to have a teratogenic effect. Although the results are based on a relatively small number of reports and/or studies of small sample sizes showing between-study heterogeneity, these problems were resolved by including an additional analysis. Therefore these findings constitute a real contribution towards explaining the complex aetiology of orofacial clefts.

Conocimiento sobre el ácido fólico en la prevención de defectos de cierre del tubo neural: una encuesta a mujeres que viven en Santiago de Chile

Background: Wheat flour in Chile is fortified with folic acid and pregnant women are also supplemented with the vitamin, but the population level of knowledge or awareness about this vitamin and its use by pregnant women is unknown. Aim: To assess the level of knowledge that postpartum women from Santiago de Chile have about folic acid. Material and methods: A questionnaire about folic acid and its efects on the prevention of neural tube defects was developed adapting questionnaires designed abroad. It was applied by medical students to puerperal women, hospitalized in public hospitals. Results: The questionnaire was applied to 342 women aged 26 ± 7 years. Sixty one percent were housewives and 55% completed high school education. Forty seven percent of these women had heard about folic acid, 9.6% knew that it was able to prevent congenital defects and only one received an adequate supplementation during pregnancy. Women aged 25 to 34 years and those with an adequate medical care during pregnancy had a significantly better knowledge about folic acid and its role in the prevention of congenital anormalies. The more commom means to receive information about folic acid were midwifes (34%), mass media (28%) and doctors (20%). Two hundred eleven women (62%) agreed to take folic acid in a future gestation and 58% preferred to do so using fortified foods. Conclusions: Post partum women from Santiago have a poor knowledge about the relevance of folic acid supplementation (Rev Med Chile 2007; 135; 1551-7). (Key words: Abnormalities; Folic acid; Nervous system malformations)

Quiste ovárico fetal: diagnóstico ecográfico prenatal. Evolución y tratamiento postnatal. Casos clínicos

Ovarian cysts are found in 32% of necropsies performed to neonates. They can also be diagnosed during gestation by ultrasonography. The clinical evolution of these cysts is variable, but in most cases the prognosis is favorable. Some complications such as ovarian torsion, bleeding, rupture and peritonitis have been described. We report two newborn girls with ovarian cysts, diagnosed during gestation. One required an emergency operation due to vomiting and abdominal distension, interpreted as a possible torsion of the cyst. The second girl was operated at the fourth day of life, finding a left ovarian cyst with torsion of the pedicle. Both girls had a favorable postoperative evolution (Rev Med Chile 2003; 131: 665-668)

Estudio de asociación de base familiar entre polimorfismos de MTHFR y mielomeningocele en Chile

Background: Mandatory fortification with folic acid (FA) was implemented in Chile in 2000. Thereafter, the rate of spina bifida decreased by 52 to 55%. Genetic abnormalities in folate metabolism may be involved in the etiology of spina bifida. Aim: To evaluate the association between myelomeningocele (MM) and c.A1298C and c.C677T polymorphisms within the coding gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) in the Chilean population. Material and Methods: These polymorphisms were genotyped in 105 patients showing isolated MM, born after the onset of FA fortification, and in their parents. The transmission disequilibrium test (TDT) was performed to evaluate alterations in the transmission of both alleles and haplotypes MTHFR polymorphism. We also evaluated the presence of parent-origin-effect (POE) of alleles using the Clayton’s extension of the TDT. Results: TDT analysis showed no significant distortions in the transmission of alleles or haplotypes. Moreover, although the POE showed increased risk for maternally derived allele, this risk was not statistically significant. Conclusions: The studied variants in the MTHFR gene (c.C677T and c.A1298C) do not constitute risk factors for MM in this sample of Chilean patients and their parents.BACKGROUND Mandatory fortification with folic acid (FA) was implemented in Chile in 2000. Thereafter, the rate of spina bifida decreased by 52 to 55%. Genetic abnormalities in folate metabolism may be involved in the etiology of spina bifida. AIM To evaluate the association between myelomeningocele (MM) and c.A1298C and c.C677T polymorphisms within the coding gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) in the Chilean population. MATERIAL AND METHODS These polymorphisms were genotyped in 105 patients showing isolated MM, born after the onset of FA fortification, and in their parents. The transmission disequilibrium test (TDT) was performed to evaluate alterations in the transmission of both alleles and haplotypes MTHFR polymorphism. We also evaluated the presence of parent-origin-effect (POE) of alleles using the Claytons extension of the TDT. RESULTS TDT analysis showed no significant distortions in the transmission of alleles or haplotypes. Moreover, although the POE showed increased risk for maternally derived allele, this risk was not statistically significant. CONCLUSIONS The studied variants in the MTHFR gene (c.C677T and c.A1298C) do not constitute risk factors for MM in this sample of Chilean patients and their parents.

Genética de la sordera congénita

Congenital deafness is defined as the hearing loss which is present at birth and, consequently, before speech development. It is the most prevalent sensor neural disorder in developed countries, and its incidence is estimated between 1-3 children per 1,000 newborns, of which more than 50% are attributable to genetics causes. Deafness can be classified as syndromic or non-syndromic. In the first case, it is associated with outer ear malformations and/or systemic findings. More than 400 syndromes accompanied of deafness have been described, which represent about 30% of cases of congenital hearing loss. The remaining percentage corresponds to non-syndromic cases: 75-85% are autosomal recessive, 15-24% are autosomal dominant, and 1-2% are X-linked. The evaluation of a child with deafness requires a multidisciplinary collaboration among specialists, who must coordinate themselves and give information to the affected family. The aims of establishing a diagnosis are to predict other manifestations that may suggest some syndrome and to anticipate their management, as well as to perform genetic counseling to parents and affected individuals.