Update of variants identified in the pancreatic ß-cell KATP channel genes KCNJ11 and ABCC8 in individuals with congenital hyperinsulinism and diabetes.

The most common genetic cause of neonatal diabetes and hyperinsulinism is pathogenic variants in ABCC8 and KCNJ11. These genes encode the subunits of the ß-cell ATP-sensitive potassium channel, a key component of the glucose-stimulated insulin secretion pathway. Mutations in the two genes cause dysregulated insulin secretion; inactivating mutations cause an oversecretion of insulin, leading to congenital hyperinsulinism, whereas activating mutations cause the opposing phenotype, diabetes. This review focuses on variants identified in ABCC8 and KCNJ11, the phenotypic spectrum and the treatment implications for individuals with pathogenic variants.

Low bone mineral density and renal malformation in Mexican patients with Turner syndrome are associated with single nucleotide variants in vitamin D-metabolism genes.

Turner syndrome (TS) is a common genetic disorder. TS-phenotype includes short stature, gonadal dysgenesis, cardiac and kidney malformations, low bone mineral density (low-BMD) and thyroiditis. TS-phenotype varies from patient to patient and the cause is not clear, the genomic background may be an important contributor for this variability. Our aim was to identify the association of specific single nucleotide variants in the PTPN22, VDR, KL, and CYP27B1 genes and vitamin D-metabolism, heart malformation, renal malformation, thyroiditis, and low-BMD in 61 Mexican TS-patients. DNA samples were genotyped for SNVs: rs7975232 (VDR), rs9536282 (KL), rs4646536 (CYP27B1), and rs1599971 (PTPN22) using the KASP assay. Chi-square test under a recessive model and multifactorial dimensionality reduction method were used for analysis. We found a significant association between renal malformation and the rs9536282 (KL) variant and between rs4646536 (CYP27B1) and low-BMD, these variants may have modest effects on these characteristics but contribute to the variability of the TS phenotype. In addition, we identified gene-gene interactions between variants in genes KL, CYP27B1 and VDR related to vitamin D-metabolism and low-BMD in TS-patients. Our results support the idea that the genetic background of TS-patients contributes to the clinical variability seen in them.

Duplication of SOX9 associated with 46,XX ovotesticular disorder of sex development.

RESEARCH QUESTION: The purpose of the present study was to investigate whether ten unrelated SRY-negative individuals with this sex differentiation disorder presented a double dose of SOX9 as the cause of their disease. DESIGN: Ten unrelated SRY-negative 46,XX ovotesticular disorder of sexual development (DSD) subjects were molecularly studied. Multiplex-ligation dependent probe amplification (MLPA) and quantitative real-time PCR analysis (qRT-PCR) for SOX9 were performed. RESULTS: The MLPA analysis demonstrated that one patient presented a heterozygous duplication of the entire SOX9 coding region (above 1.3 value of peak ratio), as well as at least a ~ 483 kb upstream duplication. Moreover, no duplication of other SOX9 probes was observed corresponding to the region between -1007 and -1500 kb upstream. A qRT-PCR analysis showed a duplication of at least -581 kb upstream and ~1.63 kb of the coding region that encompasses exon 3. The limits of the duplication were mapped approximately from ~71539762 to 72122741 of Chr17. No molecular abnormalities were found in the remaining nine patients. CONCLUSION: This study is thought to be the first report regarding a duplication of SOX9 that is associated with the presence of 46,XX ovotesticular DSD, encompassing at least -581 kb upstream, and the almost entire coding region of the gene.

Aspartame Administration and Insulin Treatment Altered Brain Levels of CYP2E1 and CYP3A2 in Streptozotocin-Induced Diabetic Rats.

This study demonstrates that aspartame consumption and insulin treatment in a juvenile diabetic rat model leads to increase in cytochrome P450 (CYP) 2E1 and CYP3A2 isozymes in brain. Diabetes mellitus was induced in postweaned 21-day-old Wistar male rat by streptozotocin. Animals were randomly assigned to one of the following groups: untreated control, diabetic (D), D-insulin, D-aspartame, or the D-insulin + aspartame-treated group. Brain and liver tissue samples were used to analyze the activity of CYP2E1 and CYP3A2 and protein levels. Our results indicate that combined treatment with insulin and aspartame in juvenile diabetic rats significantly induced CYP2E1 in the cerebrum and cerebellum without modifying it in the liver, while CYP3A2 protein activity increased both in the brain and in the liver. The induction of CYP2E1 in the brain could have important in situ toxicological effects, given that this CYP isoform is capable of bioactivating various toxic substances. Additionally, CYP3A2 induction in the liver and brain could be considered a decisive factor in the variation of drug response and toxicity.

Ultrasonographic description of brain cortex and cingulate sulcus development in Mexican neonates and infants with congenital hypothyroidism.

BACKGROUND: Ultrasonography of cortical and cingulum maturity patterns, were studied in newborns and infants with congenital hypothyroidism (CH). METHOD: Transversal study of 29 newborns and infants with CH, detected by neonatal screening and confirmed with thyroid function test, thyroid ultrasonography, and thyroid scintigraphy. During the first 2 months of life, transfontanelar brain ultrasonography was performed. Brain cortex maturity was assessed by normality referents provided by Slagle and Timor methods. RESULTS: Cortical immaturity signs were observed in 69% of infants (20 patients with Slage's method brain cortex development delay (Pearson's p=0.05). Logistic nominal analysis for normality prediction demonstrated a correlation between brain cortex development and age, bone age, treatment duration, and type of CH. The most sensitive detecting technique was sagittal sight by Slagle's method. CONCLUSIONS: Brain cortex delayed development is frequent in children with CH. Bone age, postnatal age at treatment start, and time since treatment start, correlates with neurological development, but not athyreosis or sublingual nodule.

Latin American consensus: children born small for gestational age.

BACKGROUND: Children born small for gestational age (SGA) experience higher rates of morbidity and mortality than those born appropriate for gestational age. In Latin America, identification and optimal management of children born SGA is a critical issue. Leading experts in pediatric endocrinology throughout Latin America established working groups in order to discuss key challenges regarding the evaluation and management of children born SGA and ultimately develop a consensus statement. DISCUSSION: SGA is defined as a birth weight and/or birth length greater than 2 standard deviations (SD) below the population reference mean for gestational age. SGA refers to body size and implies length-weight reference data in a geographical population whose ethnicity is known and specific to this group. Ideally, each country/region within Latin America should establish its own standards and make relevant updates. SGA children should be evaluated with standardized measures by trained personnel every 3 months during year 1 and every 6 months during year 2. Those without catch-up growth within the first 6 months of life need further evaluation, as do children whose weight is ≤ -2 SD at age 2 years. Growth hormone treatment can begin in SGA children > 2 years with short stature (< -2.0 SD) and a growth velocity < 25th percentile for their age, and should continue until final height (a growth velocity below 2 cm/year or a bone age of > 14 years for girls and > 16 years for boys) is reached. Blood glucose, thyroid function, HbA1c, and insulin-like growth factor-1 (IGF-1) should be monitored once a year. Monitoring insulin changes from baseline and surrogates of insulin sensitivity is essential. Reduced fetal growth followed by excessive postnatal catch-up in height, and particularly in weight, should be closely monitored. In both sexes, gonadal function should be monitored especially during puberty. SUMMARY: Children born SGA should be carefully followed by a multidisciplinary group that includes perinatologists, pediatricians, nutritionists, and pediatric endocrinologists since 10% to 15% will continue to have weight and height deficiency through development and may benefit from growth hormone treatment. Standards/guidelines should be developed on a country/region basis throughout Latin America.

Protein-conformational diseases in childhood: Naturally-occurring hIAPP amyloid-oligomers and early ß-cell damage in obesity and diabetes.

BACKGROUND AND AIMS: This is the first time that obesity and diabetes mellitus (DM) as protein conformational diseases (PCD) are reported in children and they are typically diagnosed too late, when ß-cell damage is evident. Here we wanted to investigate the level of naturally-ocurring or real (not synthetic) oligomeric aggregates of the human islet amyloid polypeptide (hIAPP) that we called RIAO in sera of pediatric patients with obesity and diabetes. We aimed to reduce the gap between basic biomedical research, clinical practice-health decision making and to explore whether RIAO work as a potential biomarker of early ß-cell damage. MATERIALS AND METHODS: We performed a multicentric collaborative, cross-sectional, analytical, ambispective and blinded study; the RIAO from pretreated samples (PTS) of sera of 146 pediatric patients with obesity or DM and 16 healthy children, were isolated, measured by sound indirect ELISA with novel anti-hIAPP cytotoxic oligomers polyclonal antibody (MEX1). We carried out morphological and functional studied and cluster-clinical data driven analysis. RESULTS: We demonstrated by western blot, Transmission Electron Microscopy and cell viability experiments that RIAO circulate in the blood and can be measured by ELISA; are elevated in serum of childhood obesity and diabetes; are neurotoxics and works as biomarkers of early ß-cell failure. We explored the range of evidence-based medicine clusters that included the RIAO level, which allowed us to classify and stratify the obesity patients with high cardiometabolic risk. CONCLUSIONS: RIAO level increases as the number of complications rises; RIAOs > 3.35 µg/ml is a predictor of changes in the current indicators of ß-cell damage. We proposed a novel physio-pathological pathway and shows that PCD affect not only elderly patients but also children. Here we reduced the gap between basic biomedical research, clinical practice and health decision making.

Puberty blockade: Clinical guideline for the diagnosis and treatment of precocious puberty.

The Mexican Society of Pediatric Endocrinology developed a clinical practice guide for the diagnosis and treatment of precocious puberty. This document presents recommendations related to the interventions for the inhibition of central precocious puberty. The detailed description of the methodology for the development of this guide and the grading system, as well as the synthesis of the evidence on which it is based can be consulted in this same supplement.

La Sociedad Mexicana de Endocrinología Pediátrica elaboró una guía de práctica clínica para el diagnóstico y el tratamiento de la pubertad precoz. Este documento presenta recomendaciones relacionadas con las intervenciones para inhibir la pubertad precoz central. La descripción detallada de la metodología para el desarrollo de esta guía y del sistema de gradación, así como la síntesis de la evidencia en la que se basa, pueden consultarse en este mismo suplemento.

Diagnosis of precocious puberty: clinical guideline for the diagnosis and treatment of precocious puberty.

The Mexican Society of Pediatric Endocrinology developed a clinical practice guide for the diagnosis and treatment of precocious puberty. This document presents recommendations related to the diagnosis of precocious puberty. The detailed description of the methodology for the development of this guide and the grading system, as well as the synthesis of the evidence on which it is based can be accessed in this same supplement.

La Sociedad Mexicana de Endocrinología Pediátrica elaboró una guía de práctica clínica para el diagnóstico y el tratamiento de la pubertad precoz. Este documento presenta recomendaciones relacionadas con el diagnóstico de pubertad precoz. La descripción detallada de la metodología para el desarrollo de esta guía y del sistema de gradación, así como la síntesis de la evidencia en la que se basa, pueden consultarse en este suplemento.

Methodology for the development of the Clinical guideline for the diagnosis and treatment of precocious puberty.

Background: The Mexican Society of Pediatric Endocrinology presents recommendations for the diagnosis and treatment of precocious puberty (PP), a condition defined as the development of sexual characteristics due to an increase in pituitary gonadotropin secretion before 8 or 9 years of age in girls and boys, respectively. Methods: Three systematic reviews were conducted: controlled clinical trials on interventions for PP treatment, diagnostic tests, and observational studies on the long-term effects of PP. The quality evaluation and data extraction from the studies were conducted by two independent reviewers. The Scottish Intercollegiate Guidelines Network and the Oxford Center for Evidence-Based Medicine systems were used for grading the quality of evidence for recommendations on intervention and diagnosis, respectively. Recommendations were submitted to a consensus by a Delphi method and were validated by another 143 certified pediatric endocrinologists through an online questionnaire. Results: The group generated 12 recommendations on the diagnosis of PP, seven on the diagnosis of secondary causes of PP, eight on interventions for inhibition of puberty, five on other interventions for PP treatment, and 14 for the monitoring and follow-up of these patients. The online questionnaires submitted to certified pediatric endocrinologists showed more than 90% of approval for each one of the recommendations. Conclusions: Although a high degree of consensus for the recommendations for diagnosis, treatment, and monitoring of PP among pediatric endocrinologists was achieved, most of these recommendations showed a low level of evidence.

Introducción: La Sociedad Mexicana de Endocrinología Pediátrica presenta recomendaciones para el diagnóstico y el tratamiento de la pubertad precoz (PP), condición definida como el desarrollo de caracteres sexuales por incremento en la secreción hipofisiaria de gonadotropinas antes de los 8 años en las niñas y de los 9 años en los niños. Métodos: Se realizaron tres revisiones sistemáticas de ensayos clínicos controlados sobre intervenciones para el tratamiento de la PP, pruebas diagnósticas y estudios observacionales sobre efectos a largo plazo de la PP. La evaluación de la calidad de los estudios y la extracción de datos se realizó por pares. La evidencia se graduó con el sistema de la Scottish Intercollegiate Guidelines Network (SIGN) y del Oxford Centre for Evidence-Based Medicine (OCEBM) para las recomendaciones sobre la intervención y el diagnóstico, respectivamente. Las recomendaciones generadas se sometieron a un consenso por el método Delphi y fueron validadas por otros 143 endocrinólogos pediatras certificados mediante un cuestionario en línea. Resultados: Mediante consenso se generaron 12 recomendaciones para el diagnóstico de PP, siete sobre diagnóstico de causas secundarias de PP, ocho sobre intervenciones para inhibición de la pubertad, cinco sobre otras intervenciones en PP y 14 para la monitorización del tratamiento y el seguimiento de estos pacientes. Se obtuvo más del 90% de aprobación para cada una de las recomendaciones por el grupo de endocrinólogos certificados que respondieron el cuestionario en línea. Conclusiones: Si bien se logró un alto grado de consenso para las recomendaciones para el diagnóstico, el tratamiento y la monitorización de la PP entre los endocrinólogos pediatras, el nivel de evidencia para la mayoría de estas recomendaciones resultó bajo.

Diagnosis of secondary causes of precocious puberty: Clinical guideline for the diagnosis and treatment of precocious puberty.

The Mexican Society of Pediatric Endocrinology developed a clinical practice guide for the diagnosis and treatment of precocious puberty. This document presents recommendations related to the diagnosis of secondary causes of central PP. The detailed description of the methodology for the development of this guide and the grading system, as well as the synthesis of the evidence on which it is based can be consulted in this same supplement.

La Sociedad Mexicana de Endocrinología Pediátrica elaboró una guía de práctica clínica para el diagnóstico y el tratamiento de la pubertad precoz. Este documento presenta recomendaciones relacionadas con el diagnóstico de causas secundarias de pubertad precoz central. La descripción detallada de la metodología para el desarrollo de esta guía y del sistema de gradación, así como la síntesis de la evidencia en la que se basa, pueden consultarse en este mismo suplemento.

Adjuvant interventions in the treatment of precocious puberty: Clinical guideline for the diagnosis and treatment of precocious puberty.

The Mexican Society of Pediatric Endocrinology developed a clinical practice guide for the diagnosis and treatment of precocious puberty. This document presents recommendations related to the complementary interventions for the treatment of precocious puberty besides puberty blockade. The detailed description of the methodology for the development of this guide and the grading system, as well as the synthesis of the evidence on which it is based, can be consulted in this same supplement.

La Sociedad Mexicana de Endocrinología Pediátrica elaboró una guía de práctica clínica para el diagnóstico y el tratamiento de la pubertad precoz. Este documento presenta recomendaciones relacionadas con intervenciones adyuvantes en el tratamiento de la pubertad precoz distintas de la inhibición de la pubertad. La descripción detallada de la metodología para el desarrollo de esta guía y del sistema de gradación, así como la síntesis de la evidencia en la que se basa, pueden consultarse en este mismo suplemento.

Monitoring during the treatment of precocious puberty: Clinical guideline for the diagnosis and treatment of precocious puberty.

The Mexican Society of Pediatric Endocrinology developed a clinical practice guide for the diagnosis and treatment of precocious puberty. This document presents recommendations related to the monitorization of the treatment and follow-up of patients with central precocious puberty. The detailed description of the methodology for the development of this guide and the grading system, as well as the synthesis of the evidence on which it is based, can be consulted in this same supplement.

La Sociedad Mexicana de Endocrinología Pediátrica elaboró una guía de práctica clínica para el diagnóstico y el tratamiento de la pubertad precoz. Este documento presenta recomendaciones relacionadas con la monitorización del tratamiento y el seguimiento de pacientes con pubertad precoz central. La descripción detallada de la metodología para el desarrollo de esta guía y del sistema de gradación, así como la síntesis de la evidencia en la que se basa, pueden consultarse en este mismo suplemento.

Synthesis of the evidence: Clinical guideline for the diagnosis and treatment of precocious puberty.

Three systematic reviews were conducted to formulate the recommendations on diagnosis, treatment and follow-up of patients with precocious puberty: interventions for the treatment of precocious puberty that included the outcomes of final or near-final height, mental health, metabolic health, health bone, or blockade success; comparative observational studies evaluating long-term outcomes in subjects with a history of precocious puberty; and diagnostic test accuracy studies for puberty.

Se realizaron tres revisiones sistemáticas para la formulación de las recomendaciones sobre diagnóstico, tratamiento y seguimiento de pacientes con pubertad precoz: intervenciones para el tratamiento de la pubertad precoz que incluyeran los desenlaces de talla final o casi final, salud mental, salud metabólica, salud ósea o éxito en el bloqueo; estudios observacionales comparativos que evaluaran desenlaces a largo plazo en sujetos con antecedentes de pubertad precoz; y por último, estudios de exactitud de prueba diagnóstica para pubertad.

[Obesity and metabolic syndrome. A challenge for the Mexican Institutes of Health]. / La obesidad y el síndrome metabólico. Un reto para los Institutos Nacionales de Saluda.

Numerous efforts for the development of basic and clinical research in obesity are being made by the National Institutes of Health and Federal Reference Hospitals in Mexico. However, greater interaction among researchers and stronger efforts towards the dissemination of the results are needed. The document outlines the general ideas and proposals of the Academic Group for the Study, Prevention and Treatment of Obesity and Metabolic Syndrome of the Coordinating Committee of the National Institutes of Health and High Specialty Hospitals (CCINSHAE). This is the first step in developing common objectives, with the aim of understanding the effect of these entities in public health and to establish guidelines to limit and eventually overcome them. We discuss the appropriateness of analyzing obesity and the metabolic syndrome together, and the current management of these entities at the National Institutes of Health in Mexico. The problems that arise in clinical practice lead to the need to generate a new model of medical care, including a new health worker and a new patient. It is imperative to establish permanent lines of communication and education with health personnel and with patients. The group proposes an integrated approach for research in these areas. Finally, a master plan that links the National Institutes of Health, particularly in the areas of research and programs within the institutions, is required as a first step in seeking answers useful in solving the problem. The second step would be linking the first and second levels of care through concrete actions needed to limit and reduce obesity and metabolic syndrome in the population.

Unpacking the aggregation-oligomerization-fibrillization process of naturally-occurring hIAPP amyloid oligomers isolated directly from sera of children with obesity or diabetes mellitus.

The formation of amyloid oligomers and fibrils of the human islet amyloid polypeptide (hIAPP) has been linked with ß- cell failure and death which causes the onset, progression, and comorbidities of diabetes. We begin to unpack the aggregation-oligomerization-fibrillization process of these oligomers taken from sera of pediatric patients. The naturally occurring or real hIAPP (not synthetic) amyloid oligomers (RIAO) were successfully isolated, we demonstrated the presence of homo (dodecamers, hexamers, and trimers) and hetero-RIAO, as well as several biophysical characterizations which allow us to learn from the real phenomenon taking place. We found that the aggregation/oligomerization process is active in the sera and showed that it happens very fast. The RIAO can form fibers and react with anti-hIAPP and anti-amyloid oligomers antibodies. Our results opens the epistemic horizon and reveal real differences between the four groups (Controls vs obesity, T1DM or T2DM) accelerating the process of understanding and discovering novel and more efficient prevention, diagnostic, transmission and therapeutic pathways.

Economic family burden of metabolic control in children and adolescents with type 1 diabetes mellitus.

AIM: To appraise the economic burden for families of patients with type 1 diabetes mellitus (DM1) at the Instituto Nacional de Pediatria in Mexico City. PATIENTS AND METHODS: DM1 family direct costs were obtained from a standardized economic survey in 59 children with no chronic severe complications such as kidney failure in 2002-3. RESULTS: Mean family annual direct cost of treatment and monitoring was US $1689.87 which includes government funding given to both outpatients and inpatients. Despite this, DM1 out-of-pocket cost for families is very high compared to the minimum official wage of approximately $4.00 dollar/day versus $4.06 cost DM1/day. No correlation between parents' age, education or socio-economic level and direct cost was statistically significant. CONCLUSIONS: The highest economic burden was due to self-monitoring of blood glucose (SMBG) 53.0% and insulin 14.8%. The costs were higher in children with poor metabolic control who performed SMBG less often.

[How safe is the recombinant human growth hormone?] / ¿Qué tan segura es la hormona de crecimiento humana recombinante?

In this paper, several aspects related to the safety of the use of biosynthetic human growth hormone are reviewed. For example, its classification as a biosynthetic drug, the phases that need to be performed in Mexico to verify its safety (obtaining, purification, preclinical studies, clinical trials, and finally observational clinical studies), as well as the evidence that exists in relation to the association of intracranial hypertension, muscular events, scoliosis, slipped capital femoral epiphysis, obstructive sleep apnea, pancreatitis, alterations in cortisol, thyroid hormones alterations, cardiovascular disease, metabolic risk, mortality and cancer, adverse events not related to its use, and finally dosing and safety.

Se revisan diferentes aspectos relacionados con la seguridad del uso de la hormona de crecimiento humana recombinante en niños, tales como su tipificación como un medicamento biosintético, las fases que es necesario realizar en nuestro país para verificar su seguridad (obtención, purificación, etapa preclínica, estudios clínicos experimentales y finalmente estudios clínicos observacionales) y se expone la evidencia que existe en relación con la asociación de hipertensión intracraneana, eventos musculares, escoliosis, deslizamiento de la cabeza femoral, apnea obstructiva del sueño, pancreatitis, alteraciones en cortisol, modificaciones de las hormonas tiroideas, enfermedad cardiovascular, riesgo metabólico, mortalidad y cáncer, eventos adversos no relacionados con su uso, y finalmente dosificación y seguridad.

[Use of recombinant Human Growth Hormone (rHGH)]. / Uso de hormona de crecimiento humana recombinante (HChr).

Recombinant human growth hormone, synthesized in E.coli or mammalian cells cultures, is since 1985, a useful therapeutic resource to increase growth velocity and final height. In this paper are discussed the four phases (aims, security and efficacy, utility and efficiency) indispensables to define the start of treatment, as well as the absolute, relative and metabolic indications and the transitory and permanent conditions that contraindicate its use. It is commented the way to optimize the results (simple but indispensables indications for the physician, the patients and their family). Finally it is analyzed the results of treatment in patients with growth hormone deficiency, Turner syndrome, chronic renal failure, Prader-Willi syndrome, Noonan syndrome, SHOX deficiency, intrauterine growth retardation and idiopathic short stature.

La hormona de crecimiento humana obtenida por técnicas de DNA recombinante en cultivos de E. coli o de células de mamífero, es un medicamento biotecnológico que desde 1985 permite mejorar la velocidad de crecimiento y la estatura final. En este artículo se comentan las cuatro etapas (objetivos, seguridad y eficacia, utilidad y eficiencia) que son necesarias para definir el inicio del tratamiento, así como las indicaciones absolutas, relativas y metabólicas, así como las condiciones temporales y permanentes que la contraindican. También se señala cómo optimizar el resultado al seguir indicaciones sencillas pero indispensables que deben ser trasmitidas al paciente y a su familia de manera simple y clara pero categórica. Se muestran los resultados del uso de hormona de crecimiento en pacientes con deficiencia de hormona de crecimiento, síndrome de Turner, insuficiencia renal crónica, síndrome de Prader-Willi, síndrome de Noonan, deficiencia de SHOX, retraso de crecimiento intrauterino y talla baja idiopática.

Mutations in MODY genes are not common cause of early-onset type 2 diabetes in Mexican families.

CONTEXT: Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes mellitus characterized by autosomal dominant inheritance, early age of onset and a primary insulin secretion defect. Certain MODY gene sequence variants may be involved in polygenic forms of type 2 diabetes. OBJECTIVE: We assessed the contribution of MODY genes to the etiology of type 2 early-onset diabetes in 23 Mexican families, including five with apparently autosomal dominant inheritance. PATIENTS: Twenty-three unrelated Mexican families with early-onset type 2 diabetes previously screened for the presence of glucokinase mutations, were studied. DESIGN: We screened MODY genes for sequence variants by PCR-SSCP analysis and automated sequencing. We performed a functional analysis of the HNF-1alpha P379H recombinant protein in vitro in both HeLa and RINm5f beta-cell lines. MAIN OUTCOME MEASURES: MODY gene mutation screening and P379H mutant protein transactivation assay. RESULTS: No mutations were detected in the HNF-4alpha, IPF-1, NEUROD1 or HNF-1beta genes in any of the families studied. A new mutation (P379H) of the HNF-1alpha gene was identified in one MODY family. RINm5f and HeLa cell transfection assays revealed decreased transactivation activity of the mutant protein on the human insulin promoter. CONCLUSIONS: All known MODY genes were screened for abnormalities in this cohort of early-onset diabetes families which included 5 MODY pedigrees. We identified a new HNF-1alpha MODY mutation (P379H) and demonstrated that it reduces the transactivation potential of the mutant protein on the human insulin promoter. No other mutation was identified in this cohort indicating that abnormalities in MODY genes are generally not a common cause of early-onset diabetes and this includes MODY families in Mexico.