Asociación entre marcadores moleculares localizados en 4q y fisura labiopalatina no sindrómica en población chilena / Association between molecular markers located in 4q and fissure labiopalatina not sindrómica in Chilean population

El objetivo de la presente investigación fue probar la posible asociación de uno o más microsatélites localizados en 4q25-4q33 y FLPNS. Se analizó una muestra de 51 genealogías extensas. A partir de estas genealogías se obtuvieron 51 tríos caso-progenitores, que se estudiaron con el programa extended transmisión disequilibrium test (ETDT). Además se colectó a 51 probandos y 94 controles para un estudio caso-control en población chilena y se postuló comprobar las diferencias entre ambos estudios de asociación. Se analizaron los microsatélites D4S1570, D4S1615, FGA, UCP1 y D4S1597 ubicados en 4q, utilizándose la técnica de la polimerasa en cadena (PCR) para el análisis de ADN, marcandose la hebra líder con un fluorocromo. Los resultados electroforeticos fueron analizados en un secuenciador automático ABIPRISM 377. Observándose que FGA en el grupo control y FGA, D4S1570 y D4S1597 en los pacientes estaban en equilibrio de H-W. Estos resultados implican que un estudio caso-control no es adecuado para el estudio de estos marcadores. Para obviar este problema se utilizó el programa ETDT, observándose que los microsatélites D4S1570, UCP1 y D4S1597 presentaron una asociación tipo alélica en familias multiples. Estos resultados sugiere que estos microsatélites se encontrarían cerca de 1 o más genes candidatos de esta malformación en la región eq24-4q31.

The objective of this investigation is to test the hypothesis of the possible association of one or more microsatellites located on 4q25-4q33 with NSCLP. In this study a sample of 51 extended pedigrees were analyzed. From these pedigrees a sample of 51 case-parents trios was obtained. A novel genetic analysis was carried out using the Extended Transmission Disequilibrium Test (ETDT). Also a case control study was carried out with the 51 probands of the case-parents trios plus a sample of 94 controls of the Chilean population to test if differences were observed resulting from the methods used for the association studies. Microsatellites D4S1570, D4S1615, FGA, UCPI and D4S1597 located in 4q were analyzed. The polymerase chain reaction (PCR) was used for analysis of DNA. Forward primers were marked with fluorescent-dye-Iabel. Electrophoresis and analyses were carried out in an ABI PRISM 377 automatic sequencer. In the case-control study, only FGA was in H-W equilibrium in controls, whereas FGA, D4S1570 y D4S1597 were in H-W equilibrium in cases. These results imply that a case control study does not represent an adequate procedure to carry out an association study between the aforementioned micro satellites and NSCLP. In order to obviate this problem the ETDT program was used. From all of the analyzed microsatellites, D4S1570, UCPl and D4S 1597 presented significant allele wise association in those case-parents trios to multiplex families. This result suggests that these microsatellites would be located close to one or more candidate genes for this malformation in 4q24-4q31.

Frecuencia de la mutación 185delAG en el gen BRCA1 en mujeres chilenas sanas con antecedentes familiares de cáncer de mama / Frequency of the 185delAG mutation in the BRCA1 gene in chilean healthy women with family history of breast cancer

Background: Breast cancer is the most common malignancy among women, and is the second cause of cancer mortality among Chilean women. Female mortality due to breast cancer in Chile has shown a steady increase from 9.5 deaths per 100.000 women in 1985 to 12.8 deaths per 100.000 in 1995. A family history of breast cancer is one of the main risk factors for the development of the disease. BRCA1 and BRCA2 are two major hereditary breast cancer susceptibility genes. Mutations in these genes are associated to inherited breast cancer; 664 predisposing mutations have been described, but in specific populations only some of them, such as 185delAG have been found to be associated with susceptibility to breast cancer. Aim: To establish the frequency of the 185delAG mutation in the BRCA1 gene in Chilean healthy women with a family history of breast cancer. Patients and Methods: The 185delAG mutation was studied by mismatch polymerase chain (PCR) reaction in 382 Chilean healthy women with at least two relatives affected with breast cancer. The PCR products were digested with the restriction enzyme HinfI. Digestion of the normal allele (170 pb fragment) produces a 150 pb fragment; the PCR product for the mutant allele does not contain a site for HinfI and therefore remains as a 170 bp fragment after digestion. Results: One of the 382 healthy women presented the fragment of 170 pb after digestion with HinfI suggesting that she was heterozygous carrier for this mutation. The mutant patient had a mammography without suspicion of cancer. Conclusions: The frequency of the 185delAG mutation in BRCA1 was 0.26 percent (1/382) in Chilean healthy women with a family history of breast cancer

Asociación entre el fenotipo fisura labiopalatina no sindrómica y marcadores de microsatélites ubicados en 6p, 17q y 19q / Association study of the nonsyndromic cleft lip/palate phenotype and microsatellite markers located in 6p, 17q and 19q

Background: In the search of the major genes responsible for the genetic etiology of Nonsyndromic Cleft Lip and Palate (NSCLP), an association study between this malformation and four molecular markers, F13A1 and EDN1 (6p), D17S579 (17q) and BCL3 (19q), was done. Aim: To determine, in a Chilean population, the presence of NSCLP susceptibility regions, as proposed for Caucasian populations in the 6p, 17q and 19q chromosomal regions. Material and Methods: A sample of unrelated NSCLP patients, that belonged to Simplex (Sx) and Multiplex (Mx) families, was analyzed. Blood donors were used as a control group (Co). The DNA of the four markers was amplified by means of PCR, their products analyzed by PAGE denaturants and visualized by silver staining. Statistical analysis was performed using c2 log ratio. Results: Allele frequency distribution of D17S579 was significantly different in all patients with NSCLP and their subgroups, when compared to control subjects. Significant differences in EDN1 frecuency were observed between the total groups of NSCLP patients and those pertaining to the Mx subgroup, when compared to controls. Differences in F13A1 distribution were only observed between NSCLP-Mx patients and controls. There was a slight difference in BCL3 distribution, between the total sample of NSCLP patients and controls. Conclusions: Our results support the hypothesis of the existence of cleft susceptibility regions in 6p and 17q. The small significance of BCL3, suggests that ethnicity can influence the interactions between involved genes

Recurrencia familiar del labio leporino con o sin fisura velopalatina de origen no sindrómico en poblaciones de Chile / Familial recurence of non syndromic cleft lip with or without cleft palate in Chilean populations

Background: The presence of major genes in the susceptibility of non syndromic cleft lip with or without cleft palate (CL/P) in Chile has been postulated, considering the high prevalence and familial aggregation of this condition. Aim: To study the familial recurrence of CL/P in Chile. Patients and methods: The recurrence risk of CL/P was studied in 217 extended pedigrees where 33 (15.2 percent) were multiplex (21 male and 12 female propositi). These multiplex extended pedigrees (with more than one affected individual) represented 75 nuclear pedigrees, constituted by 840 males and 803 females and are the basic information of this study. Results: A significantly higher frequency of affected males (4.15 percent) than affected females (2.27 percent) was observed, independent of the difference in number of propositi by sex. Even though no differences were observed between families where both parents were unaffected, compared to those with only one affected parent, a higher proportion of affected descendants was found when the affected propositi was the mother. In multiplex families, the recurrence risk, according to the genetic proximity to the proband, was 10.1, 3.6 and 3.3 percent respectively for first, second and third degree relatives. The figures were 1.5, 0.5 and 0.4 percent respectively, when adjusted to the 217 extended pedigrees. Considering that the risk for the general population in Chile is approximately 0.16 percent, it is 10.3, 3.2 and 2.6 times higher among affected families. Conclusions: The high heritability of CL/P and the risk encountered for the Chilean population supports the hypothesis of major genes involved in its susceptibility

Asociación entre el fenotipo fisura labiopalatina no sindrómica y marcadores de microsatélite ubicados en 4q / Association between nonsyndromic cleft lip/palate with microsatellite markers located in 4q

Background: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common craniofacial defect. Association studies have suggested that a cleftinglocus is located on chromosome 4q at or near two microsatellite markers D4S175 and D4S192. Aim: To test the hypothesis on the possible presence of a clefting locus on chromosome 4q. Material and methods: We carried out an association study on a sample of unrelated NSCLP patients, of their unaffected relatives and in controls. Both probands and relatives were further analyzed depending if they originated from simplex or multiplex families. DNA was analyzed with two PCR markers close to the putative NSCLP locus, dinucleotide repeats D4S175 and D4S192. PCR products were resolved by PAGE and visualized by silver staining. Statistical analysis was performed by means of c2 log ratio. Results: Significant differences between NSCLP and controls were observed when comparing the allele frequency distribution of D4S192 both in the total sample as well as in NSCLP-multiplex and simplex cases. No significant differences for D4S175 were observed in any of the comparisons. Unaffected relatives showed significant differences with controls both for D4S175 and D4S192. Conclusions: Our results support the hypothesis that a NSCLP locus maps on chromosome 4q close to the microsatellite marker D4S192. No differences were observed between NSCLP multiplex and simplex cases versus controls, implying that they do not represent different etiologic entities. The results of the present and previous studies in the same group of patients support the hypothesis that several major interacting genes participate in the etiology of NSCLP

Estudio de asociación entre la fisura labiopalatina no sindrómica y marcadores de microsatélite ubicados en 6p / Association study between non syndromic cleft lip palate and microsatellite markers located in 6p

Background: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common craniofacial developmental defect. Association studies have suggested that a clefting locus is located on chromosome 6p at or near two possible loci, Factor 13A (FI3A) in the region 6p 25-24 and HLA at 6p 21.3. Aim. To test the hypothesis on the possible presence of a major gene on chromosome 6p associated with NSCLP. Patients and methods: We carried out an association study on a sample of unrelated NSCLP patients from multiplex (Mx) and simplex (Sx) families, of their unaffected relatives and in control individuals. DNA was analyzed with three PCR markers close to the putative NSCLP locus, dinucleotide repeats at loci D6S89, D6S109 and D6S105. PCR products were resolved by PAGE and visualized by silver staining. Statistical analysis was performed by means of c2 log ratio. Results: Significant differences were observed when comparing the allele frequency distribution of D6S89 in patients with NSCLP and controls and in patients with NSCLP-Mx and controls. No significant differences were observed for patients with NSCLP-Sx. D6S109 and D6S105 showed no significant differences in any of the comparisons. Conclusions: Our results support the hypothesis that a NSCLP locus maps on 6p23 very close to D6S89. Results for D6S109 and D6S105 do not show a clear association. Differences observed between NSCLP-MX and Sx families seem to represent different etiologic entities. The results of the present study, plus those already published for candidate loci, TGFA and MSX1, support the hypothesis that several interacting major genes participate in the etiology of NSCLP

Pesquisa molecular y clínica del síndrome de X-frágil en 300 pacientes con retardo mental inespecífico / Clinical and metabolic screening for fragile X syndrome in 300 patients with unspecific mental retardation

Background: Fragile X syndrome is the most freqent cause of mental retardation linked to the X chromosome. In the majority of cases, the mutation responsible for the syndrome is an expansion of the trinucleotide repeat (CGG)n, present in the 5' region of exon 1 of the gene for mental retardation associated with fragile X syndrome (FMR-1). Aim: To report the results of a fragile X screening in patients with mental retardation. Patients and methods: Fragile X screening using polymerase chain reaction methods was done in 386 X chromosomes from 300 patients (214 male), aged 4 to 26 years old. The modified Hagerman test was applied to male patients. Hybridization techniques were applied in a subgroup of 51 patients. Results: (CGG)n 30 was the allele found with the highest frequency in 50.2percent of patients. (CGG)n 29 was found in 29percent of patients. One subject had an allele with 46 CGG repeats, which corresponds to the gray zone. Hybridization studies were highly concordant with PCR, detecting four males with fragile X syndrome and a carrier female. The average clinical score of mental retardation not due to fragile X syndrome was 10.3 ñ 3.4 (range 3 to 23), and 97percent of males had a score below 19. The concordance between scores over 20 and molecular genotype was 98percent. Conclusions: The distribution of (CGG)n repeats, observed in this study, was significantly different to that previously reported for a normal Chilean population. The dispersion of molecular status and clinical score was lower than previously described using cytogenetic techniques

La variación genética de MSX1 presenta un dimorfismo sexual en la fisura labiopalatina no sindrómica en la población chilena / Genetic variation of MSX1 has a sexual dimorphism in non syndromic cleft palate in the Chilean population

Background: Recent studies in mice have demonstrated that the Msx-1 homebox gene is implicated in cleft palate. Thus, it has been suggested that its human homologue, MSX1 (HOX-7), located in chromosome 4 could be involved in the etiology of non syndromic cleft lip palate. Aim: To study the linkage between non syndromic cleft palate and variations of MSX1 gene. Patients and methods: Seventy three patients with non syndromic cleft lip palate (34 simplex and 37 multiplex), 127 unaffected relatives of the cases (61 relatives of simplex cases and 66 relatives of multiplex cases) and 77 controls were studied. DNA was extracted from leukocytes and the intragenic microsatellite sequence was amplified by PCR. Results: A polymorphism of four alleles was observed, 1 (175 bp), 2 (173 bp), 3 (171 bp) and 4 (169 bp). Alleles 2 and 4 showed a joint variation in males with multiplex cleft lip palate and in their respective unaffected male relatives, that was significant when compared with male controls. Instead, the joint variation of alleles 1 and 4 of unaffected female relatives had significant differences with female controls. Females with multiplex cleft lip palate differed from female controls only in allele 1. Conclusions: These results support the hypothesis of a genetic heterogeneity in the etiology of non syndromic cleft lip palate

Asociación entre la variación genética de MSX1 (Hox-7) y la fisura labiopalatina no sindrómica en población chilena / Association between the genetic variation of MSX1 (Hox-7) and non syndromic cleft lip palate in chilean subjects

Background: Homeotic genes have regulatory functions during development. It has been postulated that the human Msx-1 homeotic gene can be involved in the etiology of non syndromic cleft lip palate, since its homologous Msx-1 is involved in cleft palate of mice. Aim: To perform an association analysis between the genetic variation of Msx-1 and non syndromic cleft lip palate in Chilean subjects. Patients and methods: Seventy patients with non syndromic cleft lip palate, 136 healthy relatives of these patients and 69 non related normal individuals were studied. CA microsatellite in Msx- gene, that was amplified with PCR, was studied. Results: No differences in the genetic frequencies of Msx-1 alleles, were observed in the three groups studied. Allelic heterogeneity for allele 2 seems to be related to cases of non syndromic cleft lip palate from multiplex families and heterogeneity for allele 3 is related with simplex families cases. Conclusions: These results seem to support the hypothesis of genetic heterogeneity in the etiology of non syndromic cleft lip palate

Estudio de factores genéticos en la agregación familiar de la esquizofrenia en Santiago, Chile / Genetic factors study in family aggregation of schizophrenia in Santiago, Chile

Forty four randomly selected schizophrenic probands, 22 female, aged 28 to 48 years old, were studied. From them, an extensive genealogic reconstruction was performed. Probands and relatives were interviewed using the structured interview CIDI and DSM-III-R check list. Schizophrenia was diagnosed using DSM-III-R criteria. Complex segregation analysis was done using Pointer program. The hypothesis of a multifactorial inheritance, without the participation of major genes, could not be rejected. Likewise, the major dominant and co-dominant gene forms of transmission could not be rejected. Our results show the participation of a major dominant locus and a multifactorial component in the inheritance of schizophrenia, as has been reported elesewhere

Aspectos genético moleculares del síndrome de X-frágil / Molecular and genetic features of fragile X syndrome

The fragile X syndrome is the most frequent cause of sexlinked mental retardation. In the majority of the cases the mutation responsible for the Martin Bell syndrome is produced when an expansion of the (CGG)n repetition is present in the region 5' of the exón 1 of the gene for X-fragile mental retardation 1 (FMR1), together with a hipermethylation in the CpG promoter region of the gene. The result of this situation is the absence of the FMRP protein coded by the gene. The correlation between length of the (CGG)n sequences and the X-fragile phenotype has permitted a more precise diagnosis of affected and carrier individuals by means of direct DNA analysis. Neverthless the molecular genetic basis of the instability and expansion of the (CGG)n sequences represents a problem not yet resolved. Two morphologic microsatellite (AC)n repetitions, FRAXAC1 and FRAXAC2 that flanck the FMR-1 gene have been recently described. It has been suggested that some haplotypes of FRAXAC1 and FRAXAC2 could be associated to long (CGG)n repetitions and thet these haplotypes would confer more instability to the repeated fragment thus increasing the probability of expansion. It has also been described that the (CGG)n repetition of the FMR-1 gene is interrupted by AGG trinucleotides and that the loss of one AGG would be an important mutational event in the generation of predisposing unstable alleles of the X-fragile syndrome

Tiempos de la erupción dentaria temporal en pacientes con síndrome de Down / Time of temporal dental eruption in patients with Down's syndrome

Se examinaron 255 pacientes con síndrome de Down que asisten a escuelas especiales de Santiago, Chile, con el propósito de describir los tiempos de erupción para la dentición decidual y compararlos con los de la población normal. En los niños con síndrome de Down se observa retraso significativo en la erupción de los siguientes dientes: el incisivo central derecho (15,27 ñ 5,515 meses) y los incisivos laterales derecho e izquierdo (18,44 ñ 9,652 y 18,15 ñ 11,82 meses) y los caninos derecho e izquierdo (25,87 ñ 7,667 y 26,65 ñ 7,431 meses, respectivamente) en el maxilar inferior. Las niñas con síndrome de Down presentan retraso significativo en la erupción de los incisivos laterales derecho e izquierdo (17,31 ñ 14,42 y 17,31 ñ 14,42 meses, respectivamente), los caninos derecho e izquierdo (30,70 ñ 6,454 y 30,60 ñ 7,249 meses, respectivamente, y el primer molar izquierdo 25,87 ñ 14,34 meses) en el maxilar superior; el incisivo central izquierdo (12,02 ñ 7,286 meses), los incisivos laterales derecho e izquierdo (27,59 ñ 10,01 y 24,66 ñ 23,86 meses, respectivamente), los caninos derecho e izquierdo (27,83 ñ 11,25 y 28,80 ñ 10,60 meses, respectivamente) y el segundo molar derecho (28,83 ñ 3,454 meses) en el maxilar inferior. La secuencia de erupción en los niños con s. de Down fue similar a la observada en los normales. Las edades de erupción mostraron una distribución gaussiana y las varianzas existentes en el grupo con s. de Down fueron significativamente superiores a las de los normales

Síndrome X frágil: estudio clínico citogenético y molecular en una familia chilena / Fragile X syndrome: cytogenetical clinic and molecular study in a chilean family

El síndrome del cromosoma X-frágil es la causa más frecuente de retardo mental hereditario en el varón y se asocia a un marcador citogenético ubicado en la banda Xq 27.3 (FRAXA) del cromosoma X. Durante muchos años el diagnostico estuvo basado en la identificación citogenética del marcador; sin embargo, este método no ha resultado confiable para el diagnóstico prenatal y la detección de portadores masculinos o femeninos clínicamente normales. El descubrimiento de las bases moleculares de este síndrome ha permitido desarrollar sondas que posibilitan la identificación confiable de los afectados y los portadores por análisis directo del ADN. Se describen los resultados de un estudio clínico, citogenético y molecular en la familia de una probando X frágil. En el afectado un varón de 2 años 4 meses con retraso mental y dismorfias se comprobó un sitio X frágil, pero su madre y una tía no tenían signos clínicos y sitio frágil. El análisis molecular mostró, en el paciente, una banda de 6,5 Kb, que indicaba la presencia de la mutación causal, mientras la madre exhibía dos bandas, una de 5,2 y otra de 6,0 Kb, que la identifican como heterocigota. En contraste, la tía presentó una sola banda de 5,2 Kb característica de los individuos normales

Cronología de la erupción dentaria permanente en pacientes con síndrome de Down / Chronology of the eruption of the permanent dentition in patients with Down's syndrome

Se examinaron 240 pacientes con síndrome de Down, que asisten a escuelas especiales de Santiago de Chile, con el propósito de determinar la cronología de erupción de la dentición de definitiva y compararla con el patrón de erupción de la población chilena normal. Los niños con síndrome de Down presentan en el maxilar superior e inferior un retraso significativo de la erupción de algunos dientes; éstos son los siguientes: en el maxilar superior, el primer molar derecho (85,35 ñ 20,03 meses) e izquierdo (87,41 ñ 22,37 meses), primer y segundo premolar izquierdo (161,60 ñ 60,43 y 172,10 ñ 79,57 meses, respectivamente) y canino izquierdo (163,72 ñ 81,55 meses). En el maxilar inferior, el primer molar derecho (90,98 ñ 24,52 meses), el incisivo central derecho e izquierdo (84,26 ñ 21,38 y 84,59 ñ 17,72 meses, respectivamente), el incisivo lateral derecho e izquierdo (101,89 ñ 23,79 y 117,53 ñ 83,02 meses, respectivamente) y el canino izquierdo (147,57 ñ 41,54 meses). Las niñas con síndrome de Down presentan en el maxilar superior e inferior retraso significativo en la erupción de los siguientes dientes: en el maxilar superior, los segundos molares derecho e izquierdo (172,71 ñ 83,02 y 191,88 ñ 55,90 meses, respectivamente) y el primer molar izquierdo (84,48 ñ 19,65 meses). En el maxilar inferior, segundo molar y primer premolar derechos (163,30 ñ 59,31 y 131,07 ñ 21,94 meses, respectivamente) y ambos incisivos laterales derecho e izquierdo (102,27 ñ 52,86 y 112,87 ñ 73,47 meses, respectivamente). La secuencia de la erupción dentaria superior e inferior en niños con síndrome de Down comparada con la de la población normal presenta una gran asincronía que afecta a veinte dientes (71,4%). En las niñas con síndrome de Down esta secuencia asincrónica afecta sólo a 15 dientes (53,6%). Una de las principales diferencias entre los individuos Down y normales se debe a la mayor varianza observada en la muestra Down