CHACO outreach project: the development of a primary health care-based medical genetic service in an Argentinean province.

Dissemination of knowledge in genetics to be applied in medicine has created a growing need for capacity building in health care workers. The CAPABILITY ARGENTINA outreach project protocol was designed as a model to introduce genetics in areas without genetic services. Our aim was for genetic health care to become part of primary care in an Argentine province lacking genetic services. The program was innovative as professionals from the referral center (Garrahan Hospital S.A.M.I.C.) traveled to remote areas to train professionals through problem-based education. A logical framework was designed for a local needs assessment. Teaching materials (Powerpoint presentations, printed syllabus, and CD) and a web page were developed. A demonstration project was carried out in the Province of Chaco, Argentina. A total of 485 health workers were trained. The number of consultations increased significantly in participating areas comparing before and after the training period. To support this increase, a complementary project was set up from a public hospital sponsored from within Argentina to build a cytogenetic laboratory in the capital of the Province of Chaco. The model was improved for reproduction in other areas in Argentina. CAPABILITY ARGENTINA is a capacity building model for training of primary care professionals in genetics that may be applied to other medical specialties. The outcomes of the programme have a direct impact on clinical practice.

Influencia de las mutaciones en los genes de conexina en el desarrollo de hipoacusia neurosensorial no sindrómica / Impact of mutations in connexin genes on the development of non-syndromic sensorineural hearing loss

La principal causa de hipoacusia no-sindrómica autosómica recesiva (HNSAR) son mutaciones en el locus DFNB1, que contiene los genes GJB2 (conexina 26) y GJB6 (conexina 30). Se han descripto más de 100 mutaciones diferentes en GJB2. Dos deleciones en GJB6, del (GJB6-D13S1830) y del(GJB6-D13S1854) mostraron ser prevalentes en España. El objetivo de este trabajo fue determinar la prevalencia de mutaciones en los genes GJB2 y GJB6, en niños con HNSAR de Argentina. Este estudio incluyó 113 niños no relacionados con hipoacusia neurosensorial no-sindrómica moderada a profunda. Para el análisis molecular se utilizó una estrategia en etapas. La mutación 35delG (gen GJB2) se analizó mediante PCR-RFLP. La presencia de deleciones en GJB6 se investigó por PCR múltiple. Las muestras no resueltas en las dos primeras etapas fueron analizadas por secuenciación directa del gen GJB2. En 58 pacientes se encontraron alteraciones en la secuencia de los genes GJB2/GJB6. La mutación 35delG se detectó en 52 de los 84 alelos con mutaciones patogénicas. Se identificaron 16 variantes de secuencia diferentes; entre ellas una mutación no descripta previamente, 262G>C (A88P). La deleción del (GJB6-D13S1830) fue identificada en 7 alelos. La frecuencia de mutaciones en GJB2/GJB6 encontrada en este trabajo está en concordancia con la de otras poblaciones caucásicas. La mutación más prevalente fue 35delG y la segunda mutación más común la deleción del (GJB6-D13S1830), con frecuencias similares a las encontradas en España, desde donde Argentina recibió una de sus mayores olas inmigratorias. Estos resultados destacan la importancia del estudio de los genes GJB2/GJB6 en el diagnóstico etiológico de sordera permitiendo un tratamiento precoz y un asesoramiento genético oportuno.

The main cause of autosomal recessive nonsyndromic hear-ing loss (ARNSHL) are mutations in genes GJB2 (connexin 26) and GJB6 (connexin 30) at the DFNB1 locus. More than 100 different mutations in GJB2 have been described. Two dele-tions in GJB6, of (GJB6-D13S1830) and of (GJB6-D13S1854) have been found prevalent in Spain. The aim of this study was to determine the prevalence of GJB2 and GJB6 gene muta-tions in children with ARNSHL in Argentina. In the study, 113 non-related children with moderate to profound nonsyndromic sensorineural hearing loss were included. A staging strategy was used for molecular analysis. The 35delG mutation (gene GJB2) was analyzed using PCR-RFLP. The presence of de-letions in GJB6 was tested by multiplex PCR. Samples that were not resolved in the first two stages were subsequently assessed by direct sequencing of the GJB2 gene. In 58 patients abnormal patterns were found in the GJB2/GJB6 sequences. The 35delG mutation was detected in 52 of the 84 alleles with pathogenic mutations. Sixteen different sequence variants were identified of which one, 262G>C (A88P), was not previously described. Deletion of (GJB6-D13S1830) was identified in 7 alleles. The rate of mutations in GJB2/GJB6 found in this study is similar to that reported in other Caucasian populations. The most prevalent mutation was 35delG followed by a deletion of (GJB6-D13S1830), with a rate similar to that found in Spain from which Argentina received one of the largest waves of immigrants. These results emphasize the need to study GJB2/GJB6 genes in the etiological diagnosis of hearing loss allowing for early treatment and adequate genetic counseling.

Duplication dup(1)(q41q44) defined by fluorescence in situ hybridization: delineation of the 'trisomy 1q42-->qter syndrome'.

We report on a novel case of pure partial tandem duplication 1q42q43 confirmed by fluorescence in situ hybridization (FISH). We compare the manifestations of our patient with similar cases previously reported. We conclude that the most common clinical manifestations of trisomy 1q42qter are prenatal and postnatal growth retardation, relative macrocephaly, triangular face, prominent forehead, broad nasal bridge, abnormal philtrum, micro/retrognathia, cardiac defects and mental retardation. We would like to emphasize the importance of the FISH technique in the identification of the duplicated segment.

A combination of five short tandem repeats of chromosome 15 significantly improves the identification of Prader-Willi syndrome etiology in the Argentinean population.

Prader-Willi syndrome (PWS) is a multisystemic disorder caused by the loss of expression of paternally transcribed genes in the PWS critical region of chromosome 15. Various molecular mechanisms are known to lead to PWS: deletion 15q11-q13 (75% of cases), maternal uniparental disomy (matUPD15) (23%) and imprinting defects (2%). FISH and microsatellite analysis are required to establish the molecular etiology, which is essential for appropriate genetic counseling and care management. We characterized an Argentinean population, using five microsatellite markers (D15S1035, D15S11, D15S113, GABRB3, D15S211) chosen to develop an appropriate cost-effective method to establish the parental origin of chromosome 15 in nondeleted PWS patients. The range of heterozygosity for these five microsatellites was 0.59 to 0.94. The average heterozygosity obtained for joint loci was 0.81. The parental origin of chromosome 15 was established by microsatellite analysis in 19 of 21 non-deleted PWS children. We also examined the origin of the matUPD15; as expected, most of disomies were due to a maternal meiosis I error. The molecular characterization of this set of five microsatellites with high heterozygosity and polymorphism information content improves the diagnostic algorithm of Argentinean PWS children, contributing significantly to adequate genetic counseling of such families.

A combination of five short tandem repeats of chromosome 15 significantly improves the identification of Prader-Willi syndrome etiology in the Argentinean population

Prader-Willi syndrome (PWS) is a multisystemic disorder caused by the loss of expression of paternally transcribed genes in the PWS critical region of chromosome 15. Various molecular mechanisms are known to lead to PWS: deletion 15q11-q13 (75% of cases), maternal uniparental disomy (matUPD15) (23%) and imprinting defects (2%). FISH and microsatellite analysis are required to establish the molecular etiology, which is essential for appropriate genetic counseling and care management. We characterized an Argentinean population, using five microsatellite markers (D15S1035, D15S11, D15S113, GABRB3, D15S211) chosen to develop an appropriate cost-effective method to establish the parental origin of chromosome 15 in nondeleted PWS patients. The range of heterozygosity for these five microsatellites was 0.59 to 0.94. The average heterozygosity obtained for joint loci was 0.81. The parental origin of chromosome 15 was established by microsatellite analysis in 19 of 21 non-deleted PWS children. We also examined the origin of the matUPD15; as expected, most of disomies were due to a maternal meiosis I error. The molecular characterization of this set of five microsatellites with high heterozygosity and polymorphism information content improves the diagnostic algorithm of Argentinean PWS children, contributing significantly to adequate genetic counseling of such families.

Aneuploidias cromosómicas sexuales detectadas mediante FISH en células de la mucosa bucal de pacientes con diagnóstico presuntivo de sindrome de turner / Detection of sex chromosome aneuploidy by FISH in cells of the oral mucosa in patients with presumptive diagnosis of turner syndrome

La técnica de hidratación in situ con fluorescencia (FISH) detecta aneuploidias cromosómicas en células interfásicas. En el presente trabajo se efectuó esta técnica, en células de la mucosa bucal, con el objetivo de detectar bajos niveles de mosaicismo en pacientes con diagnóstico presuntivo de Sindrome de Turner (ST) y cariotipo normal en sangre periférica. Un segundo objetivo fue el de comparar la frecuencia de mosaicismos en ambos tejidos. En el período 1988-2000 se seleccionaron 110 pacientes que ingresaron al laboratorio de citogenética con diagnóstico presuntivo de ST y cariotipo normal o mosaico. De estas solo 18 pudieron ingresar en el presente estudio (8 con cariotipo 46,XX, 7 con mosaicos involucrando al cromosoma X y 3 con mosaicos con material del cromosoma Y). Se estudió con grupo control constituido por 10 mujeres normales. Fueron analizados 200 o más núcleos interfásicos de la mucosa bucal por individuo. La sensibilidad analítica de la sonda fue del 96%. Se halló mosaicismo en 2 pacientes 46,XX (11,5% y 14,55%) el cual fue corroborado en un segundo estudio. En las pacientes mosaicos se observaron las mismas líneas celulares por ambas metodologías pero discordancia en su frecuencia. Este trabajo sugiere que FISH en células de la mucosa bucal podría ser una metodología alternativa para detectar mosaicismos tejido especificos. Es un buen complemento de la citogenética clásica al permitir acceder a un mayor conocimiento de la constitución cromosómica en pacientes con rasgos relevantes de ST y cariotipo normal.

Diagnostico de desnutricion y de riesgo de desnutricion en un hospital general de adultos / Diagnosis of malnutrition and risk of malnutrition in general hospital of adults

Antecedentes: hasta el momento, se desconoce la prevalencia de la desnutrición y del riesgo de la desnutrición en los pacientes internados en los hospitales generales de adultos del pais. Sólo existen informes parciales sobre desnutrición en afecciones médicas y en pacientes neoplásicos con y sin metástasis. Objetivos Conocer la prevalencia de la desnutrición y de riesgo de la desnutrición en pacientes internados en un hospital genera] de adultos (Hospital Pasteur, Montevideo, Uruguay) excluidas las áreas de medicina intensiva. 2. Determinar la constancia del diagnóstico nutricional en las historias clínicas de los pacientes. Material y métodos Encuesta sobre el estado nutricional de 179 pacientes internados en áreas médico-quirúrgicas no críticas del hospital, utilizando una Escala de Categorización Mutricional basada en la valoración global subjetiva (VGS) (A = bien nutridos; B = En riesgo de desnutrición; C= Desnutrición moderada; D = Desnutrición severa), cotejando su rendimiento con el índice de masa corporal (IMC) y la auditoría de las historias clínicas de los mismos pacientes, para determinar la constancia del diagnóstico nutricional y de peso-talla en las mismas. Resultados De los 179 pacientes encuestados, y de acuerdo a la escala propuesta, 39 (25 en C; 14 en D) estaban desnutridos (21.5 por ciento) y 37 (21 por ciento) estaban en riesgo de desnutrición (B). El IMC correspondiente a C y D es, de modo muy significativo, menor que el de A (p < 0.001). Sin embargo, A no es significativamente diferente de B, ni C lo es deD. En las 179 historias clínicas auditadas, sólo 24 (13.4 por ciento) tenían constancia del diagnóstico nutricional y ninguna presentó, en forma conjunta, los datos de peso y talla. Conclusiones Existe una alta prevalencia de desnutrición moderada-severa y de riesgo de desnutrición en la población hospitalaria encuestada, según la escala utilizada. Ésta se demostró más adecuada que el IMC per se para la categorización nutricional. Éste último no discrimina entre A y B ni entre C y D. Además, el IMC se altera en presencia de edemas y/o ascitis...

Complete screening of the CFTR gene in Argentine cystic fibrosis patients.

In order to establish the nature and the distribution of mutations causing cystic fibrosis (CF) in 220 unrelated Argentine families, the present authors conducted an extensive molecular analysis of the CF transmembrane regulator (CFTR) gene. First, a direct mutation analysis of 13 common mutations was done, enabling the detection of 319 out of 440 CF alleles (72.52%). Then an exhaustive screening of the entire coding region and the adjacent sequences of the CFTR gene was performed in all patients carrying at least one unidentified CF allele using the multiplex heteroduplex analysis assay followed by direct DNA sequencing. Thirty-nine different CF mutations, including five previously undescribed mutations (i.e. L6V, Y362X, 1353insT, 2594delGT and 2686insT) and two novel polymorphisms (i.e. 1170G/C and 3315A/C) were identified. As a result, the overall detection rate increased by up to 83.45%. Besides DeltaF508, only five mutations showed frequencies higher than 1%. In addition, a total of 49% of the mutations were rare because they were found in only one CF family. This wide spectrum of CF mutations is in agreement with the heterogeneous ethnic origin of the Argentine population. The data obtained here may have important consequences for the development of adequate strategies for the molecular diagnosis of CF in Argentina.

[Characterization of 3 microsatellites of the cystic fibrosis gene in Argentine families]. / Caracterización de tres microsatélites del gen de fibrosis quística en familias argentinas.

Argentine population is highly heterogeneous for the cystic fibrosis (CF) transmembrane regulator (CFTR) gene mutations. The study of 14 more common mutations identified both mutated alleles in only 51% of patients. This study confirmed the diagnosis of cystic fibrosis in these patients and enabled the detection of asymptomatic carriers in their families. However, in the remaining patients the direct molecular assay did not provide the necessary information for genetic counselling. To establish the mutated allele transmission in the affected families, negative for the most common mutations, three microsatellites (IVS17bTA, IVS8CA and IVS17bCA) located in intronic regions of CFTR gene were studied. In the 40 CF families analyzed, different allelic variants were detected: 15 for IVS17bTA, 10 for IVS8CA and 4 for IVS17bCA. Polymorphism information content and heterozygosity were high, except for IVS17bCA. By the simultaneous analysis of the three microsatellites we could counsel 100% of the families. Ours results show that these microsatellites are an excellent group of markers for linkage studies in cystic fibrosis families of the Argentine population.

Spondylo-meta-epiphyseal dysplasia, short limbs, abnormal calcification type: a new case with severe neurological involvement.

A case of an affected girl with spondylo-meta-epiphyseal dysplasia (SMED) is reported. The disease was detected at birth as a congenital dysplasia with generalized lesions. At 10 months of age, abnormal calcifications appeared in both wrists. The patient evolved with severe growth retardation and multiple neurological and respiratory complications, followed by death at 21 months of age.

Caracterización de tres microsatélites del gen de fibrosis quística en familias argentinas. / [Characterization of 3 microsatellites of the cystic fibrosis gene in Argentine families]

Argentine population is highly heterogeneous for the cystic fibrosis (CF) transmembrane regulator (CFTR) gene mutations. The study of 14 more common mutations identified both mutated alleles in only 51

of patients. This study confirmed the diagnosis of cystic fibrosis in these patients and enabled the detection of asymptomatic carriers in their families. However, in the remaining patients the direct molecular assay did not provide the necessary information for genetic counselling. To establish the mutated allele transmission in the affected families, negative for the most common mutations, three microsatellites (IVS17bTA, IVS8CA and IVS17bCA) located in intronic regions of CFTR gene were studied. In the 40 CF families analyzed, different allelic variants were detected: 15 for IVS17bTA, 10 for IVS8CA and 4 for IVS17bCA. Polymorphism information content and heterozygosity were high, except for IVS17bCA. By the simultaneous analysis of the three microsatellites we could counsel 100

of the families. Ours results show that these microsatellites are an excellent group of markers for linkage studies in cystic fibrosis families of the Argentine population.

Fragile X founder effects in Argentina.

To investigate the origin of fragile X mutations in the Argentine population, we studied the alleles and haplotypes at DXS548 and FRAXAC1 loci of 42 unrelated fragile X chromosomes and 168 normal ones. Four haplotypes presented in linkage disequilibrium and accounted for 76.2% of fragile X chromosomes, representing the high frequency of haplotype DXS548-FRAXAC1 7-1 (26.2%) characteristic of our population. FRAXAC1 allele 1 was observed on 47.6% of fragile X chromosomes. Thus, we provide evidence for fragile X founder effects in the Argentine population, similar to those observed in Caucasians and in Asians.

Deletion patterns in Argentine patients with Duchenne and Becker muscular dystrophy.

The identification of mutations in Duchenne or Becker muscular dystrophy (DMD/BMD) patients is important for carrier detection in these families. We present the patterns of deletions of the dystrophin gene in Argentine population. DNA from 75 patients with DMD/BMD was analyzed by multiplex PCR and, in some cases, cDNA/Southern. Deletions were detected in 24 patients (32%) and were mainly clustered in two areas of the dystrophin gene: the 5' end (exons 3-12) and the central part (exons 44-53). 64% of the deletion endpoints lay in the middle region and 34% in the 5' end of the gene. The most frequent sites for deletion-endpoints were in the introns 47 (13.6%), 44 (11%), 2 (9%) and 12 (7%). Thus, the proportion and distribution of deletions in our DMD/BMD patients differ from those reported for other populations. Furthermore, a higher proportion of deletions was observed in familial cases (40%) than in isolated ones (30%), in contrast to previously reported data. The effect of the deletion on the reading frame agree with the phenotype in almost all the patients studied. This study will be useful in prenatal diagnosis and diagnosis of other Argentine DMD patients.

Clinical, cytogenetic, and molecular testing of Argentine patients with retinoblastoma.

PURPOSE: The purpose of this study is to determine the clinical, chromosomal, and molecular characteristics of Argentine patients with unilateral and bilateral retinoblastoma. STUDY DESIGN: Eighty-six patients belonging to 82 families were studied; 59% of them were examined during the first year of life. Leukocoria was the most common reason for consultation. Other presenting signs were strabismus and glaucoma. Enucleation of the affected eye was performed in 85% of the cases and the complication rate was 13%. RESULTS: An appropriate therapy allowed the survival of 84 of the 86 patients. Two children with malformations and growth retardation had an abnormal karyotype with a deletion in 13q14. Segregation analysis of polymorphic sites within the retinoblastoma gene and the parental origin of the allele lost in the tumor were analyzed in 30 of the 82 families. Five mutant alleles transmitted through the germline and six de novo germline mutant alleles were identified in 12 patients with hereditary retinoblastoma. Most de novo germline mutant alleles were paternally derived. Molecular analysis of nonhereditary retinoblastoma showed loss of heterozygosity in three of eight cases. From these, two maternal alleles and one paternal allele were lost, thus not indicating a significant difference in the parental origin for the lost allele. CONCLUSIONS: These data are useful for deoxyribonucleic acid diagnosis of susceptibility to retinoblastoma in relatives of hereditary patients, even if mutations have not been identified.

Carrier detection in Duchenne and Becker muscular dystrophy Argentine families.

In order to offer carrier detection, genetic counseling, and prenatal diagnosis to families with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) in our country, segregation analysis of highly polymorphic short tandem repeats (STR) (dC-dA)n: (dG-dT)n loci was utilized. The risks to females of 15 DMD BMD families (9 familial and 6 sporadic) were evaluated on STR, pedigree and serum creatine kinase (SCK) data. From the 36 females at risk of being carriers (not including 8 obligate carriers), results of STR analysis were compatible with carrier status in 7 and not compatible in 20. In 9 females, no information regarding carriership was derived from the STR analysis. Prenatal diagnosis is now possible on the carrier females. Previously identified deletions in the central part of the gene were confirmed by STR analysis in 3 families. Five new alleles were identified in Argentine individuals; allele frequencies differed from those of North American people. Results derived from this study are useful for carrier detection and genetic counseling in DMD/BMD. One case of probable mosaicism in an unaffected father was detected on a pedigree basis in a family with DMD patients.

Spectrum of CFTR mutations in Argentine cystic fibrosis patients.

The identification of different mutations which cause cystic fibrosis (CF) in Argentine patients has been performed. Initially, 10 of the most commonly mutated loci in 228 independent chromosomes were analyzed. Each allele was detected by PCR amplification of DNA samples either directly on polyacrylamide gels, by restriction enzyme digestion and agarose gels electrophoresis, or by hybridization with allele specific oligonucleotides. The delta F508 mutation was found in 57% of the alleles. The frequencies of the other CF mutations were as follows: G542X 3.9%, W1282X 3.1%, N1303K 1.7%, 1717 1-G-->A 0.9%, R553X 0.4%, R1162X 0.4%, whereas G551D, delta I507 and S549N were not found. This direct mutation analysis enabled the detection of 155/228 CF alleles (67%). Of the remaining 73 unidentified CF alleles, 22 were investigated for the 27 exons by DGGE and 9 rare mutations were identified. The incidence of the main CF mutations analyzed was similar to that of the South European population and markedly different from other Latin American countries. The mutation data presented here may be useful for designing DNA testing strategies for CF in Argentina.

Tandem triplication and quadruplication of chromosome 21 in childhood acute lymphoblastic leukemia.

A 5-year-old girl with ALL was shown to have a leukemic clone characterized by a triplication and quadruplication of chromosome 21, arranged in tandem, at diagnosis and relapse, respectively. To our knowledge, this is the second report of this chromosomal anomaly in ALL, which was confirmed by in situ staining. The karyotype evolution in the leukemic clone from triplication to quadruplication at relapse emphasizes the association of chromosome 21 with hematopoietic malignancies.