Change in prevalence of congenital defects in children with Prader-Willi syndrome.

OBJECTIVE: The aim of this study was to assess the prevalence of congenital defects observed in patients with Prader-Willi syndrome (PWS) and to compare this prevalence with that described in the general population. In addition, these findings were correlated with the different etiologic subtypes. METHODS: A total of 180 children with PWS followed for 13 years were included in this study. Diagnosis was confirmed by the methylation test, and genetic subtypes were established by using fluorescence in situ hybridization or multiplex ligation-dependent probe amplification and microsatellite analyses. The prevalence of congenital defects was compared with national and international registries of congenital defects in the general population (Estudio Colaborativo Latinoamericano de Malformaciones Congénitas, European Surveillance of Congenital Anomalies, and the New York Registry). RESULTS: Twenty-two percent of the patients presented congenital defects with a risk of 5.4 to 18.7 times higher than that of the general population. The most frequent congenital defects were heart defects, renoureteral malformations, vertebral anomalies, hip dysplasia, clubfoot, and agenesis/hypoplasia of the corpus callosum. Each of these congenital defects was significantly more frequent in the children with PWS than in the general population. The congenital heart defects were more frequent in girls than in boys with PWS. No significant differences were found when the defects were correlated with the different etiologic subtypes. CONCLUSIONS: An increased prevalence of congenital defects was found in our PWS patients. This finding suggests the need for further studies in PWS children that allow physicians to detect the congenital defects found in this series and, thus, to anticipate complications, with the ultimate aim of enhancing the management of PWS patients.

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.

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.

[Angelman syndrome: the electroclinical characteristics in 35 patients]. / Sindrome de Angelman: características electroclínicas en 35 pacientes.

AIMS: The purpose of this study is to report on 35 patients with Angelman syndrome (AS) in whom we evaluated the electroclinical characteristics and the progression of their epilepsy. PATIENTS AND METHODS: The following factors were evaluated: sex, family background, neurological examination, age at onset and semiology of the epileptic seizures, EEG, types of epilepsy according to the international classification and response to therapy. We investigated the karyotype, and conducted FISH and methylation tests for AS. RESULTS: The 35 patients had an average follow up time of 5.6 years. Epilepsy was diagnosed in 25 cases, with an average age of onset of 1.6 years. The epileptic syndromes were: epilepsy with myoclonic seizures in 13, of which seven presented a myoclonic state in their history, focal epilepsy in seven, West's syndrome in three, and Lennox Gastaut syndrome in two. Intercritical EEG showed generalised MSW and SW paroxysms in 13, unilateral spikes in seven, hypsarrhythmia in three, generalised fast rhythm paroxysms and slow SW activity in two. Basal electroencephalographic activity was: slow hypervoltage waves with or without inserted spikes situated at the rear in 19, at the front in six, diffuse in six, and normal in four cases. CONCLUSIONS: 71.4% of patients with AS suffered epileptic seizures; epilepsy with myoclonic seizures was the most frequently observed epileptic syndrome and hypervoltage slow wave activity with or without spikes inserted in the posterior quadrants was a characteristic encephalographic pattern. In patients with mental retardation, with or without epilepsy and these electroencephalographic findings, even in the absence of characteristic clinical signs, methylation and FISH analyses for AS should be performed.

Síndrome de Angelman: características electroclínicas en 35 pacientes / Angelman syndrome: the electroclinical characteristics in 35 patients

Objetivo. Presentar 35 pacientes con síndrome de Angelman (SA) en los que se evaluaron las características electroclínicas y el curso evolutivo de la epilepsia. Pacientes y métodos. Evaluamos: sexo, historia familiar, examen neurológico, edad de inicio y semiología de las crisis epilépticas, EEG, tipos de epilepsia de acuerdo a la clasificación internacional y respuesta al tratamiento. Investigamos cariotipo, FISH y test de metilación para SA. Resultados. Los 35 pacientes tuvieron un tiempo promedio de seguimiento de 5,6 años. La epilepsia se diagnosticó en 25 casos, con una mediana para la edad de inicio de 1,6 años. Los síndromes epilépticos fueron: epilepsia con crisis mioclónicas en 13, de los cuales siete presentaron estado miocló nico en su evolución, epilepsia focal en siete, síndrome de West en tres, síndrome de Lennox-Gastaut en dos. El EEG intercrítico mostró paroxismos generalizados de PPO y PO en 13, espigas unilaterales en siete, hipsarritmia en tres, paroxismos generalizados de ritmos rápidos y actividad de PO lenta en dos. La actividad electroencefalográfica basal fue: ondas lentas hipervoltadas con o sin espigas intercaladas de localización posterior en 19, anterior en seis, difusas en seis; y normal, cuatro casos. Conclusiones. El 71,4 por ciento de los pacientes con SA tuvieron crisis epilépticas; la epilepsia con crisis mioclónicas fue el síndrome epiléptico más frecuente y la actividad de OL hipervoltadas con o sin espigas intercaladas en cuadrantes posteriores fue patrón electroencefalográfico característico. En pacientes con retraso mental, con o sin epilepsia y estos hallazgos electroencefalográficos, aun en ausencia de signos clínicos característicos, deberíamos realizar test de metilación y FISH para SA (AU)

Aims. The purpose of this study is to report on 35 patients with Angelman syndrome (AS) in whom we evaluated the electroclinical characteristics and the progression of their epilepsy. Patients and methods. The following factors were evaluated: sex, family background, neurological examination, age at onset and semiology of the epileptic seizures, EEG, types of epilepsy according to the international classification and response to therapy. We investigated the karyotype, and conducted FISH and methylation tests for AS. Results. The 35 patients had an average follow-up time of 5.6 years. Epilepsy was diagnosed in 25 cases, with an average age of onset of 1.6 years. The epileptic syndromes were: epilepsy with myoclonic seizures in 13, of which seven presented a myoclonic state in their history, focal epilepsy in seven, West's syndrome in three, and Lennox-Gastaut syndrome in two. Intercritical EEG showed generalised MSW and SW paroxysms in 13, unilateral spikes in seven, hypsarrhythmia in three, generalised fast-rhythm paroxysms and slow SW activity in two. Basal electroencephalographic activity was: slow hypervoltage waves with or without inserted spikes situated at the rear in 19, at the front in six, diffuse in six, and normal in four cases. Conclusions. 71.4% of patients with AS suffered epileptic seizures; epilepsy with myoclonic seizures was the most frequently observed epileptic syndrome and hypervoltage slow wave activity with or without spikes inserted in the posterior quadrants was a characteristic encephalographic pattern. In patients with mental retardation, with or without epilepsy and these electroencephalographic findings, even in the absence of characteristic clinical signs, methylation and FISH analyses for AS should be performed (AU)

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.

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.

[Nontuberculous mycobacteria in patients with cystic fibrosis]. / Microbacterias no tuberculosas en pacientes con fibrosis quistica.

The prevalence of nontuberculous mycobacteria (NTM) isolated from the lower airways of adult cystic fibrosis (CF) patients appears to be increasing. Different centers of USA, England, Sweden and Ireland have reported a prevalence ranging from 1.5 to 19.5%. The aim of the present study was to investigate the presence of NTM in patients assisted at these centers. A total of 92 sputum specimens and/or gastric contents from 40 CF patients were studied. Ages of patients ranged from 4 months to 25 years. Samples were obtained during acute exacerbation or in routine check-up. Mycobacterium avium-intracellulare complex strains were isolated from six patients with moderate or severe clinical manifestations. Five of these patients were considered as being colonized by NTM. Active mycobacterial disease was diagnosed in one patient and he underwent treatment. The index of bacterial contamination of cultures was very high early along the study (57%), decreasing to 2.8% later due to a change in the methodology used in the processing of samples. It was concluded that the presence of NTM is relatively frequent in patients with CF, even in children with moderate or severe compromise, a fact which strongly suggests that NTM should be systematically searched for considering the possibility that the patients might develop active disease.

Diagnóstico de fibrosis quística del páncreas en recién nacidos con ileo meconial / Diagnosis of cystic fibrosis in newborns with meconium ileus

En un grupo de 17 neonatos con ileo meconial tratados en los últimos 6 años en nuestro Hospital, se evaluó a aquellos que presentaban fibrosis quística del páncreas (FQP) y se los comparó con los que no la padecían. Doce pacientes pudieron ser estudiados en forma completa. El 50 por ciento (n:6) de estos pacientes presentó FQP. Al comparar este grupo con aquellos sin FQP, encontramos que la recuperación del peso de nacimiento llevó el doble de tiempo: el 100 por ciento se encuentran desnutridos (perc < 3) y con enfermedad respiratoria crónica. La sobrevida fue del 100 por ciento para los que no preseentaron FQP y del 83,4 por ciento para los que la padecieron. Concluímos que ante el diagnóstico de ileo meconial. El equipo tratante deberá agotar las instancias diagnósticas para pesquizar FQP. La metodología debe incluir estudio genético del niño y sus padres. Un correcto y precoz diagnóstico de FQP permite un manejo nutricional y respiratorio que ayude a prevenir las múltiples complicaciones que padecen estos niños

Diagnóstico de fibrosis quística del páncreas en recién nacidos con ileo meconial / Diagnosis of cystic fibrosis in newborns with meconium ileus

En un grupo de 17 neonatos con ileo meconial tratados en los últimos 6 años en nuestro Hospital, se evaluó a aquellos que presentaban fibrosis quística del páncreas (FQP) y se los comparó con los que no la padecían. Doce pacientes pudieron ser estudiados en forma completa. El 50 por ciento (n:6) de estos pacientes presentó FQP. Al comparar este grupo con aquellos sin FQP, encontramos que la recuperación del peso de nacimiento llevó el doble de tiempo: el 100 por ciento se encuentran desnutridos (perc < 3) y con enfermedad respiratoria crónica. La sobrevida fue del 100 por ciento para los que no preseentaron FQP y del 83,4 por ciento para los que la padecieron. Concluímos que ante el diagnóstico de ileo meconial. El equipo tratante deberá agotar las instancias diagnósticas para pesquizar FQP. La metodología debe incluir estudio genético del niño y sus padres. Un correcto y precoz diagnóstico de FQP permite un manejo nutricional y respiratorio que ayude a prevenir las múltiples complicaciones que padecen estos niños

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.

Molecular characterization of HLA class II genes in celiac disease patients of Latin American Caucasian origin.

In the present study, the polymorphic domain of HLA class II genes present in a pediatric population of Argentinian celiac disease patients was analyzed by hybridization to sequence-specific oligonucleotides and DNA sequencing. Sixteen out of 16 DR5/7 heterozygous patients bore the DQA1*0501 and DQB1*0201 alleles implicated in the DQ2 risk specificity. The second exon of DQA1, DQB1 and DRB1 genes from 2 DR5/7 patients was characterized by DNA sequencing. The following alleles were found in both patients: DRB1*1101 and DRB1*0701; DQB1*0301 and DQB1*0201; DQA1*0501 and DQA1*0201. Previous serological analysis in this population had shown the presence of DQ2 in 95% of the patients (40% in controls) and a negative association with DQ1 haplotypes, suggesting the presence of other "permissive" or neutral alleles. The following HLA-DQB1 alleles, besides DQB1*0201, were identified in 31 CD patients: DQB1*0301, 0302, 0401 and 0402. All these alleles share a common pattern of residues between positions 84 and 90, and distinct from that present in DQ1-related alleles.

Complete nucleotide sequence of a genomic clone encoding HLA-B35 isolated from a Caucasian individual of Hispanic origin. Identification of a new variant of HLA-B35.

The primary structure of an HLA class I genomic clone isolated from a homozygous HLA-B35 Caucasian individual of hispanic origin was determined. The nucleotide sequence of exons 1, 2, 4, 5, 6, and 7 is identical to that of the HLA-B35 allele of Oriental origin reported previously. Exon 3 differs in only three nucleotides present in a stretch of 23 bp. These changes introduce three amino acid substitutions in residues 109 (Leu----Phe), 114 (Asp----Asn), and 116 (Ser----Tyr), two of which (114 and 116) are located in one of the beta sheets at the bottom of the peptide binding site. The nature of these replacements in this HLA-B35 variant is likely to affect peptide binding and recognition by T lymphocytes. Introns 1, 2, 3, 4, 5, and 6 from this genomic clone are identical to those present in HLA-Bw58, further confirming the evolutionary origin of HLA-B35.

HLA and celiac disease in Argentina: involvement of the DQ subregion.

A population of 62 unrelated homogeneous Argentinian celiac pediatric patients were typed for HLA-A,B,C,DR, and DQ antigens. The association between celiac disease and the DR3 and DR7 antigens was confirmed. The specificity DQw2 was present in 95.2 per cent of the patients. Nevertheless, it was of interest that the most significant phenotypes observed were DR3/DR7, DR7/DR5, and DR3/DR5. The significance of these findings is discussed.

Restriction fragment length polymorphism in HLA class II genes of Latin-American Caucasian celiac disease patients.

In the present study Latin-American celiac disease patients were analyzed for the frequency of certain HLA class II restriction fragment length polymorphisms in order to investigate whether they exhibited the normal associated alleles or showed unusual class II variants. A DPB/RsaI 4.0-kb fragment that was shown to be significantly increased among North Americans celiac disease patients of the DR3,DQw2 haplotype was found with similar frequency in Latin-American control and celiac disease individuals. A DPA/BglII 3.7-kb fragment previously shown to be increased among British celiac disease patients was also present with similar frequency among Latin-American control and celiac disease individuals. These results show that the frequency of the HLA-DP region-derived restriction fragment length polymorphisms linked to celiac disease differs between Caucasian populations of different ethnic backgrounds (Anglo-Saxon and Latin-American). On the other hand, DNA samples from 13 patients and 14 controls bearing the DR5/DR7 phenotype (which is significantly associated with celiac disease in Latin populations) were investigated for the presence of particular restriction fragment length polymorphisms disproportionally present in celiac disease individuals. No significant differences were found between controls and patients when the DNA was analyzed with 10 different restriction enzymes and probes for DRB, DQA, DQB, and DPB HLA class II sequences.