Survival-Related Genes on Chromosomes 6 and 17 in Medulloblastoma.

Survival of Medulloblastoma (MB) depends on various factors, including the gene expression profiles of MB tumor tissues. In this study, we identified 967 MB survival-related genes (SRGs) using a gene expression dataset and the Cox proportional hazards regression model. Notably, the SRGs were over-represented on chromosomes 6 and 17, known for the abnormalities monosomy 6 and isochromosome 17 in MB. The most significant SRG was HMGA1 (high mobility group AT-hook 1) on chromosome 6, which is a known oncogene and a histone H1 competitor. High expression of HMGA1 was associated with worse survival, primarily in the Group 3γ subtype. The high expression of HMGA1 was unrelated to any known somatic copy number alteration. Most SRGs on chromosome 17p were associated with low expression in Group 4ß, the MB subtype, with 93% deletion of 17p and 98% copy gain of 17q. GO enrichment analysis showed that both chromosomes 6 and 17 included SRGs related to telomere maintenance and provided a rationale for testing telomerase inhibitors in Group 3 MBs. We conclude that HMGA1, along with other SRGs on chromosomes 6 and 17, warrant further investigation as potential therapeutic targets in selected subgroups or subtypes of MB.

Haplotype-based Analysis of 6q24-25 for Association with Rheumatoid Arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a multisystem inflammatory disorder. Family history of RA is an important risk factor as it is strongly linked with the inherited HLA-DR4 (most specifically DR0401 and 0404). The aim of this study is to conduct the haplotype-based analysis of 6q24-25 and evaluate its association with RA. MATERIALS AND METHODS: Case-control study which included all patients attending outpatient department (OPD) at Sardar Patel Medical College, Bikaner, Rajasthan and volunteers (only for blood samples). Blood samples of patients were collected. As per inclusion and exclusion criteria, a total of 103 subjects lacking history of disease were included under control group, while 48 cases were recruited as study group. Any significant departure of genotype distribution is evaluated using Hardy-Weinberg equilibrium by Chi-squared test. RESULTS: Case-control association was done using data from 151 genomic deoxyribonucleic acid (DNA) samples, which were allele typed. RA is significantly associated with >305bp (the longer allele of D6S1053 corresponding to 11 tetramer (GATA) repeats. Differences in individual allele frequency within the control population and RA cases were observed which shows the bimodal distribution of the 10 alleles of D6S1053 short tandem repeat (STR) marker observed in the cohort tested by us. No significant association with the risk for RA is shown by the allele for D6S1053 and the mutant allele 118G. Similarly, OPRM1 gene's haplotype frequency for rs1799972 for D6S1053 allele has not shown any added risk with the wild allele 17C compared to controls. The polymorphism showed that 17T depicted a higher odds ratio of 1.3 with an associated risk of 1.15 in the presence of longer allele of DS61053. Significance observed between short allele and RA was lost when haplotype analysis for the two genes were taken together. There was no difference observed between the short or long allele and 17T/C while there was a significant difference observed when haplotype frequencies were compared with alleles of A118G and the long and short allele of DS61053. CONCLUSION: We concluded that the short allele of µ-opioid receptor (MOR) gene offered a clear protection from a risk of getting RA.

[Application of optical genome mapping technology for the detection of chromosomal structural variations].

OBJECTIVE: To assess the value of optical genome mapping (OGM) for the detection of chromosomal structural abnormalities including ring chromosomes, balanced translocations, and insertional translocations. METHODS: Clinical data of four patients who underwent pre-implantation genetic testing concurrently with OGM and chromosomal microarray analysis at the Center of Reproductive Medicine of the Sixth Affiliated Hospital of Sun Yat-sen University from January to October 2022 due to chromosomal structural abnormalities were selected as the study subjects. Some of the results were verified by multi-color fluorescence in situ hybridization. RESULTS: The OGM has successfully detected a balanced translocation and fine mapped the breakpoints in a patient. Among two patients with insertional translocations, OGM has provided more refined breakpoint locations than karyotyping analysis in a patient who had chromosome 3 inserted into chromosome 6 and determined the direction of the inserted fragment. However, OGM has failed to detect the chromosomal abnormality in a patient with chromosome 8 inserted into the Y chromosome. It has also failed to detect circular signals in a patient with ring chromosome mosaicism. CONCLUSION: OGM has successfully detected chromosomal structural variations in the four patients and provided assistance for their diagnosis.

A20 haploinsufficiency in a neonate caused by a large deletion on chromosome 6q.

Haploinsufficiency of A20 (HA20) is a rare monogenic disease caused by heterozygous loss-of-function mutations in the tumor necrosis factor alpha-induced protein 3 (TNFAIP3) gene located on chromosome 6q23.3. The majority of disease-causing mutations in most cases of HA20 comprise single nucleotide variations, small insertions, or deletions in TNFAIP3, which result in a premature termination codon and subsequent disruption of its anti-inflammatory role. Large deletions have been reported sporadically. HA20 patients may present with a variety of autoinflammatory and autoimmune features during early childhood; however, cases with neonatal onset are rare. Here, we describe a Chinese neonate presenting with concomitant inflammatory and other syndromic manifestations caused by a 5.15 Mb interstitial deletion in chromosome 6; these deletions affect TNFAIP3. Taken together, the data extend the clinical and genetic spectra of HA20.

Clinical course and genetic analysis of a case of the amniocentesis showing chromosome 6 trisomy mosaicism.

OBJECTIVE: Herein, we present a case of mosaic trisomy 6 detected by amniocentesis. CASE REPORT: Amniocentesis (G-banding) was performed at 17 weeks of gestation; the results were 47,XY,+6[3]/46,XY[12]. Fetal screening ultrasonography showed no morphological abnormalities, and the parents desired to continue the pregnancy. The infant was delivered vaginally at 39 weeks' gestation. The male infant weighed 3002 g at birth with no morphological abnormalities. G-banding karyotype analysis performed on the infant's peripheral blood revealed 46,XY[20]. FISH analysis revealed trisomy signals on chromosome 6 in 1-4 out of 100 cells from the placenta. The single nucleotide polymorphism microarray of the umbilical cord blood revealed no abnormalities. Methylation analysis of umbilical cord blood revealed no abnormalities in PLAGL1. No disorders were observed at one year of age. CONCLUSION: When amniocentesis reveals chromosomal mosaicism, it is essential to provide a thorough fetal ultrasound examination and careful genetic counseling to support the couples' decision-making.

Strong selection signatures for Aleutian disease tolerance acting on novel candidate genes linked to immune and cellular responses in American mink (Neogale vison).

Aleutian disease (AD) is a multi-systemic infectious disease in American mink (Neogale vison) caused by Aleutian mink disease virus (AMDV). This study aimed to identify candidate regions and genes underlying selection for response against AMDV using whole-genome sequence (WGS) data. Three case-control selection signatures studies were conducted between animals (N = 85) producing high versus low antibody levels against AMDV, grouped by counter immunoelectrophoresis (CIEP) test and two enzyme-linked immunosorbent assays (ELISA). Within each study, selection signals were detected using fixation index (FST) and nucleotide diversity (θπ ratios), and validated by cross-population extended haplotype homozygosity (XP-EHH) test. Within- and between-studies overlapping results were then evaluated. Within-studies overlapping results indicated novel candidate genes related to immune and cellular responses (e.g., TAP2, RAB32), respiratory system function (e.g., SPEF2, R3HCC1L), and reproduction system function (e.g., HSF2, CFAP206) in other species. Between-studies overlapping results identified three large segments under strong selection pressure, including two on chromosome 1 (chr1:88,770-98,281 kb and chr1:114,133-120,473) and one on chromosome 6 (chr6:37,953-44,279 kb). Within regions with strong signals, we found novel candidate genes involved in immune and cellular responses (e.g., homologous MHC class II genes, ITPR3, VPS52) in other species. Our study brings new insights into candidate regions and genes controlling AD response.

Whole F8 gene sequencing identified pathogenic structural variants in the remaining unsolved patients with severe hemophilia A.

BACKGROUND: No F8 genetic abnormality is detected in approximately 1% to 2% of patients with severe hemophilia A (HA) using conventional genetic approaches. In these patients, deep intronic variation or F8 disrupting genomic rearrangement could be causal. OBJECTIVES: The study aimed to identify the causal variation in families with a history of severe HA for whom genetic investigations failed. METHODS: We performed whole F8 gene sequencing in 8 propositi. Genomic rearrangements were confirmed by Sanger sequencing of breakpoint junctions and/or quantitative polymerase chain reaction. RESULTS: A structural variant disrupting F8 was found in each propositus, so that all the 815 families with a history of severe HA registered in our laboratory received a conclusive genetic diagnosis. These structural variants consisted of 3 balanced inversions, 3 large insertions of gained regions, and 1 retrotransposition of a mobile element. The 3 inversions were 105 Mb, 1.97 Mb, and 0.362 Mb in size. Among the insertions of gained regions, one corresponded to the insertion of a 34 kb gained region from chromosome 6q27 in F8 intron 6, another was the insertion of a 447 kb duplicated region from chromosome 9p22.1 in F8 intron 14, and the last one was the insertion of an Xq28 349 kb gained in F8 intron 5. CONCLUSION: All the genetically unsolved cases of severe HA in this cohort were due to structural variants disrupting F8. This study highlights the effectiveness of whole F8 sequencing to improve the molecular diagnosis of HA when the conventional approach fails.

Altered chromatin topologies caused by balanced chromosomal translocation lead to central iris hypoplasia.

Despite the advent of genomic sequencing, molecular diagnosis remains unsolved in approximately half of patients with Mendelian disorders, largely due to unclarified functions of noncoding regions and the difficulty in identifying complex structural variations. In this study, we map a unique form of central iris hypoplasia in a large family to 6q15-q23.3 and 18p11.31-q12.1 using a genome-wide linkage scan. Long-read sequencing reveals a balanced translocation t(6;18)(q22.31;p11.22) with intergenic breakpoints. By performing Hi-C on induced pluripotent stem cells from a patient, we identify two chromatin topologically associating domains spanning across the breakpoints. These alterations lead the ectopic chromatin interactions between APCDD1 on chromosome 18 and enhancers on chromosome 6, resulting in upregulation of APCDD1. Notably, APCDD1 is specifically localized in the iris of human eyes. Our findings demonstrate that noncoding structural variations can lead to Mendelian diseases by disrupting the 3D genome structure and resulting in altered gene expression.

Common and rare genetic variants predisposing females to unexplained recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) is a major reproductive health issue with multifactorial causes, affecting 2.6% of all pregnancies worldwide. Nearly half of the RPL cases lack clinically identifiable causes (e.g., antiphospholipid syndrome, uterine anomalies, and parental chromosomal abnormalities), referred to as unexplained RPL (uRPL). Here, we perform a genome-wide association study focusing on uRPL in 1,728 cases and 24,315 female controls of Japanese ancestry. We detect significant associations in the major histocompatibility complex (MHC) region at 6p21 (lead variant=rs9263738; P = 1.4 × 10-10; odds ratio [OR] = 1.51 [95% CI: 1.33-1.72]; risk allele frequency = 0.871). The MHC associations are fine-mapped to the classical HLA alleles, HLA-C*12:02, HLA-B*52:01, and HLA-DRB1*15:02 (P = 1.1 × 10-10, 1.5 × 10-10, and 1.2 × 10-9, respectively), which constitute a population-specific common long-range haplotype with a protective effect (P = 2.8 × 10-10; OR = 0.65 [95% CI: 0.57-0.75]; haplotype frequency=0.108). Genome-wide copy-number variation (CNV) calling demonstrates rare predicted loss-of-function (pLoF) variants of the cadherin-11 gene (CDH11) conferring the risk of uRPL (P = 1.3 × 10-4; OR = 3.29 [95% CI: 1.78-5.76]). Our study highlights the importance of reproductive immunology and rare variants in the uRPL etiology.

Pediatric spinal ependymoma with chromothripsis of chromosome 6: a case report and review of the literature.

BACKGROUND: Ependymomas are the third most common central nervous system tumor in the pediatric population; however, spinal ependymomas in children are rare. Ependymomas affecting the spinal cord most frequently occur in adults of 20-40 years of age. The current World Health Organization classification system for ependymomas is now composed of ten different entities based on histopathology, location, and molecular studies, with evidence that the new classification system more accurately predicts clinical outcomes. CASE PRESENTATION: We present the case of a 16-year-old Caucasian female patient with a history of type 2 neurofibromatosis with multiple schwannomas, meningioma, and spinal ependymoma. Chromosome analysis of the harvested spinal ependymoma tumor sample revealed a 46,XX,-6,+7,-22,+mar[16]/46,XX[4] karyotype. Subsequent OncoScan microarray analysis of the formalin-fixed paraffin-embedded tumor sample confirmed + 7, -22 and clarified that the marker chromosome represents chromothripsis of the entire chromosome 6 with more than 100 breakpoints. Fluorescent in situ hybridization and microarray analysis showed no evidence of MYCN amplification. The final integrated pathology diagnosis was spinal ependymoma (central nervous system World Health Organization grade 2 with no MYCN amplification. CONCLUSION: This case adds to the existing literature of pediatric patients with spinal ependymomas and expands the cytogenetic findings that may be seen in patients with this tumor type. This case also highlights the value of cytogenetics and microarray analysis in solid tumors to provide a more accurate molecular diagnosis.

Common risk alleles for schizophrenia within the major histocompatibility complex predict white matter microstructure.

Recent research has highlighted the role of complement genes in shaping the microstructure of the brain during early development, and in contributing to common allele risk for Schizophrenia. We hypothesised that common risk variants for schizophrenia within complement genes will associate with structural changes in white matter microstructure within tracts innervating the frontal lobe. Results showed that risk alleles within the complement gene set, but also intergenic alleles, significantly predict axonal density in white matter tracts connecting frontal cortex with parietal, temporal and occipital cortices. Specifically, risk alleles within the Major Histocompatibility Complex region in chromosome 6 appeared to drive these associations. No significant associations were found for the orientation dispersion index. These results suggest that changes in axonal packing - but not in axonal coherence - determined by common risk alleles within the MHC genomic region - including variants related to the Complement system - appear as a potential neurobiological mechanism for schizophrenia.

Síndrome de deleção 6q: relato de caso de um achado raro no Amazonas, Brasil / Deletion 6q syndrome: case report of a rare finding in Amazonas, Brazil

Objetivos: Síndrome da deleção 6q é considerada uma anomalia cromossômica rara. Assim, nosso objetivo foi relatar um caso de um menino com essa síndrome, em Manaus/Amazonas. Descrição do caso: Menino com quatro anos de idade que apresenta atraso do crescimento e do desenvolvimento neuropsicomotor, dificuldades de ganho de peso e anormalidades na retina. A análise citogenética do paciente revelou cariótipo com 46, XY, del(6)(q25-qter). Conclusões: Este relato demonstrou a importância das análises citogenéticas para o diagnóstico preciso das anomalias congênitas, pois auxiliam no encaminhamento de tratamentos adequados aos pacientes e na ampliação de conhecimento científico relacionado a essa deleção.

Aims: Deletion 6q syndrome is considered a rare chromosomal anomaly. Thus, our objective was to report a rare case of a boy with 6q deletion syndrome. Case description: 4-year-old boy with delayed growth and neuropsychomotor development, weight gain difficulties and retinal abnormalities. Karyotypic analysis of the patient revealed karyotype 46, XY, del (6) (q25-qter). That is, a deletion in the long arm of one of the chromosome 6, specifically in the distal region of the long arm of the 6q25 band up to the 6qter band. Conclusions: This report demonstrates the importance of cytogenetic analyzes for the accurate diagnosis of congenital anomalies, as they assist in referring appropriate treatments to patients and in expanding scientific knowledge related to this deletion.

Inversiones cromosómicas (anomalías estructurales poco frecuentes) asociadas a fenotipo normal, dudoso y patológico / Chromosomal inversions (Slight structural anomalies) associated to normal, doubtfull and pathological phenotypes

Las inversiones son reordenamientos intracromosómicos originados por dos rupturas en un cromosoma seguidas de la reinserción del fragmento rotado en 180º. Dependiendo si involucra o no al centrómero pueden ser pericén tricas o paracéntricas. La incidencia es 0.09 a 0.49/1.000. Las inversiones son rearreglos estructurales aparentemente equilibrados, por lo que la mayoría de los individuos portadores tienen fenotipos normales y una minoría tienen fenotipos patológicos (probablemente por alteración en la secuencia de genes o variación en la función de éstos por efectos de cambio de posición). Se presentan tres casos de inversiones detectas por la técnica de Bandeo G y confirmadas por Hibridación In Situ Fluorescente (FISH). Caso 1: INVERSION PARACENTRICA FAMILIAR DEL CROMOSOMA 13 ASOCIADA A RETRASO MENTAL Y DISMORFIAS. El exhaustivo análisis del árbol genealógico y el estudio cromosómico al mayor número posible de individuos permitió confirmar la asociación inversión/fenotipo patológico en este grupo familiar. 13 de 17 miembros son portadores de inv(13)(q31q32)inh.ish inv(13)(q31q32) (wcp13+). Caso 2: INVERSION PARACENTRICA DEL CROMOSOMA 6 DE NOVO EN RECIEN NACIDO CON RETRASO MADURATIVO GLOBAL Y RETRASO DEL CRECIMIENTO INTRAUTERINO. En este caso no es posible adjudicar que, el fenotipo afectado se deba a la inversión. Cariotipo: 46,XY,add(6)(q21)dn.ish inv(6)(q21q27)(wcp6+). Caso 3: INVERSION PERICENTRICA DEL CROMOSOMA 12 EN OVODONANTE. Dicha inversión no parece tener efecto sobre el fenotipo, ya que es una paciente con coeficiente intelectual normal y no presenta malformaciones congénitas. Cariotipo: 46,XX,inv(12)(p12q14).ish inv(12) (p12q14)(wcp12+). Este reporte de casos muestra los tres fenotipos posibles de una inversión: patológico, dudoso y normal. Es el primer reporte de una inv(13) que confiera fenotipo patológico.

The inversions are intrachromosomal rearrangements which occur when a single chromosome undergoes two breaks and the region between it's rotates 180 degrees before rejoining. Depending on whether or not it include the centromere, they can be pericentric or paracentric. The incidence is 0.09 to 0.49/1,000. The inversions are apparently balanced structural rearrangements, so the most of the carrier individuals show normal phenotypes and a minority have pathological phenotypes (probably due to variation in their function due to changes in position). Three cases of inversions detected by the G Banding technique and confirmed by Fluorescence In Situ Hybridization (FISH) are presented. Case 1: FAMILIAL PARACENTRIC INVERSION OF CHROMOSOME 13 ASSOCIATED WITH MENTAL RETARDATION AND DISMORPHIA. The exhaustive analysis of the pedigree and the chromosomal study to the greatest possible number of individuals confirmed the inversion/pathological phenotype association in this family group. 13 of 17 members are carriers of inv(13)(q31q32)inh.ish inv(13)(q31q32)(wcp13+). Case 2: PARACENTRAL INVERSION DE NOVO OF CHROMOSOME 6 IN NEWBORN WITH GLOBAL MATURITY DELAY AND DELAY OF INTRAUTERINE GROWTH. In this case it is not possible to adjudge that, the affected phenotype is due to the inversion. Karyotype: 46,XY,add(6)(q21)dn.ish inv(6)(q21q27)(wcp6+). Case 3: PERICENTRIC INVERSION OF CHROMOSOME 12 IN OVODONANT. This inversion does not seem to have an effect on the phenotype, since it is a patient with normal IQ and does not present congenital malformations. Karyotype: 46,XX,inv(12)(p12q14).ish inv(12) (p12q14)(wcp12+). This case report shows the three possible phenotypes of an inversion: pathological, questionable and normal. It is the first report of an inv(13) that confers pathological phenotype. Key words: chromosomal inversion, G Banding, phenotype, structural rearrangement, fluorescence in situ hybridization.

Analysis of chromosomal abnormalities by CGH-array in patients with dysmorphic and intellectual disability with normal karyotype / Análise de anomalias cromossômicas por CGH-array em pacientes com dismorfias e deficiência intelectual com cariótipo normal

ABSTRACT Objective To investigate chromosomal abnormalities by CGH-array in patients with dysmorphic features and intellectual disability with normal conventional karyotype. Methods Retrospective study, carried out from January 2012 to February 2014, analyzing the CGH-array results of 39 patients. Results Twenty-six (66.7%) patients had normal results and 13 (33.3%) showed abnormal results - in that, 6 (15.4%) had pathogenic variants, 6 (15.4%) variants designated as uncertain and 1 (2.5%) non-pathogenic variants. Conclusion The characterization of the genetic profile by CGH-array in patients with intellectual disability and dysmorphic features enabled making etiologic diagnosis, followed by genetic counseling for families and specific treatment.

RESUMO Objetivo Avaliar microalterações cromossômicas por CGH-array em portadores de dismorfias e deficiência intelectual com cariótipo normal. Métodos Estudo retrospectivo, realizado no período de janeiro de 2012 a fevereiro de 2014, analisando os resultados de CGH-array de 39 pacientes. Resultados Apresentaram resultados normais 26 (66,7%) pacientes; 13 (33,3%) tiveram resultados alterados, a saber: 6 (15,4%) com variantes patogênicas, 6 (15,4%) com variantes pertencentes à categoria designada como incerta, e 1 (2,5%) com variantes não patogênicas. Conclusão A caracterização do perfil genético por CGH-array nos pacientes com deficiência intelectual e dismorfias possibilitou complementar o diagnóstico etiológico, permitindo a realização do aconselhamento genético para as famílias e tratamento específico.

Un caso de deleción parcial 1p36. 1 y trisomía parcial 6p diagnosticadas por cariotipo / A case of partial 1p36. 1 deletion and partial trisomy 6p diagnosed by karyotype

La deleción de la región cromosómica 1p36 es una de las anomalías subteloméricas más frecuentes y causa rasgos dismórficos distintivos. Por otro lado, la trisomía distal del brazo corto del cromosoma 6 es una anormalidad cromosómica poco frecuente de fenotipo variable. Objetivo: Presentar el caso de un paciente con ambas alteraciones cromosómicas, y resaltar la vigencia e importancia del cariotipo como herramienta diagnóstica en dismorfología. Caso clínico: Lactante de 2 meses de edad con múltiples anomalías craneofaciales, hemangioma en la nuca, fosita sacra, acortamiento rizomélico, pies y manos pequeños, criptorquidia unilateral izquierda e hipotonía. Además, antecedente de restricción del crecimiento intrauterino. Producto del octavo embarazo de una mujer G8A7C1 de 28 años. Con estos hallazgos inespecíficos en el fenotipo se solicitó cariotipo que mostró una deleción parcial de 1p36.1 y una trisomía parcial de cromosoma 6p. Conclusión: El cariotipo convencional sigue siendo una herramienta importante para el etiológico en pacientes con anomalías congénitas (múltiples), mostrando en este caso una deleción parcial de 1p36.1 y una trisomía parcial de cromosoma 6p, alteraciones cromosómicas estructurales.

The deletion of chromosomal region 1p36 is one of the most common sub-telomeric microdeletion syndromes and has distinctive dysmorphic features. On the other hand, partial trisomy of the short arm of chromosome 6 is a rare chromosomal abnormality with a variable phenotype. Objective: To report a case with both chromosome abnormalities, and to highlight the importance of the karyotype as a diagnostic tool in dysmorphology. Clinical case: The case of is presented of a two month-old infant with several craniofacial anomalies, neck haemangioma, sacral pit, rhizomelic shortening, small hands and feet, left unilateral cryptorchidism, and hypotonia. The infant also suffered intrauterine growth restriction and is the product of the eighth pregnancy of a 28 years old woman. Due to the unspecific findings in phenotype, a karyotype was requested, which showed a partial deletion of 1p36.1 and a partial trisomy of chromosome 6. Conclusion: The development of new techniques in molecular biology has improved diagnostic possibilities in medical genetics. However, the traditional karyotype remains as an important diagnostic tool in patients with multiple congenital anomalies.

Chromosome 6q deletion: report of a new case and review of the literature

Os autores descrevem um novo caso de monossomia parcial do braço longo do cromossomo 6[46,XY,del(6)(q22 qter)]. A ocorrência de retardo psicomotor severo é esperada em funçäo do paciente apresentar um dos maiores segmentos deletados além da banda 6q25.

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

Late onset autosomal dominant cerebellar ataxia: a family description and linkage analysis with the HLA system

Descreve-se uma família afetada por forma autossômica dominante de ataxia cerebelar de início tardio (acima dos 20 anos). Oito membros da família säo estudados e dados de outros quatro afetados pela doença foram obtidos por anamnese. A média de idade de início da doença foi 37,1 ñ 5,4 anos (27-47 anos). O quadro clínico consistia basicamente de síndrome cerebelar de caráter lentamente progressivo, sem ocorrência concomitante de sinais ou sintomas decorrentes de envolvimento de outros sistemas. Estudo tomográfico computadorizado mostra atrofia cerebelar difusa com relativa preservaçäo do tronco cerebral e das estruturas supratentoriais. Estudos neurofisiológicos (neuroconduçäo motora/sensitiva, potenciais evocados visuais e auditivos) foram normais. Vinte e seis pessoas da família foram tipados para antígenos de histocompatibilidade HLA. Escores lod foram calculados utilizando programa de computador denominado LINKMAP. Ligaçäo estreita com o sistema HLA nesta família foi excluida - 0=0,02, z=(-2,17) - e a análise global dos escores lod sugerem que o gene mutante nesta família näo se localiza no cromossomo 6