Genetic analysis of a Fra(16)(q22) fragile site in a female with secondary infertility / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a Fra(16)(q22)/FRA16B fragile site in a female with secondary infertility.@*METHODS@#The 28-year-old patient was admitted to Chengdu Women's and Children's Central Hospital on October 5, 2021 due to secondary infertility. Peripheral blood sample was collected for G-banded karyotyping analysis, single nucleotide polymorphism array (SNP-array), quantitative fluorescent polymerase chain reaction (QF-PCR) and fluorescence in situ hybridization (FISH) assays.@*RESULTS@#The patient was found to harbor 5 mosaic karyotypes involving chromosome 16 in a total of 126 cells, which yielded a karyotype of mos 46,XX,Fra(16)(q22)[42]/46,XX,del(16)(q22)[4]/47,XX,del(16),+chtb(16)(q22-qter)[4]/46,XX,tr(16)(q22)[2]/46,XX[71]. No obvious abnormality was found by SNP-array, QF-PCR and FISH analysis.@*CONCLUSION@#A female patient with FRA16B was identified by genetic testing. Above finding has enabled genetic counseling of this patient.

Genetic analysis of an individual with a fragile site at 16q22 / 中华医学遗传学杂志

OBJECTIVE@#To analyze a patient with infertility and a fragile site found at 16q22 by using cytogenetic methods.@*METHODS@#Peripheral blood sample was taken from the patient and subjected to chromosomal karyotyping and single nucleotide polymorphism microarray (SNP-array) analysis.@*RESULTS@#The patient was found to be a mosaicism for a fragile site at 16q22, which has a variable morphology and cannot be induced by folic acid treatment. No abnormality was found by SNP-array analysis.@*CONCLUSION@#A rare fragile site, which can be induced without folic acid treatment, has been identified at 16q22. The strategy of assisted reproduction for such individuals is yet to be explored.

The Expression of Folate Sensitive Fragile Sites in Patients with Bipolar Disorder

PURPOSE: Genetic factors are known to be important in the etiology of bipolar disorder (BD). The fragile sites (FSs) are a very interesting subject for the study of clinical disorders. The aim of this study was to evaluate fragile sites seen in patients with bipolar disorder and find a correlation between some fragile sites and bipolar disorder. PATIENTS AND METHODS: The frequencies of folate sensitive FSs were compared in short-term whole blood cultures from bipolar patients and from normal individuals. RESULTS: The rate of FS expression in the patients was considerably higher than in the controls (p < 0.001). Several chromosome regions including 1p36, 1q21, 1q32, 3p25, 7q22, 7q32, 11q23, 12q24, 13q32, 14q24, Xp22 and Xq26 were represented considerably more often in the patients than in the controls (p value between 0.001 to 0.036). Among these FSs, the sites 1p36, 1q21, 3p25, 7q22, 7q32, and 14q24 were not observed in other studies. CONCLUSION: These regions can be the most active of hot spots in the genomes of bipolar patients, and may harbor important genes associated with BD.

Expression and identification of folate-sensitive fragile sites in British Suffolk sheep (Ovis aries).

An investigation to understand the dynamics and biological significance of fragile site expression, and identification of 5-fluorodeoxyuridine (FUdR) induced chromosomal gaps/breaks, were carried out in an experimental flock of 45 Suffolk sheep. The statistical comparison revealed, highly significant variation in the frequency of chromosomal fragile site expression between control and FUdR cultures. Mean (+/- S.D.) values for cells with gaps and breaks, or aberrant cell count (AC), and the number of aberrations (NoA) per animal were 2.02 +/- 0.34, 2.42 +/- 0.48, 13.26 +/- 0.85 and 21.87 +/- 1.88 (P lessthan 0.01) in control and FUdR cultures, respectively. The comparison of age revealed nonsignificant variation between control and FUdR cultures. The G-band analysis of fragile site data revealed gaps in 29 autosomal and two X-chromosomal bands in the control cultures, whereas FUdR treated cultures scored 78 unstable bands in autosomes of which 56 were significantly fragile. X-chromosomes expressed breaks and gaps in six G-negative bands and five of them (Xq13, Xq15, Xq17, Xq24 and Xq26) were significantly fragile. The distribution comparison of autosomal fragile sites between sex groups did not reveal any significant variation. Female X-chromosomes were significantly more fragile than the male X-chromosomes. The distribution comparison for age groups (lambs versus adults) revealed significantly higher number of fragile bands in adults. Comparison of published data on reciprocal translocations in sheep with the fragile-site data obtained in this study indicated that the break sites of both phenomena were correlated. Similarities were also found between fragile sites and breakpoints of evolutionary significance in family Bovidae.

Molecular approach of the fragile chromosomal region Xq31-34 in cattle (Bos taurus) by microdissection and DOP-PCR / Aproximação molecular da região cromossômica frágil Xq31-34 em bovinos (Bos taurus) utilizando microdissecação cromossômica e DOP-PCR

Fragile sites (FS) are chromosomal regions where the normal compactation of chromatine is not observed. FRAXA (Fra Xq27.3, X sexual chromosome) is one of the most studied FS in humans. FRAXA is an expansion of the trinucleotide CGG located in the gene FMR-1. In cattle, sites of chromosomal fragility were reported in BTAX, associated with different pathologies and fertility impairment. Chromosomal microdissection has became a valuable tool for isolating chromatine fragments. In this work, it was combined the chromosomal microdissection technique with DOP-PCR in order to carry out a molecular analysis of the fragile chromosomal region BTAXq31-34. In that region, polymorphic DNA-RAPD sequences (GC rich) are present and sequences of the gene FMR-1 are missing. The results showed the usefulness of the microdissection-DOP-PCR technique for molecular characterization of fragile chromosomal sites in cattle.

Os sítios frágeis (FS) são regiões de cromossomo onde a compactação normal da cromatina não é realizada. O FRAXA (Fra Xq27.3, cromossomo sexual X) é um dos FS mais estudados em seres humanos. O FRAXA apresenta expansão do trinucleotídeo CGG localizado no gene FMR-1. Em bovinos, existem estudos informando sobre fragilidade cromossômica em BTAX associada com diversas patologias e alterações na fertilidade. A microdissecação cromossômica é uma valiosa técnica para isolar fragmentos de cromatina. Neste trabalho, combinou-se a técnica de microdissecação de cromossomo com DOP-PCR para executar a análise molecular da região do sitio frágil cromossômico BTAXq31-34. Naquela região estão presentes seqüências do polimorfo DNA-RAPD (rico em GC), em que as seqüências do gene FMR-1 estão ausentes. Os resultados mostram a utilidade da técnica de microdissecação-DOP-PCR para a caracterização molecular de sítios frágeis cromossômicos em bovinos.

Loss expression of active fragile sites genes associated with the severity of breast epithelial abnormalities / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>WWOX and FHIT are two candidate tumor suppressor genes located in active fragile sites, the damage of which has been associated with the development of breast cancer. The association of the expression of these genes and the development of breast cancer has not been fully explored. We evaluated mRNA and protein expression of WWOX and FHIT in breast tissue with normal histological appearances, atypical ductal hyperplasia, ductal carcinoma in situ, and invasive cancer to see if a progressive decline in expression was present.</p><p><b>METHODS</b>Reverse transcription-polymerase chain reaction and Western blotting were used to evaluate the specimens for mRNA and protein expression, including 28 specimens with normal tissue, 28 specimens with atypical ductal hyperplasia, 33 specimens with ductal carcinoma in situ, and 51 specimens with invasive ductal carcinoma.</p><p><b>RESULTS</b>Compared with in situ and invasive cancer specimens, both normal and atypical hyperplasia specimens had greater rates of detectable mRNA (WWOX rate ratio = 2.95, 95% CI 1.24 - 7.08; FHIT rate ratio = 4.58, 95% CI 1.82 - 11.81) and Western blotting detectable protein (WWOX rate ratio = 4.12, 95% CI 1.63 - 10.73; FHIT rate ratio = 3.76, 95% CI 1.44 - 10.06). For both proteins, differences between normal and atypical hyperplasia specimens and between in situ and invasive carcinoma specimens were explainable by chance (P > 0.05 for each analysis). Within each histological category, differences among fractions of specimens showed that FHIT and WWOX mRNA and protein expression were explainable by chance (P > 0.05 for each analysis).</p><p><b>CONCLUSION</b>Expression of FHIT and WWOX decreases along with breast tissue progress from a normal histological appearance to atypical ductal hyperplasia, in situ cancer, and the final invasive cancer.</p>

Molecular cloning and preliminary analysis of a fragile site associated gene / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To analyze the molecular coining of a fragile site-associated gene.</p><p><b>METHODS</b>Genomic Chinese hamster ovary (CHO) DNA library was constructed using high molecular weight CHO DNA partially digested with MboI restriction enzyme from cultured CHO cells. Screening of genomic DNA library followed the established procedures. Genomic CHO in the positive clones was sequenced. Appropriate primers were designed for the reverse transcriptase-polymerase chain reactions (RT-PCR). The RT-PCR products were cloned into a pCRII TOPO vector and confirmed by DNA sequencing. Antibodies were prepared using synthetic peptides as antigens by immunizing the rabbits. Immunohistochemical analyses were performed to evaluate the expression of the novel gene in different tissues.</p><p><b>RESULTS</b>To investigate the molecular mechanism underlying the initial events of mdr1a amplification, we cloned 1q31 fragile site DNA. Strikingly, we found that this fragile site contained a novel gene which was designated as a fragile site-associated (FSA) gene. FSA encoded an unusually large mRNA of approximately16 kb. Full-length human FSA cDNA was cloned. FSA mRNA was expressed in many cultured cells and tissue types. Immunohistochemical analyses also revealed an expression pattern of the encoded proteins in postmitotic, well-differentiated epithelial compartments of many organs, including colon, mammary glands, ovary, prostate, and bladder.</p><p><b>CONCLUSION</b>FSA plays an important role in regulating mammalian epithelial cell growth and differentiation.</p>

Laboratorial diagnosis of fragile-X syndrome: experience in a sample of individuals with pervasive developmental disorders

A síndrome do cromossomo X frágil (SXF) é uma doença genética freqüente associada a distúrbios do desenvolvimento neurológico, incluindo dificuldades de aprendizagem, retardo mental, problemas comportamentais e distúrbios invasivos do desenvolvimento (autismo e correlatos). Estudamos uma amostra de 82 indivíduos (69 homens e 13 mulheres) apresentando distúrbios invasivos do desenvolvimento, utilizando três técnicas para o diagnóstico da SXF. A análise citogenética detectou a presença do sítio frágil em quatro homens, porém apenas um deles com percentagem consistente. O estudo molecular baseado na técnica da PCR foi inconclusivo para a maioria das mulheres (92,3%), as quais foram posteriormente submetidas a análise por Southern blotting, e para um homem (1,4%), excluindo a mutação FRAXA nos demais homens (98,6%). O teste molecular usando a técnica de Southern blotting confirmou apenas um caso positivo (1,2%) em um indivíduo do sexo masculino. Tais resultados mostraram que a técnica de Southern blotting para análise da mutação FRAXA apresenta a melhor sensibilidade e especificidade para o diagnóstico da SXF, mas também valida a técnica da PCR como um teste confiável para seu rastreamento.

Rechercher du syndrome de l'x fragile par hybridation moleculaire chez 29 familles de retard mental hereditaire

The diagnosis of the fragile X syndrome was based on the detection of the fragile site by cytogenetic analysis, which is not completely reliable. Since 1991, a new diagnosis test have been described which detect mutation in the FMR-1 gene responsible for the mental retardation and the various somatic signs. In the present study, we show by Southern Blot and hybridation that 3 from 29 families had fragile X syndrome. Three profiles have been identified: normal, premutation and full mutation. We propose the use of the molecular approach to detect systematically the fragile Xmutation in boys or girls with unexplained mental retardation and for prenatal diagnosis

Fragile-x marker among patients having numerical [autosomal and sex] chromosomal aberrations

As fragile-X syndrome is the 2nd most common chromosomal abnormality causing mental retardation, and aiming to investigate its concurrent occurrence with the most common numerical and sex chromosomal aberration syndromes, this study was conducted to investigate this issue in 43 subjects [Down syndrome, 20, and Klinefelter, 14, and Turner, 9]. Results showed that overall, fra-[X] marker was observed in only one of the Klinefelter syndrome subject and in none of the Down syndrome or Turner syndrome subjects. This adolescent case showed increased urinary homocystine level, compared with other members of Klinefelter group. This metabolic finding may explain his aberrant symptomatology

Chromosomal break points in irradiated and ethyl methane sulphonate treated leucocytes of patients with Down syndrome.

Frequencies of chromosomal damage in the peripheral leucocytes of patients with Down syndrome, on exposure to gamma rays (2Gy) or ethyl methane sulphonate (EMS, 1x 10(-4) M), were assessed. Analysis of break points in the chromosomes of irradiated cells revealed a non-random occurrence. Six of the break points observed in EMS-treated cells were found to overlap with those recorded in irradiated cells. Thirteen break points observed were found to correlate with the location of cancer-specific break points and four of these coincided with the bands where oncogenes have been located. Two break points were localised to the same bands as that of known heritable fragile sites.

Familial fragile secondary constriction on chromosome 2 (2q11) with unusual features and psychomotor retardation.

A child with fragile secondary constriction 2q11 associated with unusual clinical features and psychomotor retardation is described. The pathogenetic significance of this fragile site still remains unclear, and heterogeneity of clinical manifestations is not well understood.

Correlation of fragile sites and bleomycin induced chromosome break points.

Bleomycin (Blm) induced break points in human chromosome preparations were compared with the known fragile sites. A total of 136 breaks were observed from 100 well spread G-banded plates (1.3 bps/cell). These correspond to a total of 57 break prone sites. Of these 57 sites, 24 correspond to the known fragile sites, 5 to sites of protooncogenes and neoplasia, 26 sites correspond to more than one known site of fragility, protooncogene, neoplasia or reciprocal translocation sites, and 2 unknown sites. The findings suggest that fragile sites, either commonly expressed or induced, might be a predisposing factor for chromosome aberrations in human. The expression of fragile sites induced by Blm and their correlation with the known cancer chromosome break points, oncogenes and reciprocal translocation, suggest that the fragile sites are prone to mutagenic action.