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PubMedDate not supplied

Cytomorphology of lipomatous tumors of soft tissue.

OBJECTIVE: To evaluate the cytomorphologic features of benign and malignant lipomatous tumors of soft tissue on fine needle aspirates (FNA) and determine if the variants of liposarcoma could be identified. STUDY DESIGN: FNA of histologically documented benign (51 cases) and malignant (39 cases) lipomatous tumors were reviewed. Twenty-six of the 51 FNA from lipomas and 34 of the 39 FNA from malignant lipomatous tumors were satisfactory for evaluation. RESULTS: FNA from 26 cases of lipomas were cellular, with lobulated, fibroadipose tissue. Thin and thick capillaries were seen in 92% and 65% of cases, though a chicken wire vascular pattern was seen in only 4 cases (15%). A cytodiagnosis of liposarcoma could be made in 23 cases (88%), and these could be further subtyped into well-differentiated (4 cases), myxoid (8), pleomorphic (4), round cell (3) and liposarcoma, ?type (4). Only 50% of the well-differentiated liposarcomas, 3 of the 10 pleomorphic liposarcomas and 8 of the 17 myxoid liposarcomas were diagnosed as such on FNA. Cytologic diagnosis of the remaining 9 cases of myxoid liposarcoma were pleomorphic liposarcoma (1); liposarcoma, ?type (3); malignant mesenchymal tumor (1); suspicious for malignancy (2); and benign (2). There were no false positives, but there were 3 false negative cases (1 well-differentiated and 2 myxoid liposarcoma). CONCLUSION: Lipomas can be diagnosed readily. Arborizing vessels can be seen in lipomas and should be interpreted with caution. Subclassification of liposarcomas on FNA is possible but not very reliable. Myxoid liposarcomas pose a problem, and aspirates from them can mimic a wide range of morphologic subtypes. The role of FNA in identification of variants of liposarcoma is limited.

Adipocytes↗

PubMed2005

Excitement and confusion on chromosome 6q: the challenges of neuropsychiatric genetics in microcosm.

The search for genes that are implicated in the pathogenesis of schizophrenia (SCZ), bipolar disorder (BPD) and other complex neuropsychiatric phenotypes has yielded a plethora of positive findings, but has also engendered a substantial degree of confusion. Exciting findings include positive linkage results in a number of chromosomal regions and the identification of several genes that have been associated with SCZ and to a lesser extent with BPD. Confusing aspects include the difference between studies in localization of linkage peaks in the same chromosomal regions, raising the possibility that these regions may harbor more than one gene, the fact that positive linkage findings as well as associated genes appear in several cases to be shared by more than one disorder, and the failure to identify thus far the precise pathogenic variants in associated genes. Recent findings of linkage and association studies on chromosome 6q illustrate the current status of neuropsychiatric genetics in intriguing microcosm. Positive findings from linkage and association studies are reviewed in order to identify approaches that may help to settle apparent contradictions and allow an interpretation of the results that may prove useful in application to findings from other chromosomal regions. Not only SCZ and BPD but also other psychiatric and neurological phenotypes are considered. Taking a topographic approach, we identify five foci of positive findings on chromosome 6q and suggest that each may harbor gene(s) that confer susceptibility to SCZ or BPD or may modify their onset or clinical course. We further suggest that in searching for these genes the possibility that they may be implicated in more than one disorder should be taken into account. We also discuss the potential contribution of rare genetic variants identified in homogeneous, isolated populations to the subsequent identification of common variants in the same gene that contribute to disease susceptibility in outbred populations.

Bipolar Disorder↗

PubMed2026

Pan-Cancer Quantification of Driver Alteration Transmission Across Molecular Layers Reveals Limited Propagation to Protein Abundance.

Precision oncology relies primarily on DNA-level alterations for therapeutic decisions, but the extent to which driver mutations propagate to protein abundance has not been systematically evaluated. Here, I developed a regression-based transmission score (TS_R 2) to quantify driver alteration signal propagation across DNA, mRNA, and protein layers. Applying this framework to matched genomic, transcriptomic, proteomic, and phosphoproteomic data from 754 Clinical Proteomic Tumor Analysis Consortium (CPTAC) tumors across seven cancer types, I analyzed 86 driver gene-cancer type pairs, of which 83 were evaluable for the full two-layer transmission score. I employed covariate-adjusted regression for each molecular transition, assessing significance via permutation testing (n = 1000). Mixed-effects modeling then partitioned gene-intrinsic from cancer-type-dependent effects. Only 5 of 83 evaluable pairs (6%) demonstrated high transmission (TS_R 2 > 0.05), with receptor tyrosine kinases (EGFR, FGFR2) exemplifying this class. The primary bottleneck occurred at the mutation-mRNA transition, not mRNA-protein translation. Gene identity accounted for 49% of transmission efficiency variance, nearly double the contribution of cancer type (29%). Copy number alterations transmitted signals 13.8-fold more efficiently than point mutations, and truncating mutations showed higher transmission than missense variants (Wilcoxon p = 0.005). Microsatellite instability attenuated mRNA-protein transmission in UCEC and COAD. These findings demonstrate that many driver alterations show limited propagation to protein abundance. This challenges DNA-only interpretations in precision oncology and provides a framework for integrated functional driver prioritization.

Humans↗

PubMed2000

Polymerization of deoxy-sickle cell hemoglobin in high-phosphate buffer.

Deoxy-sicklecell hemoglobin (HbS) polymerizes in 0.05 M phosphate buffer to form long helical fibers. The reaction typically occurs when the concentration of HbS is about 165 mg/ml. Polymerization produces a variety of polymorphic forms. The structure of the fibers can be probed by using site-directed mutants to examine the effect of altering the residues involved in intermolecular interactions. Polymerization can also be induced in the presence of 1.5 M phosphate buffer. Under these conditions polymerization occurs at much lower concentrations (ca. 5 mg/ml), which is advantageous when site-directed mutants are being used because only small quantities of the mutants are available. We have characterized the structure of HbS polymers formed in 1.5 M phosphate to determine how their structures are related to the polymers formed under more physiological conditions. Under both sets of conditions fibers are the first species to form. At pHs between 6.7 and 7.3 fibers initially form bundles and then crystals. At lower pHs fibers form macrofibers and then crystals. Fourier transforms of micrographs of the polymers formed in 1.5 M phosphate display the 32- and 64-A(-1) periodicity characteristic of fibers formed in 0.05 M phosphate buffer. The 64-A(-1) layer line is less prominent in Fourier transforms of negatively stained fibers formed in 1.5 M phosphate possibly because salt interferes with staining of the fibers. However, micrographs and Fourier transforms of frozen hydrated fibers formed in high and low phosphate display the same periodicities. Under both sets of reaction conditions HbS polymers form crystals with the same unit cell parameters as Wishner-Love crystals (a = 64 A, b = 185 A, c = 53 A). Some of the polymerization intermediates were examined in the frozen-hydrated state in order to determine whether their structures were significantly perturbed by negative staining. We have also carried out reconstructions of the frozen-hydrated fibers in high and low phosphate to compare their molecular coordinates. The helical projection of the reconstructions in low phosphate shows the expected 14-strand structure. In high phosphate the 14-strand fibers are also formed and their molecular coordinates are the same (within experimental error) as those of fibers formed in 0.05 M phosphate. In addition, the reconstructions of high-phosphate fibers reveal a new minor variant of fiber containing 10 strands. The polymerization products in 1.5 M phosphate buffer were generally indistinguishable from those formed in 0.05 M phosphate buffer. Micrographs of frozen hydrated specimens have facilitated the interpretation of previously published micrographs using negative staining.

Biopolymers↗

PubMed2001

MR imaging of the foot and ankle: patterns of bone marrow signal abnormalities.

Diagnosis of marrow disorders of the foot and ankle is among the more challenging aspects of MR interpretation. Evaluation of normal and abnormal bone marrow with regard to pattern, distribution, and signal characteristics on different sequences often allows a specific diagnosis. This pictorial review illustrates MR imaging findings of normal variants of bone marrow of the foot and ankle, and the varied responses of bone marrow to trauma, stress, or disease.

Adolescent↗

PubMed2004

Xanthine dehydrogenase and aldehyde oxidase impact plant hormone homeostasis and affect fruit size in 'Hass' avocado.

The contribution of xanthine dehydrogenase (XDH, EC 1.1.1.204) to fruit size was investigated using the normal and small-fruit variants of Persea americana Mill. cv. 'Hass'. Inhibition of XDH by treatment of normal fruit, in the linear phase of growth (phase II), with allopurinol (Allo) arrested fruit growth. Adenine (Ade), a less effective inhibitor of this enzyme, also arrested fruit growth when applied in phase II and slowed fruit growth when applied in phase III. A time-course study on the activity of XDH in mesocarp tissue from normal and small fruit showed that maximum activity occurred late in phase II and that the peak in activity was absent in mesocarp of the small fruit. Feeding Ade to growing fruit in phase III caused a transient decline in fruit growth (measured as change in fruit length). Thereafter, growth resumed although fruit size was irreversibly affected. Treatment of fruit with Ade and Ade-containing cytokinins altered activity of another molybdenum enzyme, aldehyde oxidase (EC 1.2.3.1). Cytokinin oxidase was induced by cytokinin and auxin. Purine catabolism via hypoxanthine/xanthine was operative in normal fruit and in mesocarp from the small-fruit variant and as expected, Allo treatment caused accumulation of xanthine and adenine. In the absence of an increase in XDH during growth of the small-fruit phenotype, low levels of Ade were interpreted as resulting from respiration-enhanced adenylate depletion. Stress and/or pathogen induction of the alternative oxidase pathway is proposed as a possible cause.

Adenine↗

PubMed1972

Patterns of Genetic Differentiation in the Slender Wild Oat Species Avena barbata.

Allozyme frequencies at five enzyme loci were determined for 14 California populations of Avena barbata, a species introduced to California from the Mediterranean Basin during the colonization of North America. Allelic frequencies at these loci were also determined in Mediterranean collections of this species. The pattern of divergence of the California populations from the ancestral gene pool was not random and was strongly correlated with environment; thus, the pattern is not in accord with the hypothesis that most electrophoretically detectable variants are adaptively neutral. Rates of gene substitution in California were also not in accord with the neutrality hypothesis. The observations are, however, compatible with predictions of Neo-Darwinian evolutionary theory. We interpret these observations to indicate that natural selection plays a major role in determining the unique patterns of distribution of genetic variability in the slender wild oat in California.

Journal Article↗

PubMed1985

Structure of proteins with single-site mutations: a minimum perturbation approach.

A large number of mutant proteins with single amino acid substitutions are now being produced. The ability to predict the structural changes expected from such mutations would aid greatly in the efficient utilization of the mutagenic techniques and in the interpretation of the changes in stability and function that result. A minimum perturbation approach is suggested as a first step in such structural predictions and is tested by application to a recently isolated variant of the hemagglutinin glycoprotein. The agreement between the predicted structure and that inferred from the x-ray refinement is encouraging and provides support for the proposed modeling procedure.

Hemagglutinin Glycoproteins, Influenza Virus↗

PubMed1994

Cellular hemangioma and angioblastoma of the spine, originally classified as hemangioendothelioma. A confusing diagnosis.

STUDY DESIGN: The authors report two cases of vascular tumors of the spine, classified originally as benign and malignant hemangioendothelioma, and after revision, as cellular hemangioma and angioblastomatosis, respectively. OBJECTIVES: Problems in interpretation of the confusing term hemangioendothelioma and treatment modalities for vascular tumors of the spine are discussed. SUMMARY OF BACKGROUND DATA: Hemangioendothelioma is a confusing term and is often used to cover bewilderment at the biological behavior of a vascular tumor. Its spectrum ranges, depending the references used, from benign to malignant and can mistakenly include benign lesions like cellular hemangioma and angioblastoma (solitary and multicentric). METHODS: Of two patients with a cellular tumor of the spine, the clinicopathologic data and modes of treatment are reviewed. The relevant literature is discussed. RESULTS: In the first case, the diagnosis of benign cellular hemangioendothelioma was changed to cellular hemangioma. In the second case, the original diagnosis of malignant hemangioendothelioma with metastasis to liver and lungs was changed to angioblastomatosis, most probably benign. In both cases, a correct interpretation of the initial diagnosis or proper diagnosis would have influenced the mode of treatment. CONCLUSION: Avoid the confusing term hemangioendothelioma. If a vascular lesion is benign, it should be classified as a variant of hemangioma. If malignant as angiosarcoma, use a separate category, in which lesions like angioblastoma and angioblastomatosis can be put until their nature has been clarified.

Adult↗

PubMedDate not supplied

CartoDraw: a fast algorithm for generating contiguous cartograms.

Cartograms are a well-known technique for showing geography-related statistical information, such as population demographics and epidemiological data. The basic idea is to distort a map by resizing its regions according to a statistical parameter, but in a way that keeps the map recognizable. In this study, we formally define a family of cartogram drawing problems. We show that even simple variants are unsolvable in the general case. Because the feasible variants are NP-complete, heuristics are needed to solve the problem. Previously proposed solutions suffer from problems with the quality of the generated drawings. For a cartogram to be recognizable, it is important to preserve the global shape or outline of the input map, a requirement that has been overlooked in the past. To address this, our objective function for cartogram drawing includes both global and local shape preservation. To measure the degree of shape preservation, we propose a shape similarity function, which is based on a Fourier transformation of the polygons' curvatures. Also, our application is visualization of dynamic data, for which we need an algorithm that recalculates a cartogram in a few seconds. None of the previous algorithms provides adequate performance with an acceptable level of quality for this application. In this paper, we therefore propose an efficient iterative scanline algorithm to reposition edges while preserving local and global shapes. Scanlines may be generated automatically or entered interactively to guide the optimization process more closely. We apply our algorithm to several example data sets and provide a detailed comparison of the two variants of our algorithm and previous approaches.

Algorithms↗

PubMed1985

Hemoglobin Hofu associated with beta 0-thalassemia.

A mild anemia (hemoglobin 9 g/dl) was found in a patient from Seville (Spain) with marked morphological abnormalities in the peripheral blood smear. The red cell osmotic fragility showed a mild resistance curve with a mean cell fragility (MCF) of 0.375% NaCl (normal = 0.450). Chemical Chemical and thermal instability test and search for inclusion bodies gave positive results. Hemoglobin electrophoresis at pH 8.9 revealed absence of Hb A, a major component of fast mobility (94%), and increased Hb F and Hb A2 levels (1.5% and 4.6%, respectively). The fast fraction, isolated and purified by means of cellulose acetate electrophoresis, precipitated in acid acetone and treated with urea 8 M and mercaptoethanol, revealed an anomalous beta chain. Trypsin-digested globin peptides were separated by high-voltage electrophoresis at pH 6.4 and ascendant chromatography. With differential staining, an extra peptide was detected in an unusual site, more anodic than alpha Tp4 but in lower position. Peptide map of the fast beta chain, stained with ninhydrin, and also for Tyr, confirmed the position of the new peptide and the absence of the usual beta Tp13. The new peptide, separated by high-voltage electrophoresis at pH 3.5, revealed absence of Val and the presence of an additional Glu residue, which should appear only in position beta 126. The diagnosis of Hb Hofu (alpha 2 beta 2 126 Val----Glu; H4) was reached, thus interpreting its increase and the absence of Hb A, as an association with beta o-thalassemia, producing a mild hemolytic anemia. Evidence was obtained that Hb Hofu is a mild unstable hemoglobin variant.

Adult↗

PubMed2000

Lack of association between T-786-->C mutation in the 5'-flanking region of the endothelial nitric oxide synthase gene and essential hypertension.

Accumulating evidence strongly suggests that an alteration in nitric oxide metabolism is involved in the pathogenesis of hypertension. We recently found 2 polymorphisms in the endothelial nitric oxide synthase (eNOS) gene, a Glu298Asp missense variant in exon 7 and a T-786-->C variant in the 5'-flanking region, which are not linked to each other. In our previous reports, we showed a positive association between the Glu298Asp variant and essential hypertension, myocardial infarction, and coronary spastic angina. We also revealed that the T-786-->C variant is strongly associated with coronary spastic angina and leads to the reduction of the eNOS gene promoter activity. To further investigate the genetic involvement of the eNOS gene in essential hypertension, we examined the frequency of T-786-->C variant in two independent populations of persons with essential hypertension in Kyoto (n=215) and Kumamoto (n=186) and compared the frequency with that in each age- and gender-matched control (233 controls in Kyoto and 223 controls in Kumamoto). In both groups, the frequency of T-786-->C variant was similar in patients with hypertension and normal controls. In conclusion, the T-786-->C variant was not positively associated with essential hypertension. Given the evidence of positive association of another polymorphism in the eNOS gene, the Glu298Asp polymorphism, with essential hypertension, special attention will be required to interpret the results of a case-control study for genetic risk factors.

Adult↗

PubMed1999

Cystic fibrosis: molecular diagnosis, population screening, and public policy.

OBJECTIVE: To review the current status of scientific knowledge and opinion regarding molecular genetic testing of mutations in the CFTR gene for purposes of diagnosis and population carrier screening of cystic fibrosis (CF). DATA SOURCES: Published research findings on the nature of the CFTR gene, pilot population screening studies in the United States and Europe, and ongoing deliberations of professional and governmental agencies considering implementation of widespread testing. STUDY SELECTION: Findings relevant to the molecular heterogeneity of CFTR mutations and its implications for population carrier screening were considered. DATA EXTRACTION: Information was extracted from studies published by us and others, as made available to recent consensus panels and professional committees. DATA SYNTHESIS: These data were reevaluated in light of recent movements in professional and public policy regarding acceptability and desirability of widespread CF mutation testing. Effects to date of such testing on patient outcomes is reported. CONCLUSIONS: The ability to test for CFTR mutations at the molecular level has already improved the diagnosis of symptomatic patients and expanded the reproductive options of family members of CF patients. The same technology also holds promise of identifying asymptomatic carriers and at-risk couples without family history in the general population so that they too might be offered prenatal diagnosis or other options. However, a number of key questions remain to be worked out before a widespread national screening program can be put into practice. These include the target population to be offered testing (the entire population vs high-risk ethnic groups), the size and nature of the mutation test panel (universal vs ethnic specific), the inclusion or exclusion of CFTR variants that do not cause classical CF, the optimal testing technology, appropriate standards for laboratory quality assurance, and the development of sufficient educational materials and genetic counseling resources for test delivery, reporting, and interpretation. The answers to these questions will be relevant not only to CF testing but also to many other large-scale molecular genetic screening programs being considered in the future.

Cloning, Molecular↗

PubMed2000

A tetranucleotide repeat polymorphism in CYP19 and breast cancer risk.

The CYP19 gene codes for aromatase, a key steroidogenic enzyme involved in the conversion of androgens to estrogens. A tetranucleotide (TTTA) repeat polymorphism is present in intron 4 of CYP19; 2 out of 4 breast cancer case-control studies have reported a greater frequency of 2 specific alleles among affected women. We evaluated associations between CYP19 repeat alleles and breast cancer risk in a case-control study nested within the Nurses' Health Study cohort (incident cases: n=462; controls: n=618). We observed seven different CYP19 alleles (TTTA(7-13)). Compared to controls, cases had a statistically significant greater frequency of the 10 (TTTA)(10) repeat allele (10 allele: 2.3% vs. 0.7%, p = 0.005) and a nonsignificant increase in the frequency of the 12 (TTTA)(12) allele (12 allele: 3.1% vs. 2.1%, p = 0.11). A higher frequency of the 10 allele was observed in more advanced cancer cases defined as four or more involved nodes or distant metastasis [4+ nodes: 5/36 (13.9%) vs. 0-3 nodes: 13/330 (3.9%), p = 0.02]. Among controls, we found women with the 7 repeat allele to have decreased levels of estrone sulfate (-16.4%, p = 0.02), estrone (-6.1%, p = 0.22) and estradiol (-9.9%, p = 0.10), and a lower estrone/androstenedione ratio (E1/A) (-10.5%, p = 0.08) compared to non-carriers. A higher E1/A ratio and elevated estrogen levels were observed among carriers of the 8 repeat allele; E1/A ratio (+21.0%, p = 0.003), estrone (+7.5%, p = 0.16) and estradiol (+10.8%, p = 0.08). However, we observed no evidence of an association between these alleles and breast cancer risk. We were unable to make inferences regarding the effect of the 10 allele on hormone levels due to the small number of allele carriers in the subgroup with hormone levels. As this repeat polymorphism is not close to the splice sites in intron 4, linkage disequilibrium with other functional polymorphisms in CYP19 may explain the findings of an increased association between breast cancer and the 10 allele variant of CYP19. We did not detect any sequence variants in the regulatory region or in the adipose-specific exon I.4. The lack of an established effect on CYP19 function associated with the 10 allele means that these findings should be interpreted with caution.

Alleles↗

PubMed2000

Results of Holter monitoring U.S. Air Force aircrew with ectopy on 12-lead electrocardiograms.

PURPOSE: To evaluate the results of 24-h Holter monitoring performed on healthy U.S. Air Force aircrew with asymptomatic ectopy on resting electrocardiograms (ECG). METHODS: A historical review of the USAF Central ECG Library database was conducted on all Holter studies completed for evaluation of ECG ectopy between 1 Jan 86 and 31 Dec 97. Univariate and multivariate statistical analyses were performed to determine the association between ectopy and the aeromedical dispositions of aircrew evaluated for incidental ECG ectopy. RESULTS: During this period, 147,571 resting ECGs were submitted to the Aeromedical Consultation Service (ACS) for interpretation. The mean age of the subjects was 35 yr (range 19 to 57 yr). There were 480 24-h Holter studies performed for ECG ectopy. Of these, 49% had normal or normal variant findings; another 11% were found acceptable for flying after normal treadmill testing and echocardiography. ACS evaluation was required for the remaining 40% of subjects. Overall, 4% were permanently disqualified, and 17% were lost to follow-up. Excluding subjects lost to follow-up, 95% of aircrew were returned to flying status (with or without a waiver). CONCLUSIONS: When controlled for age, no significant difference of aeromedical outcome was seen when comparing supraventricular and ventricular ectopy. Of the subjects, 51% had abnormal Holter studies, but the vast majority were returned to flying. Results of this study provide information useful in further defining aircrew medical evaluation protocols for evaluation of asymptomatic ECG ectopy with Holter monitoring.

Adult↗

PubMed2005

Prevalence and spectrum of von Willebrand disease from western India.

BACKGROUND AND OBJECTIVE: von Willebrand disease (VWD) is one of the most common inherited bleeding disorders in the west. Limited studies from India showed a prevalence of approximately 10 per cent of VWD among the cases with hereditary bleeding disorders. VWD remains an underdiagnosed entity in India. The prevalence of different subtypes of VWD is also not known which is essential for a proper management of these cases. The present study was thus undertaken to know the prevalence of VWD and its various subtypes in the western part of our country. METHODS: A total of 796 consecutive patients presented with various bleeding manifestations were analysed. The initial screening and confirmation tests for the diagnosis of VWD included bleeding time (BT), screening coagulation tests i.e., prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), factor VIII: C assay, ristocetin-induced platelet aggregation (RIPA) and VWF antigen (VWF:Ag) estimations. VWF multimer analysis, ristocetin cofactor activity (RCOF), VWF collagen binding assay (VWF: CBA), factor VIII : VWF binding assay were also done to classify and subtype these cases. RESULTS: The patients were subtyped as per the International Society of Thrombosis and Haemostasis (ISTH) criteria. Of the 796 patients screened, 58 were diagnosed as VWD. Of the 15 families with a positive family history of bleeding, 26 additional cases were diagnosed as VWD. Majority of the patients were type 3 (59.5%) with severe clinical manifestations, about 18 per cent of type 1 VWD patients were detected in this group while the prevalence of the qualitative variants of VWD i.e., type 2 VWD was found to be 19 per cent and the prevalence of various subtypes were type 2A (9.52%), type 2B (4.76%), type 2M (1.2%), type 2N (3.6%). INTERPRETATION AND CONCLUSION: The high prevalence of type 3 and a low prevalence of type 1 VWD which is in contrast to the western reports, suggests the low awareness of the disease as also the underdiagnosis of the mild cases in our country.

Adult↗

PubMed2006

Cerebral angiography and venography for evaluation of cerebral venous thrombosis.

Cerebral venous thrombosis is an uncommon, but important cause of stroke due to its high morbidity. Though conventional catheter based angiography is becoming replaced by newer, noninvasive imaging modalities, it still plays an important role in the evaluation of patients with suspected sinus or venous thrombosis. Techniques of angiography, normal anatomy and variants, and pathological drainage patterns are discussed in reference to thrombosis of the major dural and cortical venous structures. Knowledge of the normal drainage patterns of the cerebral venous system is essential in interpreting angiographic information obtained in the evaluation of patients with suspected cerebral venous thrombosis.

Cerebral Angiography↗

PubMed1991

Synaptonemal complex karyotyping in an oligospermic patient with heterochromatin duplication in chromosome n. 9.

Synaptonemal complex karyotyping has been performed in an oligospermia of unknown etiology in a patient carrying a 9qh+ chromosomal polymorphism. The testicular histology showed hypospermatogenesis at the spermatid level and an abnormal pattern of chromatin condensation. Spermatocytes at early pachytene showed a large, asymmetric loop in SC #9, which disappeared at late pachytene, probably because of synaptic adjustment. The loop was formed by a lateral element 7.02% longer than the average normal one. The loop exceeded the centromere towards the short arm, and it is interpreted as a tandem duplication of about 50% of the paracentromeric heterochromatin. The present observation and the previously reported asynaptic loops in carriers of pericentric inversions and showing severe oligospermia suggest that chromosomal variants producing asynaptic loops may be associated with germ cell loss. Further meiotic studies in infertile carriers of such variants are indicated.

Adult↗