Faculty Bibliography

Neocentromeres are fully functional centromeres found on rearranged or marker chromosomes that have separated from endogenous centromeres. Neocentromeres often result in partial tri- or tetrasomy because their formation confers mitotic stability to acentric chromosome fragments that would normally be lost. We describe the prenatal identification and characterization of a de novo supernumerary marker chromosome (SMC) containing a neocentromere in a 20-wk fetus by the combined use of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). GTG-banding of fetal metaphases revealed a 47,XY,+mar karyotype in 100% of cultured amniocytes; parental karyotypes were both normal. Although sequential tricolor FISH using chromosome-specific painting probes identified a chromosome 10 origin of the marker, a complete panel of chromosome-specific centromeric satellite DNA probes failed to hybridize to any portion of the marker. The presence of a neocentromere on the marker chromosome was confirmed by the absence of hybridization of an all-human-centromere alpha-satellite DNA probe, which hybridizes to all normal centromeres, and the presence of centromere protein (CENP)-C, which is associated specifically with active kinetochores. Based on CGH analysis and FISH with a chromosome 10p subtelomeric probe, the marker was found to be an inversion duplication of the distal portion of chromosome 10p. Thus, the proband's karyotype was 47,XY,+inv dup(10)(pter-->p14 approximately 15::p14 approximately 15-->neo-->pter), which is the first report of partial tetrasomy 10p resulting from an analphoid marker chromosome with a neocentromere. This study illustrates the use of several molecular strategies in distinguishing centric alphoid markers from neocentric analphoid markers.

Idiopathic thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy of obscure etiology. The fundamental pathologic lesion is a hyaline thrombus composed of platelets and some fibrin accompanied by endothelial cell proliferation and detachment, in the absence of an inflammatory response. We have previously demonstrated that plasmas from patients with both idiopathic TTP and a related disorder, sporadic hemolytic-uremic syndrome (HUS), induce apoptosis and expression of the apoptosis-associated molecule Fas (CD95) in vitro in those lineages of microvascular endothelial cells (MVECs) that are affected pathologically. We now demonstrate the presence of enhanced MVEC apoptosis in splenic tissues from patients with TTP, documented by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) and morphology. This is accompanied by elevated Fas expression. It contrasts with the absence of apoptosis in splenic tissues obtained after splenectomy for trauma or immune thrombocytopenic purpura. TUNEL-positive cells, identified by immunohistochemistry as MVECs or macrophages, presumably engulfing apoptotic ECs, are noted in numerous areas, including those apart from microthrombi. Thus, it is unlikely that EC apoptosis is simply a sequela of thrombus formation. Based on these data, we propose that MVEC apoptosis is of pathophysiologic significance in idiopathic TTP/sporadic HUS.

Human sacral appendages have rarely been reported. We present a neonate with a thoracolumbar appendage resembling a penis, and discuss the nature of the anomaly and its diagnosis and management.

OBJECTIVES: Systemic lupus erythematosus and antiphospholipid antibody, often identified in patients with systemic lupus erythematosus, are associated with poor pregnancy outcome. This study distinguishes between the effect of each of these factors on gestational outcome and placental pathologic conditions in pregnant patients with systemic lupus erythematosus. STUDY DESIGN: Thirty-seven pregnancies and 40 placentas from 33 women with systemic lupus erythematosus were studied prospectively. RESULTS: Systemic lupus erythematosus alone, but not systemic lupus erythematosus activity, was associated with increased spontaneous abortions, preterm gestations, and fetal growth restriction. Placental correlates were ischemic-hypoxic change, decidual vasculopathy, decidual and fetal thrombi, chronic villitis, and decreased placental weight. Extensive infarction and fetal death were important antiphospholipid antibody-related findings. CONCLUSIONS: Decidual vasculopathy/coagulopathy appears to mediate the antiphospholipid antibody-related and much of the systemic lupus erythematosus-related deleterious effect on the placenta and gestational outcome. The presence of antiphospholipid antibody largely, but not invariably, predicts fetal death. Antiphospholipid antibody-independent chronic villitis may represent a second mechanism of systemic lupus erythematosus-related change.

The mean mature spermatid count (MMSC) provides a useful, simplified quantitative evaluation of human spermatogenesis that is based on the number of mature spermatids in histological sections of testicular biopsies. Here, the activity of the acid-fast (AF) stain was compared to that of the usual hematoxylin and eosin (H&E) stain in performing the MMSC. Thirty bilateral testicular biopsies showing normal spermatogenesis were chosen retrospectively from 15 subfertile patients with obstructive azoospermia or severe oligospermia. The MMSC was determined on each biopsy by utilizing both H&E and AF stains. The AF stain proved to be specific for the mature spermatids normally counted for the MMSC. It simplified recognition of mature spermatids, thereby shortening the overall time required for the procedure. The mean AF MMSC was lower than the mean H&E MMSC, and the mean interobserver differences were decreased. The AF stain is a superior stain for the MMSC when used in conjunction with the H&E stain for descriptive histology.

We report two cases of desmoplastic small round cell tumor (DSRCT) with novel molecular variants of the specific EWS-WT1 gene fusion. This fusion usually encodes a chimeric RNA with an in-frame junction of exon 7 of EWS to exon 8 of WT1. In one variant patient, the EWS-WT1 fusion transcript contained an in-frame junction of exon 9 of EWS to exon 8 of WT1. Moreover, in this patient the tumor arose in the hand, an extremely unusual site for DSRCT. In the second patient, an in-frame junction of exon 10 of EWS to exon 8 of WT1 was present. These two cases of DSRCT show that the molecular variability in the EWS breakpoint observed in the EWS-FLI1 fusion of Ewing's sarcoma can occur in DSRCT as well. This type of heterogeneity is relevant to the interpretation of molecular diagnostic assays and could also affect the functional properties of the encoded chimeric transcription factors.