Fine needle aspiration cytology of mammary pseudoangiomatous stromal hyperplasia. A case report

BACKGROUND

Pseudoangiomatous stromal hyperplasia (PASH) is an unusual benign breast lesion that may occasionally present as a palpable mass.

CASE

This report describes the fine needle aspiration cytology (FNAC) features of a case of mammary PASH that presented as a palpable mass. This is the second description of the FNAC features of this lesion and the first reported case in which a diagnosis of phyllodes tumor was considered. The aspirate was cellular and contained cohesive groups of cells in which there was a dual population of epithelial and myoepithelial cells. Occasional cellular stromal fragments were present, as were typical, bipolar, bare nuclei. Admixed with the bare nuclei were large numbers of plump, spindle-shaped cells, some with intact cytoplasm. Histologic examination of the excised mass showed features typical of PASH.

CONCLUSION

Mammary PASH may present as a palpable mass and is likely to be encountered in FNAC specimens. This diagnosis should be considered when one is confronted with an aspirate containing cohesive epithelial groups, cellular stromal fragments and large numbers of single, spindle-shaped cells. These features on FNAC may result in consideration of a phyllodes tumor. The single, spindle-shaped cells may be a characteristic cytologic feature of PASH.

Parent beliefs about infant teething: a survey of Australian parents

OBJECTIVE

Parents ascribe many infant symptoms to teething, despite little evidence to support such an attribution. We report current parental beliefs about teething and its management in a suburban Australian setting.

METHODOLOGY

A written questionnaire was given to all English-speaking parents consecutively attending infant hearing testing sessions in one Melbourne municipality between August and October 1997. Approximately 90% of Victorian infants attend these sessions.

RESULTS

Parents of 92 infants (mean age 9.9 months) completed questionnaires (97% response rate). Only one believed that teething causes no problems. Most (70-85%) believed that teething causes fever, pain, irritability, sleep disturbance, mouthing/biting, drooling and red cheeks; 35-55% reported nappy rash, 'sooking', ear pulling, feeding problems, runny nose, loose stools, and infections; and a few (< 15%) reported smelly urine, constipation, colic or convulsions. Symptoms reported for a parent's own infant correlated almost perfectly with symptoms believed to be experienced by infants generally (r = 0.97, P < 0.001). Amount of infant distress when teething correlated with more 'difficult' infant temperament (r = 0.25, P < 0.05), and longer duration of symptoms per tooth correlated with parent distress (r = 0.26, P < 0. 05). Paracetamol (60%) and topical analgesia (55%) were commonly used remedies. Parents diagnose teething more by the presence of 'teething symptoms' (65%) than by palpable (43%) or visible (36%) tooth eruption.

CONCLUSION

Teething is a distressing but ill-defined phenomenon reported by almost all parents of young children, and most use some form of medication to manage it. Most symptoms are minor and relate to discomfort rather than physical illness, but a substantial minority still ascribes potentially serious symptoms to teething.

Intrapartum and neonatal single-dose nevirapine compared with zidovudine for prevention of mother-to-child transmission of HIV-1 in Kampala, Uganda: HIVNET 012 randomised trial

BACKGROUND

The AIDS Clinical Trials Group protocol 076 zidovudine prophylaxis regimen for HIV-1-infected pregnant women and their babies has been associated with a significant decrease in vertical HIV-1 transmission in non-breastfeeding women in developed countries. We compared the safety and efficacy of short-course nevirapine or zidovudine during labour and the first week of life.

METHODS

From November, 1997, to April, 1999, we enrolled 626 HIV-1-infected pregnant women at Mulago Hospital in Kampala, Uganda. We randomly assigned mothers nevirapine 200 mg orally at onset of labour and 2 mg/kg to babies within 72 h of birth, or zidovudine 600 mg orally to the mother at onset of labour and 300 mg every 3 h until delivery, and 4 mg/kg orally twice daily to babies for 7 days after birth. We tested babies for HIV-1 infection at birth, 6-8 weeks, and 14-16 weeks by HIV-1 RNA PCR. We assessed HIV-1 transmission and HIV-1-free survival with Kaplan-Meier analysis.

FINDINGS

Nearly all babies (98.8%) were breastfed, and 95.6% were still breastfeeding at age 14-16 weeks. The estimated risks of HIV-1 transmission in the zidovudine and nevirapine groups were: 10.4% and 8.2% at birth (p=0.354); 21.3% and 11.9% by age 6-8 weeks (p=0.0027); and 25.1% and 13.1% by age 14-16 weeks (p=0.0006). The efficacy of nevirapine compared with zidovudine was 47% (95% CI 20-64) up to age 14-16 weeks. The two regimens were well tolerated and adverse events were similar in the two groups.

INTERPRETATION

Nevirapine lowered the risk of HIV-1 transmission during the first 14-16 weeks of life by nearly 50% in a breastfeeding population. This simple and inexpensive regimen could decrease mother-to-child HIV-1 transmission in less-developed countries.

In vivo binding and antitumor activity of Ch14.18

The melanoma reactive chimeric 14.18 (ch14.18) antibody can mediate enhanced in vitro lysis of human M-21 melanoma cells. This study analyzes the antitumor effects and the in vivo binding of ch14.18 antibody with M-21 melanoma cells in severe combined immunodeficiency (SCID) mice. Outgrowth of tumors was prevented in 6/6 animals by the simultaneous subcutaneous injection of peripheral blood mononuclear cells (PBMC) [3 x 10(6) cells (2 animals); 10 x 10(6) cells (2 animals); and 30 x 10(6) cells (2 animals)], with 0.5 mg ch14.18, 1,500 U interleukin 2 (IL-2), and 10(6) M-21 cells. In contrast, 7 of 7 control mice that received M-21 cells alone, 7 of 7 mice that received M-21 cells and ch14.18, and 5 of 6 mice that received M-21 cells plus PBMC plus IL-2, grew subcutaneous tumors. The in vivo localization of ch14.18 was then evaluated in an intraperitoneal (i.p.) tumor model, where 0.3 cm melanoma nodules develop within 3 weeks after the i.p. administration of M-21 cells. Flow cytometric and immunohistochemical analysis revealed the GD2 antigen present throughout the tumor nodule. Intraperitoneal administration of 0.01, 0.1, or 1.0 mg of ch14.18 to SCID mice previously engrafted i.p. with M-21 cells resulted in detectable ch14.18 binding to tumor cells in vivo within 10 hours of antibody administration. Ch14.18 penetration was limited to approximately 20 cell layers, demonstrating that ch14.18 has limited access to some cells in large tumor nodules. This study demonstrates that the addition of ch14.18 to IL-2 and human effector cells can result in significant antitumor activity by preventing the establishment of tumor nodules. These results suggest that clinical testing of IL-2 plus ch14.18 might be most effective if used in the setting of microscopic residual disease. Therapies that enhance ch14.18 penetration into tumor nodules should be evaluated with ch14.18 for patients with advanced melanoma.

Treatment of iatrogenic previable premature rupture of membranes with intra-amniotic injection of platelets and cryoprecipitate (amniopatch): preliminary experience

OBJECTIVE

Our aim was to describe the treatment of iatrogenic previable premature rupture of membranes with the intra-amniotic injection of platelets and cryoprecipitate (amniopatch).

STUDY DESIGN

Patients with iatrogenic previable premature rupture of membranes and without evidence of intra-amniotic infection underwent transabdominal intra-amniotic injection of platelets and cryoprecipitate through a 22-gauge needle. The study was approved by the Institutional Review Board of St Joseph's Hospital in Tampa, Florida, and all patients gave written informed consent.

RESULTS

Seven patients with iatrogenic preterm premature rupture of membranes underwent placement of an amniopatch. Membrane sealing was verifiable in 6 of 7 patients. Three patients had iatrogenic preterm premature rupture of membranes after operative fetoscopy, 3 cases were after genetic amniocentesis, and 1 was after diagnostic fetoscopy. Three pregnancies progressed well, with restoration of the amniotic fluid volume and no further leakage. Two patients had unexplained fetal death despite successful sealing. One case of bladder outlet obstruction had no further leakage, but oligohydramnios persisted and did not allow unequivocal documentation of sealing. One patient miscarried from twin-twin transfusion, but the amniotic cavity was sealed.

CONCLUSIONS

Iatrogenic preterm premature rupture of membranes can be treated effectively with an amniopatch. The technique is simple and does not require knowledge of the exact location of the defect. Unexpected fetal death from the procedure may be attributable to vasoactive effects of platelets or indigo carmine. Although the appropriate dose of platelets and cryoprecipitate needs to be established, the amniopatch may mean that iatrogenic preterm premature rupture of membranes no longer needs to be considered a devastating complication of pregnancy.

Post-positivistic critical multiplism: a beginning dialogue

Following the recognition that logical positivism was no longer tenable in modern science, post-positivism and its research methodology, critical multiplism, emerged and offered a new way of thinking about science. Though not a panacea, critical multiplism, in which methodological pluralism is advocated, offers a way around the debate of which conception of science is appropriate for nursing and, as such, poses advantages for nursing scientific knowledge development.

In vitro laser welding of amniotic membranes

OBJECTIVE

To test in vitro the feasibility of welding amniotic membranes using Nd:YAG laser energy.

STUDY DESIGN

Fresh fetal membranes from term pregnancies were washed and cut into 1 cm2 pieces. Pooled cryoprecipitate (CPT), 50% albumin (Alb), or polytetrafluoroethilene (e-PTFE) were used as solder medium. The optimal settings of the laser were determined. Results were assessed quantitatively and semi-quantitatively using Pearson Chi-square analysis.

RESULTS

Laser welding of amniotic membranes was successful in 82.6% of experiments with e-PTFE and in 10.7% of experiments with CPT (P < 0.001). The strength of the welding was also significantly better with e-PTFE (P < 0.001). Optimal results were obtained using 1-7 Watts and 0.1-1 seconds. Laser welding was unsuccessful in 100% of experiments with Alb.

CONCLUSIONS

Laser welding of fetal membranes can be accomplished with e-PTFE and to a lesser degree with the CPT using Nd:YAG energy under low wattage-high exposure settings. Further studies are underway to test other grafting or soldering materials.

Tapping-mode atomic force microscopy produces faithful high-resolution images of protein surfaces

Compared to contact-mode atomic force microscopy (CMAFM), tapping-mode atomic force microscopy (TMAFM) has the advantage of allowing imaging surfaces of macromolecules, even when they are only weakly attached to the support. In this study, TMAFM is applied to two different regular protein layers whose structures are known to great detail, the purple membrane from Halobacterium salinarum and the hexagonally packed intermediate (HPI) layer from Deinococcus radiodurans, to assess the faithfulness of high-resolution TMAFM images. Topographs exhibited a lateral resolution between 1.1 and 1. 5 nm and a vertical resolution of approximately 0.1 nm. For all protein surfaces, TMAFM and CMAFM topographs were in excellent agreement. TMAFM was capable of imaging the fragile polypeptide loop connecting the transmembrane alpha-helices E and F of bacteriorhodopsin in its native extended conformation. The standard deviation (SD) of averages calculated from TMAFM topographs exhibited an enhanced minimum (between 0.1 and 0.9 nm) that can be assigned to the higher noise of the raw data. However, the SD difference, indicating the flexibility of protein subunits, exhibited an excellent agreement between the two imaging modes. This demonstrates that the recently invented imaging-mode TMAFM has the ability to faithfully record high-resolution images and has sufficient sensitivity to contour individual peptide loops without detectable deformations.

The academic global virtual concept in clinical cancer research and its application to breast cancer: The Breast Cancer International Research Group

In contrast to previous decades, the 1990s have witnessed an increase of new agents with significant activity in breast cancer, including chemotherapy, hormone therapy, and, more recently, biologic modifiers. All information appears to confirm that such a trend will persist and even accelerate in the coming decades. Unless clear strategies of development for new drugs are strictly followed, it will become difficult to adequately assess the many new agents with potentially important activity against breast cancer, and patient access may become a limiting key factor. The academic, global virtual concept is calling for the definition of a new relationship between the pharmaceutical industry and clinical researchers. The main aspect is related to the creation of partnerships with an academically controlled global strategy of development for promising new agents, in which the quality and independence of processes (adjuvant setting, for example) are critical. The means are based on the globalization of patient access (worldwide network) and the virtuality of the approach (modern means of communication as well as access to subgroups of patients). The Breast Cancer International Research Group is the first academic global virtual cooperative group in breast cancer and is making contributions in the development of new drugs, such as taxanes, new antiestrogens, and new cytokines.

Increased T-cell receptor vbeta2 chain expression in skin homing lymphocytes in psoriasis

Studies have shown over-representation of certain T-cell receptor (TCR) Vbeta chains in lesional psoriatic skin, implying selection or expansion, possibly by bacterial superantigen. We investigated the pattern of TCR Vbeta chain usage in peripheral blood lymphocytes (PBL) bearing the skin homing receptor cutaneous lymphocyte associated antigen (CLA) in psoriasis patients. Results showed increased expression of TCR Vbeta2 in CLA-positive PBL in psoriasis patients (n = 15) compared with normals (n = 10); P < 0.002. As Vbeta2 is preferentially expressed by lymphocytes responding to certain bacterial superantigens, this study could possibly indicate a role for superantigens in the pathogenesis of psoriasis.

Sequence analysis of the diabetes-protective human leukocyte antigen-DQB1*0602 allele in unaffected, islet cell antibody-positive first degree relatives and in rare patients with type 1 diabetes

The human leukocyte antigen (HLA)-DQA1*0102/DQB1*0602/DRB1*1501 (DR2) haplotype confers strong protection from type 1 diabetes. Growing evidence suggests that such protection may be mostly encoded by the DQB1*0602 allele, and we reported that even first degree relatives with islet cell antibodies (ICA) have an extremely low diabetes risk if they carry DQB1*0602. Recently, novel variants of the DQB1*0602 and *0603 alleles were reported in four patients with type 1 diabetes originally typed as DQB1*0602 with conventional techniques. One inference from this observation is that DQB1*0602 may confer absolute protection and may never occur in type 1 diabetes. By this hypothesis, all patients typed as DQB1*0602 positive with conventional techniques should carry one of the above diabetes-permissive variants instead of the protective DQB1*0602. Such variants could also occur in ICA/DQB1*0602-positive relatives, with the implication that their diabetes risk could be significantly higher than previously estimated. We therefore sequenced the DQB1*0602 and DQA1*0102 alleles in all ICA/DQB1*0602-positive relatives (n = 8) previously described and in six rare patients with type 1 diabetes and DQB1*0602. We found that all relatives and patients carry the known DQB1*0602 and DQA1*0102 sequences, and none of them has the mtDNA A3243G mutation associated with late-onset diabetes in ICA-positive individuals. These findings suggest that diabetes-permissive DQB1*0602/3 variants may be very rare. Thus, although the protective effect associated with DQB1*0602 is extremely powerful, it is not absolute. Nonetheless, the development of diabetes in individuals with DQB1*0602 remains extremely unlikely, even in the presence of ICA, as confirmed by our further evaluation of ICA/DQB1*0602-positive relatives, none of whom has yet developed diabetes.

A phase I/II study of the safety and pharmacokinetics of nevirapine in HIV-1-infected pregnant Ugandan women and their neonates (HIVNET 006)

OBJECTIVE

To determine the safety, pharmacokinetics, tolerance, antiretroviral activity, and infant HIV infection status after giving a single dose of nevirapine to HIV-1-infected pregnant women during labor and their newborns during the first week of life.

DESIGN

An open label phase I/II study.

SETTING

Tertiary care hospital, Kampala, Uganda.

PATIENTS AND INTERVENTIONS

Nevirapine, 200 mg, was given as a single dose during labor to 21 HIV-1-infected pregnant Ugandan women. In cohort 1, eight infants did not receive nevirapine whereas in cohort 2, 13 infants received a single dose of nevirapine, 2 mg/kg, at 72 h of age.

OUTCOMES

The number and type of adverse events; nevirapine concentrations in the plasma and breast milk; maternal plasma HIV-1 RNA copy number before and up to 6 weeks after delivery; and HIV-1 infection status of the infants were monitored.

RESULTS

Nevirapine was well tolerated by women and infants; no serious adverse events that were related to nevirapine were observed. Median nevirapine concentration in the women at delivery was 1623 ng/ml (range 238-2356 ng/ml); median cord/maternal blood ratio of 0.75 (0.37-0.93). The median half-life in women was 61.3 h (27-90 h) and the transplacental nevirapine half-life in infants who did not receive a neonatal dose was 54 h. The median half-life after a single dose at 72 h in infants was 46.5 h. During the first week of life, the median colostrum/breast milk to maternal plasma nevirapine concentration was 60.5% (25-122%). The median nevirapine concentration in breast milk 1 week after delivery was 103 ng/ml (25-309 ng/ml). Plasma nevirapine concentrations were above 100 ng/ml in all infants from both cohorts tested at age 7 days. Maternal HIV-1 RNA levels decreased by a median of 1.3 logs at 1 week postpartum, and returned to baseline by 6 weeks postpartum. Detectable plasma HIV-1 RNA was observed in one out of 22 (4.5%) infants at birth; three out of 21 (14%) at 6 weeks; and four out of 21 (19%) at 6 months of age.

CONCLUSION

The administration of a single dose of nevirapine to women during labor and to their newborns at 72 h was well tolerated and showed potent antiretroviral activity in the women at 1 week after dosing without rebound above baseline 6 weeks after a single dose. The nevirapine concentration was maintained above the target of 100 ng/ml in infants at age 7 days, even in those infants not receiving a neonatal dose. This regimen has promise as prophylaxis against intrapartum and early breast milk transmission in a breastfeeding population.

High resolution genetic typing of the class II HLA-DRB1 locus using group-specific amplification and SSO-hybridisation in microplates

The HLA-DRB1 locus is one of the most polymorphic HLA class II loci and rapid and accurate typing of this polymorphism is important both in bone-marrow transplantation, analysis of disease association and in forensic medicine. The allelic variation at DRB1 is characterized by combinations of a limited number of amino-acid motifs, reducing the resolution of a typing strategy based on a single PCR and subsequent analysis of polymorphic motifs. In the present paper we describe a strategy for typing of DRB1 based on eight allele-specific PCRs followed by sandwich hybridization to immobilized probes in a microplate format. The combined approach results in a rapid typing system with very high resolution. Using a rapid DNA extraction protocol, a complete HLA-DRB1 typing can be performed in less than a day.

Chronic compartment syndrome affecting the lower limb: MIBI perfusion imaging as an alternative to pressure monitoring: two case reports

Intracompartmental pressure monitoring remains the primary method of diagnosing chronic compartment syndrome. MIBI perfusion imaging is widely available and offers a radionuclear imaging technique for diagnosing this condition. Although the results are not identical with those from pressure monitoring, MIBI may offer a useful screening test for this condition.

An encyclopedia of mouse genes

The laboratory mouse is the premier model system for studies of mammalian development due to the powerful classical genetic analysis possible (see also the Jackson Laboratory web site, http://www.jax.org/) and the ever-expanding collection of molecular tools. To enhance the utility of the mouse system, we initiated a program to generate a large database of expressed sequence tags (ESTs) that can provide rapid access to genes. Of particular significance was the possibility that cDNA libraries could be prepared from very early stages of development, a situation unrealized in human EST projects. We report here the development of a comprehensive database of ESTs for the mouse. The project, initiated in March 1996, has focused on 5' end sequences from directionally cloned, oligo-dT primed cDNA libraries. As of 23 October 1998, 352,040 sequences had been generated, annotated and deposited in dbEST, where they comprised 93% of the total ESTs available for mouse. EST data are versatile and have been applied to gene identification, comparative sequence analysis, comparative gene mapping and candidate disease gene identification, genome sequence annotation, microarray development and the development of gene-based map resources.

A clinical trial of a chest-pain observation unit for patients with unstable angina. Chest Pain Evaluation in the Emergency Room (CHEER) Investigators

BACKGROUND

Nearly half of patients hospitalized with unstable angina eventually receive a non-cardiac-related diagnosis, yet 5 percent of patients with myocardial infarction are inappropriately discharged from the emergency department. We evaluated the safety, efficacy, and cost of admission to a chest-pain observation unit (CPU) located in the emergency department for such patients.

METHODS

We performed a community-based, prospective, randomized trial of the safety, efficacy, and cost of admission to a CPU as compared with those of regular hospital admission for patients with unstable angina who were considered to be at intermediate risk for cardiovascular events in the short term. A total of 424 eligible patients were randomly assigned to routine hospital admission (a monitored bed under the care of the cardiology service) or admission to the CPU (where patients were cared for according to a strict protocol including aspirin, heparin, continuous ST-segment monitoring, determination of creatine kinase isoenzyme levels, six hours of observation, and a study of cardiac function). The CPU was managed by the emergency department staff. Patients whose test results were negative were discharged, and the others were hospitalized. Primary outcomes (nonfatal myocardial infarction, death, acute congestive heart failure, stroke, or out-of-hospital cardiac arrest) and use of resources were compared between the two groups.

RESULTS

The 212 patients in the hospital-admission group had 15 primary events (13 myocardial infarctions and 2 cases of congestive heart failure), and the 212 patients in the CPU group had 7 events (5 myocardial infarctions, 1 death from cardiovascular causes, and 1 case of congestive heart failure). There was no significant difference in the rate of cardiac events between the two groups (odds ratio for the CPU group as compared with the hospital-admission group, 0.50; 95 percent confidence interval, 0.20 to 1.24). No primary events occurred among the 97 patients who were assigned to the CPU and discharged. Resource use during the first six months was greater among patients assigned to hospital admission than among those assigned to the CPU (P<0.01 by the rank-sum test).

CONCLUSIONS

A CPU located in the emergency department can be a safe, effective, and cost-saving means of ensuring that patients with unstable angina who are considered to be at intermediate risk of cardiovascular events receive appropriate care.

Resistance mutations in protease and reverse transcriptase genes of human immunodeficiency virus type 1 isolates from patients with combination antiretroviral therapy failure

High-density oligonucleotide arrays were used to determine the sequence of the protease (PR) and reverse transcriptase (RT) genes of human immunodeficiency virus type 1 isolates from 35 patients in whom combination therapy that included a protease inhibitor had failed. Isolates had a median of three PR mutations (range, none to six). Three isolates had no known resistance mutations in PR. Twelve isolates (34%) had two or fewer resistance mutations in PR. The most commonly observed PR mutations were L10I, V82A/T/F, and L90M. No mutations were observed at codons 30 or 48. Mutations at RT codons 215 and 184 were observed in the majority of isolates. These data suggest that therapy can fail in some patients with relatively few PR resistance mutations. Clinical failure in the absence of resistance mutations implies inadequate drug exposure due to pharmacologic factors or suboptimal patient adherence to drug therapy.

The importance of stabilization as an endpoint in the treatment of metastatic colorectal carcinoma: recent quality of life studies

Assessment of the effectiveness of new anticancer chemotherapies in clinical trials is usually based on the degree of objective response obtained. Response is usually defined as 'complete', when there is complete disappearance of all detectable tumor, or 'partial', when there is a 50% reduction in the sum of the products of the largest perpendicular diameters of all measurable disease, with no new lesions (Advanced Colorectal Cancer Meta-analysis Project). Both clinicians, concerned with the welfare of their patients, and healthcare administrators, keen to be assured of cost-effectiveness within their restricted budgets, see such response (along with enhanced survival) as a cardinal indicator of efficacy. Response rates are a primary influence on their decision to treat, or to sanction payment for treatment, with a particular medication. There is, however, growing evidence to suggest that stabilization of disease is also an important endpoint in chemotherapy for carcinoma, with important benefits for the patients' quality of life (QoL). We report on recent international studies on the effects of the topoisomerase I inhibitor irinotecan (Campto) as second-line treatment in patients with metastatic colorectal cancer. These confirm the value of stabilization, as well as response, in such patients, not only in bringing QoL benefits, but also in reducing length of hospitalization and hence costs.

Restricted tissue expression pattern of a novel human rasGAP-related gene and its murine ortholog

The mammalian rasGAPs constitute a group of widely expressed proteins involved in the negative regulation of ras-mediated signaling. In this study we have isolated a novel human gene, RASAL (Ras GTPase-activating-like) and its murine ortholog, MRASAL which are most similar to the GAP1 family of rasGAP proteins, based upon the presence and organization of specific conserved domains. Full-length human and murine mRNA sequences are predicted to encode 804 and 799 amino acid polypeptides, respectively. Sequence analysis of these two proteins revealed the presence of two N-terminal calcium-dependent phospholipid binding C2 domains, a conserved GAP related domain (GRD) and a C-terminal pleckstrin homology (PH) domain. Northern blot and mRNA in situ hybridization analyses indicate that RASAL, in contrast to other mammalian rasGAP proteins, has a limited expression pattern; RASAL is highly expressed in the follicular cells of the thyroid and the adrenal medulla and expressed at lower levels in brain, spinal cord and trachea. Human RASAL has been localized by radiation hybrid mapping to chromosome 12q23-24.