Chromosomal assignment of the gene for human DNA-PKcs interacting protein (KIP) on chromosome 15q25.3–q26.1 by somatic hybrid analysis and fluorescence in situ hybridization

We report the chromosomal location of the gene for DNA-PKcs interacting protein KIP. Based on fluorescence in situ hybridization and polymerase chain reaction (PCR)-based analyses with both a human/rodent monochromosomal hybrid cell panel and a radiation hybrid mapping panel, this gene was mapped to q25.3–q26.1 region on chromosome 15. Received: June 18, 1998 / Accepted: July 21, 1998     

Evolution of latent hypoparathyroidism in familial 22q11 deletion syndrome

Latent hypoparathyroidism (LHP), the inability to increase midmolecular parathyroid hormone levels appropriately during a hypocalcemic challenge, was reported previously in an asymptomatic woman with tetralogy of Fallot. This woman's fourth child died with DiGeorge anomaly. Seven years later, we restudied the index patient with LHP and evaluated three generations of her family for parathyroid dysfunction, cardiac abnormalities, and del 22(q11). Deletions were found in six relatives, three with conotruncal cardiac defects and three with a structurally normal heart. We found significant transgenerational noncardiac phenotypic variability, including learning difficulties, dysmorphic facial appearance, and psychiatric illness. A spectrum of parathyroid gland dysfunction associated with the del 22(q11) was seen, ranging from hypocalcemic hypoparathyroidism to normocalcemia with abnormally low basal intact parathyroid hormone (iPTH) levels. In addition, LHP found in the index patient 7 years ago had evolved to frank hypocalcemic hypoparathyroidism. In this family, which is the largest family with 22q11 deletions studied to date, parathyroid gland dysfunction evolved over time. We suggest that the calcium parathyroid hormone axis of unrelated patients with del 22(q11) be followed closely for the development of hypocalcemic hypoparathyroidism. Am. J. Med. Genet. 69:50–55, 1997. © 1997 Wiley-Liss, Inc.     

Common ancestral mutations in the MEN1 gene is likely responsible for the prolactinoma variant of MEN1 (MEN1Burin) in four kindreds from Newfoundland

Familial multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder with affected individuals developing parathyroid, gastrointestinal (GI) endocrine, and anterior pituitary tumors. Four large kindreds from the Burin peninsula/Fortune Bay area of Newfoundland with prominent features of prolactinomas, carcinoids, and parathyroid tumors (referred to as MEN1_Burin) have been described, and they show linkage to 11q13, the same locus as that of MEN1. Haplotype analysis with 16 polymorphic markers now reveals that representative affected individuals from all four families share a common haplotype over a 2.5 Mb region. A nonsense mutation in the MEN1 gene has been found to be responsible for the disease in the affected members in all four of the MEN1_Burin families, providing convincing evidence of a common founder. Hum Mutat 11:264–269, 1998. Published 1998 Wiley-Liss, Inc.     

Frequent loss of chromosome arm Ip DNA in parathyroid adenomas

Two molecular defects have been described in parathyroid adenomas: rearrangement and overexpression of the PRADI/cyclin DI oncogene and allelic loss of chromosome II DNA, often including the multiple endocrine neoplasia type I (MENI) putative tumor suppressor gene region. In an effort to identify additional parathyroid tumor suppressor genes, we examined 25 parathyroid adenomas for tumor-specific allelic loss of polymorphic DNA loci located near known or candidate tumor suppressor genes. Control leukocyte DNA from all 25 patients was heterozygous for I or more of the 9 chromosome I markers examined. Allelic loss at I or more of these informative loci on chromosome I was observed in 10 of 25 (40%) adenomas. Although many tumors lost extensive regions on chromosome I, all but one of these tumors had allelic loss of distal I p (I p32-pter); four tumors also lost loci on Iq. Allelic loss at IIqI3, the site of the MEN I gene, was detected in 5 of 2I (24%) informative cases, including 3 with Ip loss. In contrast, allelic loss was rarely observed at loci on 99 and Iop and was not observed at loci on 3p, 3q. 4p, 5q, I2q, I4q, I8q, 22q, or Xp. In summary, clonal allelic loss of loci on chromosome arm Ip is a frequent feature of parathyroid adenomas, implying that inactivation of a tumor suppressor gene(s) on Ip commonly contributes to their pathogenesis. © 1995 Wiley-Liss, Inc.     

Clonal chromosomal changes in juxta-articular myxoma

 Cytogenetic analysis of a juxta-articular myxoma revealed two distinct cytogenetically abnormal cell populations: inv(2)(p15q36) and +7, t(8;22)(q11–12; q12–13). These clonal chromosomal changes, the first to be reported in this tumour type, suggest that at least some juxta-articular myxomas are neoplastic rather than reactive in nature. Received: 8 June 1998 / Accepted: 17 August 1998     

Differential expression of the calcium sensing receptor and combined loss of chromosomes 1q and 11q in parathyroid carcinoma

Malignant transformation of parathyroid tumours is rare. Nevertheless, this small subset of malignant tumours often creates diagnostic and therapeutic problems. In this work, the morphological characteristics of 26 primary parathyroid carcinomas and seven metastases have been studied. Furthermore, immunohistochemical expression profiles for the calcium sensing receptor (CASR), cyclin D1 (CCND1), and Ki-67 were determined for parathyroid carcinomas and compared with adenomas and hyperplasias using a tissue microarray. Loss of heterozygosity (LOH) of the chromosome 1q region containing the HRPT2 gene and chromosome 11q (MEN1) was determined in the carcinomas. In contrast to the adenomas and hyperplasias, 31% of carcinomas demonstrated down-regulation of CASR. A significant correlation was found between CASR expression and the Ki-67 proliferation index. Chromosome 1q and chromosome 11q LOH were found in 12 of 22 (55%) and 11 of 22 (50%) carcinomas tested, respectively. Combined 1q and 11q LOH was seen in 8 of 22 (36%) carcinomas, in contrast to the low percentage of LOH reported in both regions in adenomas. In conclusion, this study demonstrates that combined 1q and 11q LOH in parathyroid tumours is suggestive of malignant behaviour. Strong down-regulation of the CASR protein is seen in a proportion of parathyroid carcinomas with a high proliferation index.     

Deletion mapping of endocrine tumors localizes a second tumor suppressor gene on chromosome band 11q13

Multiple endocrine neoplasia type 1 syndrome (MEN1, MIM 131100), an autosomal dominant disease, is characterized by parathyroid hyperplasia, pancreatic endocrine tumors, and pituitary adenomas. These tumors also occur sporadically. Both the familial (MEN1) and the sporadic tumors reveal loss of heterozygosity (LOH) for chromosome band 11q13 sequences. Based on prior linkage and LOH analyses, the MEN1 gene was localized between PYGM and D11S460. Recently, the MEN1 gene (menin) has been cloned from sequences 30-kb distal to PYGM. We performed deletion mapping on 25 endocrine tumors (5 MEN1 and 20 sporadic) by using 21 polymorphic markers on chromosome band 11q13. Of these, two (137C7A, 137C7B) were derived from PYGM-containing BAC (bacterial artificial chromosome-137C7) sequences, one from INT2-containing cosmid sequences and the marker D11S4748, a (CA)₂₀ repeat marker that was developed by us. The LOH analysis shows that the markers close to the MEN1 (menin) gene were not deleted in three of the tumors. These tumors, however, showed LOH for distal markers. Thus, the data suggest the existence of a second tumor suppressor gene on chromosome band 11q13. Genes Chromosomes Cancer 22:130–137, 1998. © 1998 Wiley-Liss, Inc.     

Effects of saline loading on jejunal absorption of calcium,sodium, and water,and on parathyroid hormone secretion in the rat

Summary To investigate whether intestinal calcium absorption parallels that of sodium following extracellular fluid volume expansion, the effects of saline loading on intestinal transport of calcium. sodium and water were studied in rats by perfusing jejunal loops in situ.After calcium-free saline infusion net calcium absorption was reversed similar to that of sodium and water and net secretion occurred. Concurrently, blood-to-lumen (b-l) calcium flux, measured using⁴⁵Ca, increased significantly (P<0.001). Following expansion with calcium-containing Ringer a similar reversal of net calcium, sodium and water flux was also observed. Again, the b-l calcium flux increased but to a significantly lesser extent (P<0.05). Plasma ionized calcium remained unchanged after calcium-rich Ringer loading, but decreased significantly (P<0.001) when calcium was omitted from the solution. Plasma immunoreactive parathyroid hormone was unchanged after expansion with the calcium containing solution but increased following calcium-free infusion.It is concluded that after extracellular fluid volume expansion: 1. net jejunal calcium absorption is decreased; 2. the decrease parallels that of sodium and water; 3. b-l calcium transport is enhanced to a greater degree by calcium-free Ringer infusion than by a calcium-rich solution. This difference could be the result of increased parathyroid hormone secretion.     

Parathyroid hormone reserve in 22q11.2 deletion syndrome

ObjectiveWe hypothesized that most patients with 22q11.2 deletion and a history of hypocalcemia have inadequate parathyroid function, manifested by intact parathyroid hormone levels below normal. We aimed to evaluate intact parathyroid hormone levels both during normocalcemia and at hypocalcemia, in this population.Study DesignRetrospective chart review of 103 patients with 22q11.2 deletion born since 1997 and cared for at the Children's Hospital of Philadelphia. Calcium and intact parathyroid hormone drawn simultaneously were recorded, along with clinical presentation at hypocalcemia.ResultsForty-seven simultaneous Ca/intact parathyroid hormone values were available. Seventy-nine percent of calcium levels and 81% of parathyroid hormone levels were within normal range. There were 19 patients with a history of symptomatic hypocalcemia, for whom any available simultaneous Ca/parathyroid hormone levels, before, during, or after hypocalcemia were analyzed. In this subgroup, 59% of calcium and 76% of parathyroid hormone levels were normal. None had an intact parathyroid hormone of >39.2 pg/mL at hypocalcemia. Seventy-three percent of hypocalcemic events had a precipitating stressor.ConclusionsHypoparathyroidism in 22q11.2 deletion is mild, manifesting as a phenomenon of decreased parathyroid hormone reserve. Subjects are normocalcemic most of the time, but are unable to mount elevated intact parathyroid hormone levels, and therefore unable to correct hypocalcemia, in response to stressors.     

Deletion of 11q23 and cyclin D1 overexpression are frequent aberrations in parathyroid adenomas

Hyperparathyroidism may result from parathyroid hyperplasia or adenoma, or rarely from parathyroid carcinoma. Pericentromeric inversion of chromosome 11 that results in activation of the P:RAD1/cyclin D1 gene and tumor suppressor gene loss have been described as genetic abnormalities in the evolution of parathyroid neoplasms. We studied tissue samples taken from primary parathyroid hyperplasia, parathyroid adenoma, and histologically normal parathyroid tissue by comparative genomic hybridization, fluorescent in situ hybridization, and immunohistochemistry for cyclin D1. DNA copy number changes were infrequent in primary hyperplasia (4 of 24, 17%), but common in adenomas (10 of 16, 63%; P: = 0.0059). The most common change was deletion of the entire chromosome 11 or a part of it, with a minimal common region at 11q23. This change was present in five (31%) adenomas and two (8%) primary hyperplasias. Fluorescent in situ hybridization confirmed the presence of both MEN1 alleles located at 11q13 despite deletion of 11q23 in all three cases studied. Cyclin D1 was overexpressed in six (40%) of the 15 adenomas studied, whereas none of the 27 hyperplasias (P: = 0.0010) nor the five histologically normal tissue samples overexpressed cyclin D1. Either DNA copy number loss or cyclin D1 overexpression was present in 13 (81%) of the 16 adenomas. We conclude that DNA copy number loss and cyclin D1 overexpression are common in parathyroid adenomas. The region 11q23 is frequently lost in parathyroid adenomas and occasionally in parathyroid hyperplasias, and this suggests the possibility that a tumor suppressor gene that is important in their pathogenesis is present on 11q23.     

A GT dinucleotide repeat polymorphism in intron 1 of the H-cadherin (CDH13) gene

A polymorphic dinucleotide (GT) repeat sequence was isolated from a genomic clone containing the human H-cadherin (CDH13) gene at 16q24.1-q24.2. This polymorphic marker will be a useful tool in the genetic study of various cancers. Received: July 24, 1998 / Accepted: July 29, 1998     

A new case of translocation t(6;11)(q21;q23) in a therapy-related acute myeloid leukemia resulting in an MLL–AF6q21 fusion

A new case of translocation t(6;11)(q21;q23) in a patient with therapy-related acute myeloblastic leukemia is reported. The translocation results in fusion of the MLL and AF6q21 genes. The breakpoint with AF6q21 is located within the sequences encoding the AF6q21 fork head motif. The similar location of the localization of the chromosome 6 breakpoints in the present case and in the first case reported suggests their nonrandom localization. In addition, treatment for Hodgkin's disease prior to leukemia in both t(6;11)(q21;q23) cases suggests an association of this translocation with therapy-related leukemias, as reported for the recently described t(11;16)(q23;p13.3). Genes Chromosomes Cancer 22:221–224, 1998. © 1998 Wiley-Liss, Inc.     

A nutrient-regulated cytosolic calcium oscillator in endocrine pancreatic glucagon-secreting cells

 We investigated the influence of nutrients on spontaneous cytosolic calcium oscillations in InR1-G9 glucagonoma cells, a model for pancreatic α-cells. The oscillations depended on calcium release from stores and on calcium influx, partly through voltage-dependent calcium channels. Oscillations required the presence of at least 1 mM glucose, 50 μM alanine, or 50 μM glutamine, but were terminated by higher nutrient concentrations (40 mM glucose, or above 2 mM alanine or glutamine). The effects depended on the metabolism of the nutrients. Glutamine and alanine hyperpolarized the cells. This effect was inhibited (glutamine) or attenuated (alanine) by 1 mM ouabain. Our findings suggest that [Ca²⁺]_i regulation in α-cells is dominated by slow oscillations induced by a lack of metabolic energy, resulting in decreased calcium export and storage, as well as increased calcium influx, partly due to depolarization caused by reduced sodium pump activity. These processes, leading to an elevated cytosolic calcium concentration, may mediate oscillations by calcium-induced calcium release from intracellular stores. Received: 24 June 1998 / Received after revision: 6 October 1998 / Accepted: 12 October 1998     

Bilateral multiple renal oncocytomas and cysts associated with a constitutional translocation (8;9)(q24.1;q34.3) and a rare constitutional VHL missense substitution

We report here on a patient with bilateral multifocal renal oncocytomas and cysts. Cytogenetic analysis of the patient's lymphocytes revealed a constitutional 46,XY,add (9)(q34.3) karyotype. The rearrangement was further resolved as a constitutional reciprocal t(8;9)(q24.1;q34.3) by microdissection and FISH. Because the 9q breakpoint was located in the same region as the tuberous sclerosis type 1 locus (TSC1), which is associated with renal tumors, we performed FISH with two TSC1 flanking cosmids that were mapped proximal to the 9q breakpoint, thus excluding its involvement. Loss of heterozygosity (LOH) studies of the tumors revealed LOH in chromosome 1, further strengthening the molecular diagnosis of oncocytoma. A previously unreported germline missense substitution, Pro40Arg, in exon 1 of the VHL gene was also found in the patient's constitutional DNA, adding to the complexity of the genetic profile. Genes Chromosomes Cancer 21:260–264, 1998. © 1998 Wiley-Liss, Inc.     

The time course of renal function and bone turnover in parathyroid crisis due to intratumoral hemorrhage

Parathyroid crisis occurring in primary hyperparathyroidism is characteized by extremely high circulating levels of parathyroid hormone and acute onset of severe hypercalcemia. We describe a 62-year-old woman with parathyroid crisis probably due to an intraturnoral hemorrhage. Renal dysfunction reduced the effectiveness of preoperative management and continued to deteriorate for 5 days after parathyroidectomy. The normalization of serum calcium after parathyroidectomy delayed and it took 6 days. Maintenance of renal function is important for pre- and postoperative courses of the present case. The rapid decrease in serum parathyroid hormone after parathyroidectomy was followed by a rapid and transient (about fivefold) increase in serum alkaline phosphatase with peak value on the 10th postoperative day. This indicated that reversal phase from bone resorption (accelerated by parathyroid hormone) to bone formation lasted about 10 days under the conditions of the present case.Abbreviations PTH parathyroid hormone - ALP alkaline phosphatase Correspondence to: K. Mizunashi     

Mapping of a new target region of allelic loss to a 6-cM interval at 21q21 in primary breast cancers

A detailed analysis of loss of heterozygosity (LOH) in breast cancers was performed with 11 microsatellite markers on the long arm of chromosome 21. Among the 142 tumors examined, 44 (31%) showed LOH at one or more loci. Peak LOH frequency was observed on band 21q21. Deletion mapping identified a new commonly deleted region in a 6-cM interval of 21q21 between loci D21S1432 and D21S1437, and raised the possibility that one or more tumor suppressor genes associated with breast cancer may exist in this region. Comparison of these alterations with clinicopathological parameters revealed an association of LOH on 21q with loss of progesterone receptor (P = 0.0013). Genes Chromosomes Cancer 23:244–247, 1998. © 1998 Wiley-Liss, Inc.     

Expression of the α- and β-subunits of human chorionic gonadotropin by subsets of parathyroid cells in states of hyperparathyroidism

The α-subunit of human chorionic gonadotropin (hCG-α) has previously been found to be expressed in hyperplasias and tumours of numerous endocrine tissues including all those involved in MEN-I syndrome except the parathyroid glands. In the present immunohistochemical investigation of 86 patients with various states of hyperparathyroidism, expression of hCG-α by subsets of parathyroid cells was shown in 46 cases (54 per cent) including all states of hyperparathyroidism investigated: primary adenoma (n=34, 44 per cent); uraemic secondary hyperplasia (n=34, 53 per cent); MEN-I (n=13, 77 per cent); MEN-II (n=2, 100 per cent); and parathyroid carcinoma (n=3, 100 per cent). Although the number of parathyroid cells expressing hCG-α was in general low, the occurrence of numerous immunoreactive cells appeared to be concentrated in primary adenoma and MEN-I (20 and 33 per cent of positive cases, respectively). No expression was found in ten normal control glands, except for very rare cells in one case. Expression of hCG-α was in part associated with that of hCG-β, which appeared to be more commonly expressed than hCG-α in cases of secondary hyperparathyroidism. In separate experiments, Bouin fixation was found to preserve the immunoreactivity of hCG-α and hCG-β better than the formalin fixation used in this study, suggesting that the figures may be underestimates. These immunohistochemical results are in agreement with a previous biochemical study showing hCG-α and hCG-β in extracts of parathyroid tumours and extend to the parathyroid glands the otherwise ubiquitous finding of hCG-α expression in MEN-I-related neoplasms. © 1998 John Wiley & Sons, Ltd.     

Characterization of a t(8;13)(p11;q11-12) in an atypical myeloproliferative disorder

Fourteen cases of an atypical myeloproliferative disorder associated with consistent translocations involving 8p11-12 have previously been described. A t(8;13)(p11;q11-12) was the most common, but variant t(8;9)(p11-12;q32-34) and t(6;8)(q27;p12) were also reported. Here we have used a series of yeast artificial chromosomes (YACs) derived from the 8p11 and 13q11-12 regions to analyse one of the t(8;13) cases by fluorescence in situ hybridization (FISH). YACs flanking the 13q11-12 breakpoint and spanning the 8p11 breakpoint have been isolated. These YACs will facilitate characterization of the genes involved in this rearrangement. Genes Chromosomes Cancer 21:70–73, 1998. © 1998 Wiley-Liss, Inc.