GH and PRL gene expression by nonradioisotopic in situ hybridization in TSH-secreting pituitary adenomas.

TSH-secreting pituitary adenomas are rare. The transcriptional expression (messenger ribonucleic acids: mRNAs) of TSH beta, GH, and PRL in five patients with TSH-secreting pituitary adenoma was studied by the in situ hybridization (ISH) method in order to elucidate their multiple hormone production. These patients showed inappropriately elevated serum TSH and alpha-subunit levels as well as pituitary mass lesions. The tissues from pituitary adenomas were obtained at the time of transsphenoidal surgery and revealed immunohistochemically the expression of alpha-subunit and TSH beta in all patients. Four adenomas were immunohistochemically associated with GH or PRL localization. The presence of pituitary-specific transcriptional factor Pit-1 was demonstrated in all adenomas in the nuclei of many cells. By ISH, signals for TSH beta mRNA were present in all five cases in many adenoma cells. Expression of GH mRNA and PRL mRNA were detected not only in four adenomas in which both hormonal products were immunolocalized but also in one adenoma that was immunohistochemically negative for GH and PRL. Combined staining by ISH and immunohistochemistry revealed the expression of GH mRNA and PRL mRNA in TSH beta-immunoreactive cells. Our findings indicate that TSH-secreting adenomas are multihormone-producing and could arise from precursor or stem cells rather than from differentiated TSH-secreting cells. It is suggested that ISH combined with immunohistochemistry may provide additional detailed information concerning the multidirectional histogenesis of this rare type of adenoma.

Pituitary somatotroph adenoma producing growth hormone (GH)-releasing hormone (GHRH) with an elevated plasma GHRH concentration: a model case for autocrine and paracrine regulation of GH secretion by GHRH.

An acromegalic patient with a pituitary somatotroph adenoma associated with an extremely elevated plasma GHRH concentration is presented. The preoperatively high concentration of plasma GHRH returned to the normal level after successful removal of the adenoma. GHRH production and GHRH gene expression were confirmed in the adenoma by studies including immunohistochemistry and in situ hybridization. Expression of GHRH receptor messenger ribonucleic acid was verified by in situ hybridization. Immunohistochemical double staining for GH and GHRH revealed their colocalization in single adenoma cells. These findings confirmed the autocrine or paracrine regulation of GH production by endogenous GHRH from the adenoma cells. GHRH synthesis in the pituitary gland has recently been demonstrated, however, there have been no previous reports of a GHRH-producing pituitary somatotroph adenoma associated with an elevated plasma GHRH concentration. The existence of this GHRH-producing adenoma suggests a possible role of locally generated GHRH in the progression of somatotroph adenomas, i.e. the monoclonally established somatotroph adenomas develop further under the influence of locally produced GHRH. The demonstration of GHRH production by this somatotroph adenoma is of importance in clarifying the autocrine or paracrine regulation of GH production and the progression of human somatotroph adenomas.

Cytochemical and molecular biological aspects of the pituitary and pituitary adenomas--cell differentiation and transcription factors.

The anterior pituitary is composed of several cell types, each responsible for the production of specific hormones. Each hormone secreting cells is defined by the activation of its respective hormone genes in a temporally and spatially regulated manner. Recent development in cytochemistry and molecular biology have provided various aspects of human pituitary adenomas, i.e., functional differentiation and classification. The molecular factors that determine hormone production have now been identified as transcription factors. Many novel transcription factors that play a role in anterior pituitary development are implicated. In this review, we focus on the transcriptional factors roles on functional differentiation of the pituitary cells and adenomas and the contribution of cytochemistry and recent development in molecular biological techniques.

Complete genomic sequence of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120.

The nucleotide sequence of the entire genome of a filamentous cyanobacterium, Anabaena sp. strain PCC 7120, was determined. The genome of Anabaena consisted of a single chromosome (6,413,771 bp) and six plasmids, designated pCC7120alpha (408,101 bp), pCC7120beta (186,614 bp), pCC7120gamma (101,965 bp), pCC7120delta (55,414 bp), pCC7120epsilon (40,340 bp), and pCC7120zeta (5,584 bp). The chromosome bears 5368 potential protein-encoding genes, four sets of rRNA genes, 48 tRNA genes representing 42 tRNA species, and 4 genes for small structural RNAs. The predicted products of 45% of the potential protein-encoding genes showed sequence similarity to known and predicted proteins of known function, and 27% to translated products of hypothetical genes. The remaining 28% lacked significant similarity to genes for known and predicted proteins in the public DNA databases. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome based on their similarity to the reported genes. One hundred and ninety-five genes coding for components of two-component signal transduction systems, nearly 2.5 times as many as those in Synechocystis sp. PCC 6803, were identified on the chromosome. Only 37% of the Anabaena genes showed significant sequence similarity to those of Synechocystis, indicating a high degree of divergence of the gene information between the two cyanobacterial strains.

Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti.

The complete nucleotide sequence of the genome of a symbiotic bacterium Mesorhizobium loti strain MAFF303099 was determined. The genome of M. loti consisted of a single chromosome (7,036,071 bp) and two plasmids, designated as pMLa (351,911 bp) and pMLb (208, 315 bp). The chromosome comprises 6752 potential protein-coding genes, two sets of rRNA genes and 50 tRNA genes representing 47 tRNA species. Fifty-four percent of the potential protein genes showed sequence similarity to genes of known function, 21% to hypothetical genes, and the remaining 25% had no apparent similarity to reported genes. A 611-kb DNA segment, a highly probable candidate of a symbiotic island, was identified, and 30 genes for nitrogen fixation and 24 genes for nodulation were assigned in this region. Codon usage analysis suggested that the symbiotic island as well as the plasmids originated and were transmitted from other genetic systems. The genomes of two plasmids, pMLa and pMLb, contained 320 and 209 potential protein-coding genes, respectively, for a variety of biological functions. These include genes for the ABC-transporter system, phosphate assimilation, two-component system, DNA replication and conjugation, but only one gene for nodulation was identified.

Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. II. Sequence determination of the entire genome and assignment of potential protein-coding regions.

The sequence determination of the entire genome of the Synechocystis sp. strain PCC6803 was completed. The total length of the genome finally confirmed was 3,573,470 bp, including the previously reported sequence of 1,003,450 bp from map position 64% to 92% of the genome. The entire sequence was assembled from the sequences of the physical map-based contigs of cosmid clones and of lambda clones and long PCR products which were used for gap-filling. The accuracy of the sequence was guaranteed by analysis of both strands of DNA through the entire genome. The authenticity of the assembled sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA using the assembled sequence data. To predict the potential protein-coding regions, analysis of open reading frames (ORFs), analysis by the GeneMark program and similarity search to databases were performed. As a result, a total of 3,168 potential protein genes were assigned on the genome, in which 145 (4.6%) were identical to reported genes and 1,257 (39.6%) and 340 (10.8%) showed similarity to reported and hypothetical genes, respectively. The remaining 1,426 (45.0%) had no apparent similarity to any genes in databases. Among the potential protein genes assigned, 128 were related to the genes participating in photosynthetic reactions. The sum of the sequences coding for potential protein genes occupies 87% of the genome length. By adding rRNA and tRNA genes, therefore, the genome has a very compact arrangement of protein- and RNA-coding regions. A notable feature on the gene organization of the genome was that 99 ORFs, which showed similarity to transposase genes and could be classified into 6 groups, were found spread all over the genome, and at least 26 of them appeared to remain intact. The result implies that rearrangement of the genome occurred frequently during and after establishment of this species.

Applications of plastic embedding to electron microscopic immunocytochemistry and in situ hybridization in observations of production and secretion of peptide hormones.

Plastic embedding has been used to localize various antigens in conjunction with immunohistochemistry. Peptide hormones have been among the antigens that have been studied extensively. Recent application of water-soluble plastics such as LR White and Lowicryl has extended the ranges of detectable antigens and enabled the observation of antigen-antigen or mRNA-antigen combinations. This review article deals with technical aspects, procedures, and applications in endocrine cells.

Contributions of immunohistochemistry and in situ hybridization to the functional analysis of pituitary adenomas.

Immunohistochemistry (IHC) and recently in situ hybridization (ISH) have elucidated various aspects of human pituitary adenomas, i.e., functional differentiation and classification, transcription factors and mechanism of hormone production, regulation of hormone secretion, and processing of prohormones. Recently, the use of tyramide (catalyzed signal amplification; TSA or CSA) and RT-PCR has been effective for detection of trivial amount of proteins (peptides) and mRNA, respectively. Immunomolecular histochemistry is expected to further clarify the function and biology of human pituitary adenomas.

Modulation of protein kinases and microtubule-associated proteins and changes in ultrastructure in female rat pituitary cells: effects of estrogen and bromocriptine.

This study focused on the intracellular signal transduction system and microtubule-associated proteins (MAPs), such as MAP-2 and Tau protein. The modulation of these proteins and their correlation with ultrastructural changes were investigated in rat pituitary prolactin (PRL) cells. Adult female Wistar rats were treated with estrogen and bromocriptine and their pituitary glands were removed for analysis of the expression of tubulin, MAP-2, Tau protein, protein kinase C (PKC), and calcium calmodulin (CaM) kinase. Western blot analysis showed that estrogen increased and bromocriptine decreased the expression of PKC alpha, beta 1, beta 2, CaM kinase alpha, beta, MAP-2, and Tau protein. MAP-2 and Tau protein, which are cytosolic proteins, being translated on free ribosomes, were associated with the membrane of whirling rough endoplasmic reticulum (RER) in estrogen-treated cells and dissociated with vesiculated RER induced by bromocriptine. These results suggested that the modulation of MAP-2 and Tau protein may reflect changes of PKC and CaM kinase, and that the quantitative changes and intracellular modulation of MAPs induced by estrogen and bromocriptine, i.e., estrogen-induced association and bromocriptine-induced dissociation of MAP-2 and Tau protein with membrane of RER, may reflect the dynamics of microtubules and are associated with structural changes in the RER and changes in the synthesis and intracellular transport of PRL.

Transcavernous surgery; an effective treatment for pituitary macroadenomas.

The endocrinological outcome in four patients with pituitary macroadenomas laterally invading the cavernous sinus, who were treated surgically by the transcranial transcavernous approach, was compared with that in four patients with macroadenomas that had been removed transsphenoidally. The decrease in the elevated serum levels of anterior pituitary hormones after transcavernous surgery ranged from 58.4% to 90.1%, whereas after transsphenoidal surgery it ranged from 0% to 46.1%. The responsiveness of pituitary hormones to stimulation tests was restored and maintained after transcranial transcavernous surgery. Transsphenoidal surgery achieved neither sufficient tumor reduction nor produced a satisfactory endocrinological remission. When cavernous sinus invasion is suspected by magnetic resonance imaging, even if it cannot be confirmed with certainty, transcranial transcavernous surgery is recommended. It is a useful surgical procedure for obtaining a sufficient degree of tumor extirpation and satisfactory endocrinological improvement in patients with macroadenomas laterally invading the cavernous sinus, particularly somatotroph or corticotroph macroadenomas. Postoperatively, mild cranial nerve paresis may occur, but this may resolve in 1-4 months.

Immunohistochemical examination of proliferative potentials and the expression of cell cycle-related proteins of intracranial chordomas.

The difference in biological features between recurrent and nonrecurrent intracranial chordomas has not been studied. In this study, proliferative potentials of chordomas were studied with an immunohistochemical staining method, mainly using anti-Ki-67 antibody, MIB-1, which is known to be available for archival paraffin sections, together with immunohistochemical studies on the expression of cell cycle or apoptosis-related proteins, including p53, cyclin D1, and bcl-2 proteins. The correlation among MIB-1 staining indices, the immunoreactivities of these proteins, and clinical courses of intracranial chordomas were analyzed retrospectively, and the statistically significant correlation between MIB-1 staining index (SI) and recurrence has been clarified. The mean MIB-1 SI of recurrent tumors was 10.2%, being shown to be higher than that of nonrecurrent tumors (2.8%). The immunohistochemically positive staining of cell cycle-related protein, especially p53 and cyclin D1 proteins, correlated well with recurrence and high MIB-1 SI. In conclusion, both the examination of proliferative potentials of chordomas using MIB-1 SI and the study of the immunoreactivity of p53 and cyclin D1 proteins are important for their biological and histopathological analyses and the prediction of future recurrence.

Growth hormone-releasing hormone expression in pituitary somatotroph adenomas, studied by immunohistochemistry and in situ hybridization using catalyzed signal amplification system.

Growth hormone-releasing hormone (GHRH) is a well-known hypothalamic hormone that stimulates the synthesis and release of growth hormone (GH) as well as the proliferation of GH-producing cells in the anterior pituitary gland. Recent reports have shown GHRH synthesis in pituitary somatotroph adenomas, but GHRH immunoreactivity has not been shown in previous studies. To confirm the role of locally generated GHRH for the progression of somatotroph adenomas, we investigated the expression of GHRH in 25 pituitary somatotroph adenomas immunohistochemically, through the use of both conventional avidin-biotin-complex (ABC) method and novel catalyzed signal amplified (CSA) system. In addition, we investigated the expression of GHRH mRNA and GHRH receptor mRNA with in situ hybridization (ISH) using the CSA system. The weak immunopositivity of GHRH was observed in only 2 adenomas (8.0%) of 25 somatotroph adenomas using the ABC method. In contrast, 15 adenomas (60.0%) of 25 somatotroph adenomas were immunopositive for GHRH, as shown by CSA system. Very few of nonsomatotroph adenomas were immunopositive for GHRH using the CSA system. The expression of GHRH mRNA was confirmed, using the CSA-ISH system in 13 adenomas (72.2%) of 18 somatotroph adenomas. In 11 adenomas (61.1%) of 18 somatotrophic adenomas, the expression of GHRH receptor mRNA was demonstrated using the CSA-ISH system. This is a first report that clarified histopathologically GHRH production in pituitary somatotrophic adenomas. The demonstration of GHRH and its receptor expression is meaningful in clarifying the autocrine or paracrine regulation of GHRH in GH production and progression of pituitary somatotroph adenomas.

Expression of plurihormonal mRNAs in somatotrophic adenomas detected using a nonisotopic in situ hybridization method: comparison with lactotrophic adenomas.

We used a nonisotopic in situ hybridization (ISH) method to investigate the expression of pituitary hormone, including glycoprotein hormone mRNAs in 17 somatotrophic and four lactotrophic adenomas. Our ISH studies of lactotrophic adenomas showed that their hormonal gene expression was confined to prolactin, whereas those of somatotrophic adenomas showed that some of them expressed plurihormonal genes. In some somatotrophic adenomas that were immunohistochemically negative for pituitary hormones, positive reactions, mainly for adrenocorticotropic hormone (ACTH), follicle-stimulating hormone beta subunit (FSH beta), and luteinizing hormone beta subunit (LH beta) mRNAs, were observed in our ISH studies. These results suggest that some somatotrophic adenomas may originate from plurihormonal primordial stem cells, which we have presumed serve as precursors for various hormone-expressing cells. It is unclear why some somatotrophic adenomas derived from plurihormonal primordial stem cells manifest clinically only as the acromegalic hyperfunction syndrome or gigantism. Additional translational factors or some other somatic mutations may play important roles in the clinical manifestations of such adenomas. In conclusion, some somatotrophic adenomas appear to be derived from plurihormonal primordial stem cells, whereas lactotrophic adenomas are well differentiated tumors that originate from lactotrophic cells, which represent the final stage of acidophilic cell line differentiation.

Correlation between MIB-1 staining index and the immunoreactivity of p53 protein in recurrent and non-recurrent meningiomas.

Wild type p53 protein has been shown by recent investigations to be involved in the negative regulation of cell proliferation, whereas aberrant p53 protein has lost this negative regulation of cell growth. Wild type p53 protein, which has a very short half-life, has generally been considered to be undetectable using immunohistochemical methods; however, according to a recent report, wild type p53 protein may accumulate in the nuclei because of a defective ubiquitin pathway. Aberrant p53 protein has a longer half-life, and thus is visible using immunohistochemical methods. In this study, both the proliferative potential represented by the MIB-1 staining index (SI) and the immunoreactivity of p53 protein in 51 intracranial meningiomas were studied applying immunohistochemical staining methods to archival paraffin sections. The correlation among MIB-1 SI, p53 immunoreactivity, histopathologic findings and the clinical course of the meningiomas was also analyzed retrospectively. Although it is not possible with available reagents to distinguish between aberrant p53 protein and wild type p53 protein, statistical analyses show that p53 protein was immunostained both in meningiomas with high MIB-1 SI and in recurrent meningiomas. This demonstrates the close relationship among p53 immunoreactivity, MIB-1 SI, and recurrence; therefore, the presence of p53 protein by immunohistochemical examination may suggest the proliferative activity of meningioma and is capable of serving as a predictor of future recurrence.

Electron microscopic observation of intracellular expression of mRNA and its protein product: technical review on ultrastructural in situ hybridization and its combination with immunohistochemistry.

In situ hybridization (ISH) at the electron microscopic (EM) level is essential for elucidating the intracellular distribution and role of mRNA in protein synthesis. Three different approaches have been applied by the investigators in this EM-ISH study: preembedding method; non-embedding method using ultrathin frozen sections; and postembedding method. In order to obtain satisfactory morphological preservation and retain the messages, we routinely utilized 6 microns-thick frozen sections fixed in 4% paraformaldehyde for the preembedding method and tissues embedded in LR White resin for the postembedding method. The hybridization signal intensity by the postembedding method was lower, and non-specific signals were relatively frequent, in comparison with the preembedding method. The preembedding method thus appears to be easier and better than the postembedding method from the viewpoint of applicability and preservation of mRNA, although quantitative analysis of the expression of mRNA is rather difficult in the preembedding method. EM-ISH is considered to be an important tool for clarifying the intracellular localization of mRNA and the exact site of specific hormone synthesis on the rough endoplasmic reticulum. The simultaneous visualization of mRNA and encoded protein in the same cells using preembedding EM-ISH and subsequent postembedding immunoreaction with protein A colloidal gold complex is also described. This ultrastructural double-staining method for mRNA and encoded protein can be expected to provide an important clue for elucidating the intracellular correlation of mRNA translation and secretion of translated protein.

Proliferative activity and p53 protein accumulation correlate with early invasive trend, and apoptosis correlates with differentiation grade in oesophageal squamous cell carcinomas.

Using oesophageal squamous cell carcinoma samples of both intramucosal and advanced types, proliferative activity (Ki-67 labelling index), p53 protein accumulation and apoptosis (in situ DNA nick end labelling) were assessed, and the relation of these values to progression or differentiation grade of tumours was analysed. In terms of proliferative activity and the proportion of positive cases with p53 accumulation, a statistically significant difference was demonstrated between intraepithelial carcinomas and intramucosal carcinomas with stromal invasion (17.2% vs 31.7% for the Ki-67 labelling index, and 23.5% vs 67.4% for the proportion of positive cases of p53 accumulation). Values for the latter were almost comparable to those of advanced carcinomas. Immunohistologically, Ki-67 positive, proliferating cells were distributed preferentially in the peripheral fronts of invading nests. Apoptotic cells were observed in the inner areas of the invading nests of the intramucosal carcinomas with stromal invasion and in more advanced lesions, but were rarely observed in the normal epithelium or intraepithelial carcinomas. Apoptotic cells were seen mainly around areas of keratinization, and the apoptotic cell index was higher in well and moderately differentiated types of advanced carcinomas than in the poorly differentiated type (2.59% vs 1.09%). An increase in proliferative activity and an accumulation of p53 protein are associated with the onset of early carcinomatous invasion, while apoptosis is closely linked with the differentiation grade of carcinoma cells.

Expression of the cyclin dependent kinase inhibitor p21WAF1/CIP1 in oesophageal squamous cell carcinomas.

To elucidate the role of CDK inhibitor p21WAF1/CIP1 in human oesophageal squamous cell carcinomas, we examined its expression immunohistochemically using surgically resected tissues from 25 patients, and have analyzed the relationship with alteration of p53 gene (F-SSCP analysis), proliferative activity (Ki-67 labelling index), frequency of apoptosis (in situ DNA nick end labelling), and degree of differentiation. P21 expression was observed in 11 cases (44%) with a percentage of positive cells ranging between 1% and 10%. Of the 25 cases, 4 cases showed > 5% of positive cells. As for the relationship with p53 gene, all 7 p53-mutation positive cases were negative for p21 expression, whereas 11 out of 18 mutation negative cases showed positive for p21 expression. As for the relationship with degree of tumour differentiation, 6 out of 8 well differentiated type cases showed positive for p21 expression. By contrast, all 8 cases of poorly differentiated type were negative for p21 expression. Frequency of apoptotic cells was significantly higher in p21 positive cases than negative cases although Ki-67 labelling index was almost the same regardless of the expression of p21. P21 expressing cells were distributed mainly in the middle layers of the invading nests, especially around the keratinization, which was almost similar to the distribution of apoptotic cells. Our results suggest that expression of p21 in human oesophageal squamous cell carcinomas is induced by a p53-dependent pathway and affects apoptosis and differentiation of carcinoma cells.

Application of confocal laser scanning microscopy (CLSM) to visualize prolactin (PRL) and PRL mRNA in the normal and estrogen-treated rat pituitary glands using non-fluorescent probes.

In the present study, we performed concomitant visualization of immunohistochemistry (IHC) and in situ hybridization (ISH) on the materials processed for conventional light microscopic specimens using non-fluorescent Confocal Laser. Scanning Microscopy (CLSM). CLSM was used in the reflection confocal mode using horseradish peroxidase (HRP)-3-3'diaminobenzidine (DAB)-osmium (osmium black) and nitroblue tetrazolium (NBT) as non-fluorescent detection methods (probes). To obtain clearer images of the organelles, images that were built up as electronic signals in CLSM were processed in an image analysis system (IAS). By using the combination of CLSM and IAS, in IHC, immunohistochemical localization of prolactin (PRL) was in well-developed lamellar or whorling rough endoplasmic reticula (RER), Golgi apparatus, and secretory granules. With ISH, the expression and distribution of PRL messenger ribonucleic acid (mRNA) was observed in a fashion suggesting polysome-like structures on RER. These observations were confirmed by immunoelectron microscopy and electron microscopic ISH. The herein-described method is expected to be useful to perform the concomitant observation of IHC and ISH at subcellular levels using the conventional light microscopic specimens.

Systemic cytomegalovirus infection during postoperative chemoradiotherapy for malignant astrocytoma: case report with immunohistochemistry and in situ hybridization.

We report a patient with a systemic cytomegalovirus (CMV) infection, which occurred during postoperative chemoradiotherapy for a malignant astrocytoma. To our knowledge, there is no report that is especially focused on the association with a CMV infection. Interstitial pneumonia and gastrointestinal bleeding, which developed suddenly during postoperative chemoradiotherapy, resulted in the patient's death. A histopathological examination of the postmortem specimens revealed numerous "owl's eye" cells containing intranuclear inclusion bodies, which were identified as CMV by immunohistochemical examination and in situ hybridization. The premortem diagnosis of CMV infection is usually difficult, because an anti-CMV titer can be nonspecifically elevated. With immunohistochemical examination and in situ hybridization, CMV in excretory or biopsy specimens can be identified and the diagnosis of CMV infection can be established. When serious pneumonia or massive gastrointestinal bleeding occurs during postoperative chemoradiotherapy, the differential diagnosis should include the possibility of CMV infection and we recommend an immunohistochemical examination and in situ hybridization for the detection of CMV.

Gigantism in sibling unrelated to multiple endocrine neoplasia: case report.

The cases of gigantism sisters with somatotroph adenomas unrelated to multiple endocrine neoplasia (MEN) Type 1 are reported. The sisters grew rapidly since they were 5 or 6 years old and were diagnosed to have gigantism with pituitary adenoma by computed tomographic scan and magnetic resonance imaging. A serum endocrinological examination showed the elevated growth hormone values. After thyroxine-releasing hormone stimulation, growth hormone values exhibited a paradoxical rise. They were supposed to be unrelated to MEN Type 1, because analysis of the 11th chromosomes and the other endocrine functions were normal. They were operated on by the transphenoidal method. Immunohistochemical staining of both tumor specimens confirmed somatotroph adenomas. Pituitary adenoma associated with MEN Type 1 is a well-recognized entity. However, the sporadic occurrence of pituitary adenoma unrelated to MEN Type 1, especially in siblings, is extremely rare. Fifteen cases of pituitary adenomas in siblings were described in the literature. As for gigantism, only two brothers were reported. Our case of gigantism sisters is the second sporadic case. In our review of the isolated cases of pituitary adenoma in siblings described in the literature, 12 (70%) of 17 cases including ours are acromegaly or gigantism. This incidence is much higher than that of MEN Type 1 patients with pituitary adenomas. The cause of the familial occurrence of pituitary adenomas is still unclear, although autosomal recessive inheritance has been suggested. It has been stated that point mutations in codon 201 or 227 of the Gs alpha gene located in chromosome 20 were found in about 35 to 40% of somatotroph adenomas.(ABSTRACT TRUNCATED AT 250 WORDS)