Transplant-associated thrombotic microangiopathy and immune haematological complications following intestine-containing organ transplantation: experience from over 100 consecutive cases.

Descriptions of passenger lymphocyte syndrome (PLS), immune cytopenias and transplant-associated thrombotic microangiopathy (TA-TMA) after intestine-containing transplants remain scarce. We describe our centre's experience of these complications from 2007 to 2019. Ninety-six patients received 103 transplants. PLS occurred in 9 (9%) patients (median 12 days post-transplant); all due to ABO antibodies. There were 31 minor ABO mismatch transplants. No patient required change in immunosuppression. Immune cytopenias (excluding PLS) occurred in six patients at an incidence of 1·7/100 patient years; three immune haemolysis, one immune thrombocytopenia, one acquired Glanzmann's and one immune neutropenia; 50% occurred with other cytopenias. All cases eventually responded to treatment, with a median of four treatments (range 1-8) and 5/6 were treated with rituximab. One patient with immune haemolysis required bortezomib. Complications were common in patients with immune cytopenias; 4/6 with infection needing intravenous antibiotics and 3/6 with venous thromboembolism. In 3/6 cases, a secondary cause for the immune cytopenia was evident. Switching from tacrolimus to ciclosporin was not necessary. There were five cases of transplant-associated thrombotic microangiopathy (TA-TMA; 1·5/100 patient years) requiring calcineurin inhibitor withdrawal; two cases associated with acute rejection. Two cases were managed with plasma exchange, one with plasma infusions and one with eculizumab. Further research in this patient group is required.

Characterisation of proguanylin expressing cells in the intestine - evidence for constitutive luminal secretion.

Guanylin, a peptide implicated in regulation of intestinal fluid secretion, is expressed in the mucosa, but the exact cellular origin remains controversial. In a new transgenic mouse model fluorescent reporter protein expression driven by the proguanylin promoter was observed throughout the small intestine and colon in goblet and Paneth(-like) cells and, except in duodenum, in mature enterocytes. In Ussing chamber experiments employing both human and mouse intestinal tissue, proguanylin was released predominantly in the luminal direction. Measurements of proguanylin expression and secretion in cell lines and organoids indicated that secretion is largely constitutive and requires ER to Golgi transport but was not acutely regulated by salt or other stimuli. Using a newly-developed proguanylin assay, we found plasma levels to be raised in humans after total gastrectomy or intestinal transplantation, but largely unresponsive to nutrient ingestion. By LC-MS/MS we identified processed forms in tissue and luminal extracts, but in plasma we only detected full-length proguanylin. Our transgenic approach provides information about the cellular origins of proguanylin, complementing previous immunohistochemical and in-situ hybridisation results. The identification of processed forms of proguanylin in the intestinal lumen but not in plasma supports the notion that the primary site of action is the gut itself.

Fatal breakthrough mucormycosis in a multivisceral transplant patient receiving micafungin: Case report and literature review.

Introduction: Antifungal agents are routinely used in the post-transplant setting for both prophylaxis and treatment of presumed and proven fungal infections. Micafungin is an echinocandin-class antifungal with broad antifungal cover and favorable side effect profile but, notably, it has no activity against molds of the order Mucorales. Presentation of case: A 47-year-old woman underwent multivisceral transplantation for intestinal failure-associated liver disease. She had a prolonged post-operative recovery complicated by invasive candidiasis and developed an intolerance to liposomal amphotericin B. In view of her immunosuppression, she was commenced on micafungin as prophylaxis to prevent invasive fungal infection. However, she developed acute graft versus host disease with bone marrow failure complicated by disseminated mucormycosis which was only diagnosed post mortem. Discussion: Non-Aspergillus breakthrough mold infections with micafungin therapy are rare with only eight other cases having been described in the literature. Breakthrough infections have occurred within one week of starting micafungin. Diagnosis is problematic and requires a high degree of clinical suspicion and microscopic/histological examination of an involved site. The management of these aggressive infections involves extensive debridement and appropriate antifungal cover. Conclusion: A high level of suspicion of invasive fungal infection is required at all times in immunosuppressed patients, even those receiving antifungal prophylaxis. Early biopsy is required. Even with early recognition and aggressive treatment of these infections, prognosis is poor.

Graft versus host disease after multivisceral transplantation: A UK center experience and update on management.

Graft versus host disease (GVHD) following transplantation of an intestine-containing graft occurs more frequently than with other solid organ transplants and is known to have a poor outcome. The presentation differs from other solid organ transplants, as the gastrointestinal tract is not involved following intestinal transplant. Diagnosis is based on clinical symptoms arising due to native tissue damage and the detection of donor T lymphocytes in circulating blood (T-cell chimerism). The ideal treatment strategy has not been defined, with advocates for both increased and decreased immunosuppression. We reviewed all cases of GVHD in an adult intestinal transplant center in the United Kingdom and report on management strategies of five cases and methods of detecting T-cell chimerism. The practice in our center has evolved with experience. The first two patients received an increase in immunosuppression, which was only successful in one case. Subsequently, reducing immunosuppression has been more effective. However, patients with bone marrow involvement have a poorer prognosis. We demonstrate successful treatment of GVHD after multivisceral transplant with a reduction in immunosuppression. This should be followed by vigilant graft surveillance and serial monitoring of the level of T-cell chimerism, with reintroduction of immunosuppression at the earliest sign of graft dysfunction.

Urgent Multivisceral Transplantation for Widespread Splanchnic Ischemia.

BACKGROUND: Multivisceral transplantation (transplantation of the stomach, intestine, liver, and pancreas) is usually undertaken as a semi-elective procedure after thorough assessment in patients who have intestinal failure with cirrhosis, cirrhosis with portomesenteric venous thrombosis, or tumors such as desmoids involving the liver and mesentery. STUDY DESIGN: Data were collected prospectively from the time of referral and held in a central database. We used it to report the first cases of urgent multivisceral transplantation (MVT) in patients with widespread splanchnic ischemia (occlusion of the celiac axis and superior mesenteric artery) resulting in small bowel infarction and hepatic failure. RESULTS: Three women (ages 33, 48, and 50 years) were referred to our center with superior mesenteric artery and celiac axis occlusion. All other modes of treatment had been considered and/or attempted. After transfer to our institution, all patients were assessed, urgently listed, and underwent transplantation in 10, 7, and 5 days. Two patients are still alive after 2 years and 1 died at 8 months from multiorgan failure due to infections and graft vs host disease. CONCLUSIONS: Treatment options for patients presenting with widespread splanchnic ischemia with hepatic and intestinal failure/infarction were previously limited to salvage surgery and attempted revascularization. In situations in which these failed, the only previous option would have been palliation. In selected cases, we propose that urgent multivisceral transplantation should be considered as a life-saving treatment. This represents a previously unreported indication for MVT.

Delayed dynamic abdominal wall closure following multi-visceral transplantation.

INTRODUCTION: Primary closure of the abdominal wall following intestinal transplantation or multivisceral transplantation could become a challenging problem in a significant number of patients. PRESENTATION OF CASE: A 38-year-old woman with familial adenomatous polyposis (FAP) underwent a multi-visceral transplantation for short gut syndrome. She subsequently developed acute graft rejection that proved resistant to conventional treatment. She was relisted and underwent re-transplantation along with kidney transplantation. Abdominal wall closure could not be achieved because of the large size of the graft and bowel oedema. The wound was initially managed with laparostomy followed by insertion of the delayed dynamic abdominal closure (DDAC) device (Abdominal Retraction Anchor - ABRA(®) system). Continuous dynamic traction to the wound edges resulted in gradual approximation and complete closure of the abdominal wound was achieved within 3 weeks. DISCUSSION: Successful abdominal closure after multivisceral transplantation or isolated intestinal transplantation often requires biological mesh, vascularised flaps or abdominal wall transplantation. DDAC eliminated the need for a prosthetic mesh or skin graft and provided an excellent cosmetic result. Adjustment of the dynamic traction at the bedside minimised the need for multiple returns to the operating theatre. It resulted in a well-healed linear scar without a hernia. CONCLUSION: Dynamic traction allows delayed closure of laparotomy resulting in strong and cosmetically sound wound healing with native tissue.

Combination therapy with infliximab and azathioprine is superior to monotherapy with either agent in ulcerative colitis.

BACKGROUND & AIMS: The comparative efficacy and safety of infliximab and azathioprine therapy alone or in combination for ulcerative colitis (UC) have not been evaluated previously. METHODS: This randomized, double-blind trial evaluated the efficacy and safety of 16 weeks of treatment with infliximab monotherapy, azathioprine monotherapy, or the 2 drugs combined in tumor necrosis factor-a antagonist-naive adults with moderate to severe UC. Patients were assigned randomly to receive intravenous infusions of infliximab 5 mg/kg at weeks 0, 2, 6, and 14 plus daily oral placebo capsules; oral azathioprine 2.5 mg/kg daily plus placebo infusions on the infliximab schedule; or combination therapy with the 2 drugs. Corticosteroid-free clinical remission (primary end point, week 16) was evaluated at weeks 8 and 16. The study was terminated before the enrollment target was reached. RESULTS: A total of 239 patients were included in efficacy analyses. Baseline characteristics were similar between treatment groups. Corticosteroid-free remission at week 16 was achieved by 39.7% (31 of 78) of patients receiving infliximab/azathioprine,compared with 22.1% (17 of 77) receiving infliximab alone(P =.017) and 23.7% (18 of 76) receiving azathioprine alone(P =.032). Mucosal healing at week 16 occurred in 62.8% (49 of 78) of patients receiving infliximab/azathioprine, compared with 54.6% (42 of 77) receiving infliximab (P = .295) and 36.8% (28 of 76) receiving azathioprine (P =.001). Serious infections occurred in 2 patients (1 patient receiving infliximab,and 1 patient receiving azathioprine). CONCLUSIONS: Anti­tumor necrosis factor-a­naive patients with moderate to severe UC treated with infliximab plus azathioprine were more likely to achieve corticosteroid-free remission at 16 weeks than those receiving either monotherapy. Combination therapy led to significantly better mucosal healing than azathioprine monotherapy. ClinicalTrials.gov number, NCT00537316.

Use of the alpha glucosidase inhibitor acarbose in patients with 'Middleton syndrome': normal gastric anatomy but with accelerated gastric emptying causing postprandial reactive hypoglycemia and diarrhea.

Postprandial reactive hypoglycemia, early satiety and diarrhea are well-recognized side effects following full or partial gastrectomy or gastric bypass. It has only recently been realized, however, that patients with normal gastric anatomy may experience similar symptoms and signs due to primary accelerated gastric emptying (Middleton syndrome). In previous case studies, patients responded well to the use of dietary modification (frequent small-volume meals) alone. The authors describe two patients with this syndrome who continued to experience symptoms of reactive postprandial hypoglycemia despite dietary intervention but became asymptomatic following the addition of the alpha-glucosidase inhibitor acarbose.

Preoperative comorbidity correlates inversely with survival after intestinal and multivisceral transplantation in adults.

We investigated the relationship between preoperative comorbidity and postoperative survival after intestinal transplantation. Each patient received a score for preoperative comorbidity. Each comorbidity was given a score based on the degree it impaired function (score range 0-3). A total score was derived from the summation of individual comorbidity scores. Patients (72 adults (M : F, 33 : 39)) received an isolated intestinal graft (27) or a cluster graft (45). Mean (standard deviation) survival was 1501 (1444) days. The Kaplan-Meier analysis revealed a significant inverse association between survival and comorbidity score (logrank test for trend, P < 0.0001). Patients grouped into comorbidity scores of 0 and 1, 2 and 3, 4 and 5, 6, and above had hazard ratios (95% confidence intervals) for death (compared to group 0 + 1), which increased with comorbidity scores: 1.945 (0.7622-5.816), 5.075 (3.314-36.17), and 13.77 (463.3-120100), respectively, (P < 0.0001). Receiver-operator curves at 1, 3, 5, and 10 years postoperative had "C" statistics of 0.88, 0.85, 0.88, and 0.92, respectively. When evaluating patients for transplantation, the degree of comorbidity should be considered as a major factor influencing postoperative survival.

An estimate of syphilis incidence in Eastern Europe.

AIM: Eastern Europe experienced epidemic levels of syphilis after the collapse of the Soviet Union. Presently data are less comprehensive outside the European Union (EU) and European Free Trade Association (EFTA). This review aims to identify published papers with suitable data to estimate a regional burden of disease for syphilis in the 19 member countries of Eastern Europe. METHODS: A systematic literature review was conducted to identify published data relating to syphilis incidence in Eastern Europe through Web of Knowledge, PubMed and Google Scholar databases in addition to the latest surveillance report from the European Center for Disease Prevention and Control. A total of 381 papers fitted our search criteria; 30 papers were subjected to full text analysis. RESULTS: Seven papers were included in this study and provided useable data for 13 out of 19 member countries. There was a high level of heterogeneity observed in the incidence rates from the member countries. Gross, population weighted and geographically subdivided incidence rate estimates were carried out but the comprehensiveness of some of the included data is doubtful. CONCLUSIONS: Despite the limits of the data, the incidence of syphilis in Eastern Europe is still substantially larger than that observed in the EU15 countries. This indicates that efforts to control syphilis in Eastern Europe can be enhanced; however, such goals would require significant investment in infrastructure, technology and surveillance mechanisms.

Idiopathic accelerated gastric emptying presenting in adults with post-prandial diarrhea and reactive hypoglycemia: a case series.

INTRODUCTION: We have previously reported the association of gastrointestinal and hypoglycemic symptoms, with idiopathic accelerated gastric emptying. We now report the first series of six similar cases. CASE PRESENTATIONS: Patient 1: A 24-year-old Caucasian man presented to our facility with a six-month history of post-prandial nausea, flatulence, bloating, abdominal discomfort and associated diarrhea. He had associated episodes of fatigue, sweating, anxiety, confusion and craving for sweet foods. Patient 2: A 52-year-old Caucasian woman presented to our facility with a 15-year history of post-prandial bloating, abdominal pain and diarrhea, often associated with nausea, severe sweating, and fatigue. Patient 3: An 18-year-old Caucasian woman presented to our facility with a nine-year history of post-prandial diarrhea, abdominal bloating and pain. There was associated nausea, tremor, lethargy, and craving for sweet foods. Patient 4: A 77-year-old Caucasian woman presented to our facility with a four-month history of epigastric distension, pain after eating and a change in bowel habit. She experienced intermittent severe diarrhea and marked fatigue, nausea and sweating. Patient 5: A 23-year-old Caucasian woman presented to our facility with a two-year history of early satiety, and diarrhea after eating. She also complained of feeling faint and weak between meals, when she became cold and clammy, and on several occasions lost consciousness during these episodes. Patient 6: A 64-year-old Caucasian woman presented to our facility with a 10-year history of nausea, early satiety and profound bloating followed by diarrhea. All symptoms predominantly occurred in the first three hours after eating, when she felt faint, lethargic, and had a craving for sweet foods. In all cases, symptoms were alleviated or resolved by taking sweet food or drink and response to treatment was 90% or greater in all cases. CONCLUSIONS: This series extends our description of this new clinical syndrome. All patients responded well to treatment for accelerated gastric emptying. Clinicians in the disciplines of endocrinology, gastroenterology, neurology and general practice are likely to find this information useful as they will consult patients with some or all of these symptoms and in a proportion of these patients idiopathic accelerated gastric emptying may be present and provide a useful avenue for therapeutic intervention.

Clinical significance of scintigraphic rapid gastric emptying.

OBJECTIVES: To analyse our results of gastric-emptying scintigraphy in relation to presenting symptoms, and examine in detail the clinical significance of rapid gastric emptying (RGE). MATERIALS AND METHODS: Results of 642 consecutive patients who underwent a solid gastric-emptying scintigraphy in our department over an 11-year period were retrospectively reviewed with particular emphasis to the presenting symptoms and the clinical profile of patients, especially of those who showed an accelerated pattern of emptying. RESULTS: Seventy (11%) patients were clinically suspected to have a RGE and 572 (89%) patients had presumed gastroparesis. Gastric emptying was found to be normal in 290 (45%), rapid in 182 (28%) and delayed in 170 (27%) patients. Normal, rapid and delayed gastric emptying were seen, respectively, in 17 (24%), 48 (69%) and five (7%) patients with the clinical suspicion of dumping and 273 (48%), 134 (23%) and 165 (29%) patients with suspected gastroparesis. The positive predictive value of clinical suspicion for RGE was 62%, whereas the positive predictive value of delayed gastric emptying was 29%. Of the 182 patients with RGE, 144 (79%) were found to have no obvious explanation for this result; reactive hypoglycaemia was present in a quarter of these patients, but diarrhoea was seen only in 3%. CONCLUSION: Upper gastrointestinal symptoms have a poor clinical specificity to the actual rate of gastric emptying on scintigraphy. Diarrhoea as a symptom does not appear to be associated frequently with RGE, but our results confirm its relationship with hypoglycaemia. The majority of patients with a rapid emptying on gastric-emptying scintigraphy have no identifiable cause for an accelerated motility. Scintigraphic gastric-emptying studies provide a reliable and noninvasive method of investigation in patients where conventional investigations have failed to establish the cause of upper gastrointestinal dysfunction.

Post-prandial reactive hypoglycaemia and diarrhea caused by idiopathic accelerated gastric emptying: a case report.

INTRODUCTION: The majority of cases of post-prandial reactive hypoglycemia are considered idiopathic. Abnormalities of B-cell function and glucose regulation by insulin and glucagon have been postulated as causes but associated gastrointestinal dysfunction has not been reported. We report the first case of accelerated gastric emptying associated with post-prandial reactive hypoglycemia, abdominal bloating and diarrhea. We consider that gastric dysmotility is an important cause of this condition as treatment of the underlying abnormal gastric emptying allows effective control of symptoms. CASE PRESENTATION: A 20-year-old Caucasian woman presented with post-prandial fatigue, sweating, nausea, faintness and intermittent confusion, which had led to pre-syncope and syncope on occasions. She also experienced marked abdominal bloating and diarrhea over the same period. These episodes responded to oral administration of sweet drinks. Her symptoms were ameliorated by modification of her diet. CONCLUSION: This is an original case report of the association of idiopathic accelerated gastric emptying with post-prandial reactive hypoglycemia and diarrhea. Family physicians, endocrinologists and gastroenterologists often consult patients with a constellation of post-prandial symptoms, which are considered to be idiopathic in most cases. This case indicates that gastric dysmotility might be the primary cause of these symptoms in some patients and, if found, offers a therapeutic target which in our case was successful.

Chronic social stress impairs thermal tolerance in the rainbow trout (Oncorhynchus mykiss).

When faced with limited resources, juvenile salmonid fish form dominance hierarchies that result in social stress for socially subordinate individuals. Social stress, in turn, can have consequences for the ability of the fish to respond to additional stressors such as pathogens or exposure to pollutants. In the present study, the possibility that social stress affects the ability of rainbow trout (Oncorhynchus mykiss) to tolerate acute increases in water temperature was investigated. To this end, we first evaluated physiological and cellular stress responses following a 1 h heat shock in juvenile fish in dominance hierarchies. We measured stress hormone (cortisol and catecholamines) concentrations and blood, brain and liver tissue levels of three heat shock proteins (HSPs), the stress inducible HSP70, the constitutive HSC70 and HSP90, in dominant and subordinate trout. No effects of social status on the hormonal response to the heat stress were detected, but the cellular heat shock response in the brain and liver of dominant and subordinate individuals was inhibited. We then assessed thermal tolerance in dominant and subordinate fish through critical thermal maximum temperature (CT(max)) trials and measured HSPs following the heat shock. Subordinate fish were less thermally tolerant than their dominant counterparts. We conclude that social stress impacts the ability of fish to respond, on a cellular scale and in a tissue-specific manner, to increases in water temperature, with likely consequences for overall fitness.

Utility of whole gut transit scintigraphy in patients with chronic gastrointestinal symptoms.

BACKGROUND: To review our experience of doing whole gut transit scintigraphy in patients presenting with functional gastrointestinal problems and to determine its clinical usefulness. METHOD: All whole gut transit studies using a liquid meal over a 5-year-period were reviewed and clinical outcome assessed. RESULTS: Fifty-five patients (44 women; mean age 43 years) underwent whole gut transit scintigraphy using indium-111 diethylene triamine penta-acetic acid in water. The main symptoms were constipation (49%), dyspepsia (25%) and diarrhoea (25%). Colonic transit was delayed in 63% of patients with constipation, which was significantly (P=0.005) higher than that in patients with dyspepsia. Delayed colonic transit was also seen in 43% of patients with diarrhoea. Only 26% of patients with constipation had a delay in liquid gastric emptying and small bowel transit. Gastric emptying, small bowel transit and colonic transit were normal in 43, 79 and 29% of patients with dyspepsia, respectively. There was no statically significant difference in gastric emptying and small bowel transit between patients with constipation, diarrhoea and dyspepsia. CONCLUSION: Liquid-phase whole gut transit scintigraphy seems to be a useful investigation in patients with chronic gastrointestinal symptoms. Rational use of this modality may help the clinician change the management or better characterize the underlying problem/diagnosis in the majority of patients with functional symptoms.

Is intestinal transplantation now an alternative to home parenteral nutrition?

Patients with irreversible intestinal failure and complications of parenteral nutrition should now be routinely considered for small intestine transplantation. Despite attempts for >40 years immunological graft intolerance presented an impenetrable barrier to successful engraftment until the development in the late 1970s of the powerful calcineurin-inhibitor immunosuppressive agents. Their use over the last 17 years has led to small intestinal transplantation being generally considered as a routine option for patients with irreversible intestinal failure and failing parenteral nutrition. The 1-year patient survival rates (%) are now excellent for renal (95), liver (78), heart (82) and lung (75) transplantation. In contrast, survival rates for small intestinal transplantation have been slow to improve, although they are now approaching those for lung and liver transplantation (intestine 78%, intestine and liver 60%, multivisceral 66%), and well-performing centres report recent 1-year graft survival rates as high as 92%. Patient 5-year survival (%) has also improved (intestine alone 50, intestine and liver 50 and multivisceral 62) and compares increasingly favourably with renal (85), liver (67), heart (67) and lung (46). Currently, small intestinal transplantation is reserved for patients with irreversible small intestinal failure who have a poor prognosis on parenteral nutrition. However, as 5-year patient survival following intestinal transplantation approaches that for parenteral nutrition there will be increasing pressure to offer this modality of treatment as an alternative to parenteral nutrition, especially for those patients who have a poor quality of life as a result of parenteral nutrition.

Quantification of disease activity in patients undergoing leucocyte scintigraphy for suspected inflammatory bowel disease.

PURPOSE: Whole-body gamma camera counting is an alternative to faecal 111In collection for quantifying disease activity in inflammatory bowel disease (IBD) but requires administration of imaging activities of 111In. The aim of this study was to explore a dedicated whole-body counter which requires 20-fold less activity than gamma camera counting. METHODS: Thirty patients with known or suspected IBD received 99mTc-granulocytes (approximately 200 MBq) and 111In-granulocytes (approximately 0.5 MBq). The 99mTc-cells were injected 45 min after the 111In-cells and immediately after a baseline 111In whole-body count. The decay-corrected count at 120 h was expressed as a fraction of baseline to give whole-body 111In retention (WBR). One patient was excluded as the injected cells were non-viable. RESULTS: Median 45-min intravascular 111In recovery was 35% in patients compared with 43% in six normal volunteers (p<0.05). WBR in normals ranged from 91% to 93% and in 11 patients with negative 99mTc imaging from 87% to 96%. Only one of 11 patients with negative imaging had WBR <90% while 11/12 patients with WBR <90% had abnormal imaging. Ten of 13 patients with Crohn's disease (CD) had abnormal imaging. The lowest WBR in these ten was 77% and six had values of >90%. There was a significant association between WBR and 99mTc image grade (Rs=0.73, p<0.002) in 16 patients without CD, but not in 13 patients with CD (Rs=0.54, p>0.05). CONCLUSION: Dedicated whole-body counting is able to quantify disease activity in IBD but may give normal values in active CD.

Small-intestinal dysfunction accompanies the complex endocrinopathy of human proprotein convertase 1 deficiency.

We have previously described the only reported case of human proprotein convertase 1 (PC1) deficiency, in a female (Subject A) with obesity, hypogonadism, hypoadrenalism, and reactive hypoglycemia. We now report the second case of human PC1 deficiency (Subject B), also due to compound heterozygosity for novel missense and nonsense mutations. While both subjects shared the phenotypes of obesity, hypoadrenalism, reactive hypoglycemia, and elevated circulating levels of certain prohormones, the clinical presentation of Subject B was dominated by severe refractory neonatal diarrhea, malabsorptive in type. Subsequent investigation of Subject A revealed marked small-intestinal absorptive dysfunction, which was not previously clinically suspected. We postulate that PC1, presumably in the enteroendocrine cells, is essential for the normal absorptive function of the human small intestine. The differences in the nature and severity of presentation between the two cases cannot readily be explained on the basis of allelic heterogeneity, as the nonsense and missense mutations from both subjects had comparably severe effects on the catalytic activity of PC1. Despite Subject A's negligible PC1 activity, some mature ACTH and glucagon-like peptide 17-36(amide) were detectable in her plasma, suggesting that the production of these hormones, at least in humans, does not have an absolute dependence on PC1. The presence of severe obesity and the absence of growth retardation in both subjects contrast markedly with the phenotype of mice lacking PC1 and suggest that the precise physiological repertoire of this enzyme may vary between mammalian species.