Genetic susceptibility to fibrocalculous pancreatic diabetes in Bangladeshi subjects: a family study

Non-tropical fibrocalculous pancreatic diabetes: case reports and review of recent literature

Background

Fibrocalculous pancreatic diabetes (FCPD), an uncommon form of secondary diabetes, is caused by chronic nonalcoholic calcific pancreatitis and primarily occurs in tropical countries.

Objective

To present our first-hand experiences in the diagnosis and management of FCPD in two patients from a non-tropical location.

Case report

Two male Chinese patients (29 and 32 years old) presented with poor insulin function, negative islet cell and glutamate decarboxylase antibodies, and no spontaneous ketosis or abdominal pain. A careful clinical assessment was made and the results were correlated with laboratory findings. Abdominal ultrasound and computed tomography scans further revealed pancreatic calcification, calculi, and pancreatic duct dilation. Differential diagnosis confirmed FCPD and excluded the potential misdiagnosis of type 2 diabetes mellitus. FCPD in these patients was managed with insulin and symptomatic treatment with close monitoring. At the time of submission of this report, the first patient was stable at his last follow-up, but the second had been re-hospitalized for worsening symptoms.

Conclusion

Early differential diagnosis of FCPD based on clinical examination and biochemical and radiological investigations, in tandem with insulin therapy, can help manage FCPD effectively.

Fibrocalculous pancreatic diabetes (FCPD)

Fibrocalculous pancreatic diabetes (FCPD) is an uncommon form of diabetes that occurs as a result of chronic calcific pancreatitis, in the absence of alcohol abuse. The disease is restricted to tropical regions of the world, and southern India has the highest known prevalence of FCPD. The typical patient with FCPD is a lean adolescent or young adult of either sex, presenting with history of recurrent bouts of abdominal pain and steatorrhea. Demonstration of large, discrete pancreatic calculi by plain radiographs or ultrasonography of the abdomen is diagnostic. While the exact etiology of FCPD is unknown, genetic, nutritional and inflammatory factors have been hypothesized to play a role. Diabetes in FCPD is often brittle and difficult to control; most patients require multiple doses of insulin for control of glycemia. However, in spite of high blood glucose levels, patients rarely develop ketosis. Malabsorption responds to pancreatic enzyme supplementation. Surgical removal of stones is indicated for symptomatic relief of intractable pain. While patients with FCPD develop microvascular complications as frequently as those with type 2 diabetes, macrovascular disease is uncommon. Development of pancreatic malignancy is the most dreaded complication and should be suspected in any patient who complains of weight loss, back pain or jaundice.

Genetic and phenotypic heterogeneity in tropical calcific pancreatitis

Tropical calcific pancreatitis (TCP) is a form of chronic non-alcoholic pancreatitis initially reported in the developing parts of the tropical world. The clinical phenotype of TCP has undergone marked changes since its first description in 1968. The disease is now seen in relatively older people with less severe symptoms. In addition, there are varying reports on the proportion of cases presenting with imaging abnormalities like calcification, ductal dilation, and glandular atrophy. Significant progress has also been made in understanding the etiopathology of TCP. The role of malnutrition and cassava toxicity in its pathogenesis is disproven and few studies have focused on the role of micronutrient deficiency and oxidative stress in the etiopathogenesis of TCP. Emerging evidence support an important role for genetic risk factors in TCP. Several studies have shown that, rather than mutations in trypsinogens, variants in serine protease inhibitor kazal type 1, cathepsin B, chymotrypsin C, cystic fibrosis transmembrane regulator, and carboxypeptidase A1, predict risk of TCP. These studies also provided evidence of mutational heterogeneity between TCP and chronic pancreatitis in Western populations. The current review summarizes recent advances that have implications in the understanding of the pathophysiology and thus, heterogeneity in genotype-phenotype correlations in TCP.

Prevalence of pancreatic diabetes in patients carrying mutations or polymorphisms of the PRSS1 gene in the Han population

OBJECTIVE

This study updated the estimated prevalence of type 3c diabetes damage to the pancreas through different genotypes of PRSS1 and their clinical characteristics in the Han population.

SUBJECTS AND METHODS

Cross-sectional analysis was performed of the most recent (2003-2007) patients with pancreatitis from six hospitals of the Han population in South China (n = 253).

RESULTS

There were 32 patients with pancreatitis carrying a PRSS1 gene abnormality within intron region among 253 cases of pancreatitis, including 27 patients carrying novel single nucleotide polymorphisms, namely, IVS 3 +75 A --> G conversion, and five patients with the mutation IVS3 + 10 T --> G. Among these patients, there were only three cases of patients with diabetes (9.37%). This was lower than the prevalence of abnormalities in the exons of the PRSS1 gene (51.92%): 12 patients with c.361 G --> A, eight patients with c.415 T --> A, and five patients with c.365G --> A. Among them were 12 persons with diabetes, including five requiring insulin to regulate blood sugar. What is more, among the 27 patients carrying PRSS1 gene polymorphism (c.486 C --> T, within the exon 4), there were 15 persons with diabetes symptoms. More than 40% of these patients required insulin to regulate blood sugar.

CONCLUSIONS

An abnormality within the intron region of the PRSS1 gene represents one of the causes of pancreatitis in Chinese patients, but it is not related to pancreatic diabetes. However, the exon abnormality obviously raises the morbidity rate of type 3c diabetes, which relies on insulin.

Genetic aspects of tropical calcific pancreatitis

Tropical calcific pancreatitis (TCP) is a subtype of chronic pancreatitis which is unique to tropical regions. Patients present at young age with recurrent abdominal pain, nutritional deficiencies, and insulin-requiring diabetes. For a long time, the aetiology of this disorder was poorly understood. Several environmental factors, such as malnutrition or the consumption of toxic food components such as cyanogenic glycosides, were proposed as pathogenic factors. In the last decade, a major impact on the understanding of the aetiology of TCP has come from genetic studies on hereditary and idiopathic chronic pancreatitis. Genetic alterations in at least five genetic loci are clearly associated with chronic pancreatitis in the Western world. These include alterations in genes coding for trypsinogens, the most abundant digestive enzymes (PRSS1 and PRSS2), the trypsin inhibitor (SPINK1) and the trypsin-degrading enzyme, chymotrypsinogen C (CTRC). In addition, alterations in the cystic fibrosis (CFTR) gene are associated with idiopathic pancreatitis. TCP clinically resembles non-alcoholic chronic pancreatitis of Western countries, suggesting that similar genetic defects might also be of importance in this disease entity. Indeed, alterations in at least two genes, SPINK1 and CTRC, are strongly associated with TCP. The current review focuses on the recent developments in the understanding of the genetic basis of inherited pancreatitis, with special emphasis on TCP.

Juvenile fibrocalculous pancreatopathy--a patient report

Fibrocalculous pancreatopathy (FCPP) is a secondary form of diabetes mellitus (DM) with obscure etiology. Recently various gene mutations have been reported in patients with FCPP from the Indian subcontinent. Initially termed tropical pancreatic diabetes, FCPP is uncommon and is characterized by pancreatic calcifications. The diagnosis is made in the third decade of life in most patients with the onset of abdominal pain and DM. We report a female child with DM diagnosed at the age of 3 years who had been managed with insulin but was ketosis resistant. The diagnosis of FCPP was made 3 years later. There were no mutations at N34S and P55S in the SPINK1 gene.

Analysis of tumour necrosis factor alpha and interleukin 10 promotor variants in patients with chronic pancreatitis

OBJECTIVE

Cationic trypsinogen gene mutations are strong risk factors of hereditary pancreatitis. However, 20% of subjects with a trypsinogen mutation never get pancreatitis and the cause of this incomplete penetrance is unknown. We investigated the influence of interleukin 10 (IL10) and tumour necrosis factor alpha (TNFalpha) promotor variants on the manifestation of chronic pancreatitis of different underlying causes and in pancreatic cancer.

METHODS

A total of 335 German patients with chronic pancreatitis were investigated. In 157 patients the disease was related to alcohol abuse; the other cases were of non-alcoholic origin. In the latter group, the serine protease inhibitor, Kazal type 1 (SPINK1) mutation N34S was found in 72 patients and the trypsinogen mutations N29I or R122H were present in 60 patients; in the remaining 46 patients no mutation was found. In addition, we studied 208 patients with pancreatic cancer. As controls, 116 healthy blood donors and 25 healthy carriers of the trypsinogen mutations N29I or R122H were investigated. After DNA extraction from blood leucocytes, genotyping for the cytokine polymorphisms was performed by induced heteroduplex generators and/or direct DNA sequencing of the IL10 and TNFalpha promotor regions.

RESULTS

The frequencies of the promotor polymorphisms of IL10-627A, IL10-1117A, TNF-238A and TNF-308A in patients with alcoholic chronic pancreatitis, idiopathic pancreatitis, SPINK1-N34S-associated chronic pancreatitis and pancreatic cancer did not differ significantly from the control group. The variant TNF-238A was two to four times more frequent in index patients with trypsinogen mutations than in all other groups. The analysis of the allelic frequencies of whole families with trypsinogen mutations revealed that all subjects with the TNF-238A variant suffered from chronic pancreatitis, whereas all intrafamilial controls with wild-type TNF were unaffected.

CONCLUSIONS

TNFalpha and IL10 promotor variants are not associated with a manifestation of chronic pancreatitis or pancreatic cancer. The variant TNF-238A, however, might be a relevant risk factor for disease manifestation in families with hereditary pancreatitis.

SPINK1 is a susceptibility gene for fibrocalculous pancreatic diabetes in subjects from the Indian subcontinent

Fibrocalculous pancreatic diabetes (FCPD) is a secondary cause of diabetes due to chronic pancreatitis. Since the N34S variant of the SPINK1 trypsin inhibitor gene has been found to partially account for genetic susceptibility to chronic pancreatitis, we used a family-based and case-control approach in two separate ethnic groups from the Indian subcontinent, to determine whether N34S was associated with susceptibility to FCPD. Clear excess transmission of SPINK1 N34S to the probands with FCPD in 69 Bangladeshi families was observed (P<.0001; 20 transmissions and 2 nontransmissions). In the total study group (Bangladeshi and southern Indian) the N34S variant was present in 33% of 180 subjects with FCPD, 4.4% of 861 nondiabetic subjects (odds ratio 10.8; P<.0001 compared with FCPD), 3.7% of 219 subjects with type 2 diabetes, and 10.6% of 354 subjects with early-onset diabetes (aged <30 years) (P=.02 compared with the ethnically matched control group). These results suggest that the N34S variant of SPINK1 is a susceptibility gene for FCPD in the Indian subcontinent, although, by itself, it is not sufficient to cause disease.