A dominant negative heterozygous G87R mutation in the zinc transporter, ZnT-2 (SLC30A2), results in transient neonatal zinc deficiency.

Zinc is an essential mineral, and infants are particularly vulnerable to zinc deficiency as they require large amounts of zinc for their normal growth and development. We have recently described the first loss-of-function mutation (H54R) in the zinc transporter ZnT-2 (SLC30A2) in mothers with infants harboring transient neonatal zinc deficiency (TNZD). Here we identified and characterized a novel heterozygous G87R ZnT-2 mutation in two unrelated Ashkenazi Jewish mothers with infants displaying TNZD. Transient transfection of G87R ZnT-2 resulted in endoplasmic reticulum-Golgi retention, whereas the WT transporter properly localized to intracellular secretory vesicles in HC11 and MCF-7 cells. Consequently, G87R ZnT-2 showed decreased stability compared with WT ZnT-2 as revealed by Western blot analysis. Three-dimensional homology modeling based on the crystal structure of YiiP, a close zinc transporter homologue from Escherichia coli, revealed that the basic arginine residue of the mutant G87R points toward the membrane lipid core, suggesting misfolding and possible loss-of-function. Indeed, functional assays including vesicular zinc accumulation, zinc secretion, and cytoplasmic zinc pool assessment revealed markedly impaired zinc transport in G87R ZnT-2 transfectants. Moreover, co-transfection experiments with both mutant and WT transporters revealed a dominant negative effect of G87R ZnT-2 over the WT ZnT-2; this was associated with mislocalization, decreased stability, and loss of zinc transport activity of the WT ZnT-2 due to homodimerization observed upon immunoprecipitation experiments. These findings establish that inactivating ZnT-2 mutations are an underlying basis of TNZD and provide the first evidence for the dominant inheritance of heterozygous ZnT-2 mutations via negative dominance due to homodimer formation.

Cellular and clinical report of new Griscelli syndrome type III cases.

The RAB27A/Melanophilin/Myosin-5a tripartite protein complex is required for capturing mature melanosomes in the peripheral actin network of melanocytes for subsequent transfer to keratinocytes. Mutations in any one member of this tripartite complex cause three forms of Griscelli syndrome (GS), each with distinct clinical features but with a similar cellular phenotype. To date, only one case of GS type III (GSIII), caused by mutations in the Melanophilin (MLPH) gene, has been reported. Here, we report seven new cases of GSIII in three distinct Arab pedigrees. All affected individuals carried a homozygous missense mutation (c.102C>T; p.R35W), located in the conserved Slp homology domain of MLPH, and had hypomelanosis of the skin and hair. We report the first cellular studies on GSIII melanocytes, which demonstrated that MLPH(R35W) causes perinuclear aggregation of melanosomes in melanocytes, typical for GS. Additionally, co-immunoprecipitation assays showed that MLPH(R35W) lost its interaction with RAB27A, indicating pathogenicity of the R35W mutation.

Idiopathic pancreatitis preceding the diagnosis of inflammatory bowel disease is more frequent in pediatric patients.

BACKGROUND AND OBJECTIVES: Acute pancreatitis (AP) can be a rare extraintestinal manifestation of inflammatory bowel disease (IBD). There are only a few reports of AP presenting before the diagnosis of IBD. We aimed to characterize the demographic, clinical, and laboratory data of patients with IBD in whom AP preceded disease onset and compare the presentation of AP between children and adults. PATIENTS AND METHODS: Pediatric and adult patients presenting with AP as the first symptom of IBD were retrospectively identified (10 years, 7 university hospitals). Demographic and clinical data, IBD type, disease extension, and laboratory data were extracted from the charts. Imaging methods, number of AP episodes, and lag time between onset of first pancreatitis episode and onset of IBD were recorded. RESULTS: AP preceding the diagnosis of IBD was found in 10 in 460 pediatric patients with IBD (2.17%), compared with only 2 in 3500 adults (0.06%). Eight children had colonic disease (4 Crohn disease, 4 ulcerative colitis [3 pancolitis]). Mean amylase level was 1419 and range 100 to 1370. Three children (30%) had mildly elevated transaminases. Median time between onset of first episode of AP in relation to onset of IBD was 24 (range 1-156) weeks. AP most commonly presented with abdominal pain. CONCLUSIONS: IBD presenting as AP was more frequent among the pediatric population with IBD in comparison to adults. It was more common in patients with colitis than in those with ileal disease, suggesting that patients with idiopathic AP should be observed carefully for a possible diagnosis of IBD.

Cystic fibrosis transmembrane conductance regulator ion channel function testing in recurrent acute pancreatitis.

GOALS: To understand the relationship between acute recurrent pancreatitis and cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. BACKGROUND: An emerging number of patients present with a nonclassic phenotype of cystic fibrosis (CF) with partial features or single-organ disease only. The association between the phenotype of recurrent pancreatitis CFTR dysfunction is unclear. METHODS: Patients with idiopathic recurrent pancreatitis were referred for electrophysiologic investigation. RESULTS: Thirty-three patients (18 males) aged 20+/-12 years with recurrent pancreatitis were studied. Three patients had mild asthma and 1 patient had mild ulcerative colitis. There was no family history of CF. All patients had normal imaging of the pancreatic duct by endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography. No patient was pancreatic insufficient. Mean sweat chloride values were 41+/-14 meq/L (range: 18 to 64). Nasal potential difference (NPD) measurement was pathologic in 7 patients. Mean basal potential difference in these 7 patients was -33+/-13 mV and there was an abnormal response to chloride-free and isoproterenol solutions. There was no difference in sweat chloride concentration between the 2 groups. Mutation analysis revealed W1282X/5T, D1152H/5T, and W1282X/- in 3 patients with abnormal NPD and 1 W1282X allele was found in 1 patient with normal NPD. CONCLUSIONS: In this series, 21% of patients with recurrent pancreatitis have abnormalities of CFTR function. Patients presenting with recurrent, "idiopathic" pancreatitis require CFTR function testing.

Peritoneal adhesions and intestinal obstructions in patients with familial Mediterranean fever--are they more frequent?

OBJECTIVE: Familial Mediterranean fever (FMF) is characterized by recurrent episodes of peritonitis. A controversy exists as to whether intestinal obstruction due to peritoneal adhesions is more common among FMF patients compared with healthy controls. The aim of the study was to estimate the rate of spontaneous or postsurgical small-bowel obstruction (SBO) in FMF patients. METHODS: We reviewed the charts of 560 FMF patients followed in our clinic for the occurrence of spontaneous SBO. We also assessed the occurrence of postappendectomy intestinal obstruction among 89 FMF patients compared with 417 individuals without FMF who underwent an appendectomy without other abdominal surgery in the same medical center. RESULTS: Ten of 471 FMF patients (2.1%) developed spontaneous SBO, 8 of whom required laparotomy and adhesiolysis. Six of 89 FMF patients (6.7%) who underwent appendectomy developed SBO. None of the non-FMF patients developed SBO. CONCLUSIONS: Our retrospective study showed that FMF patients are at a higher risk than healthy individuals for developing SBO either spontaneously or as a postsurgical complication. Physicians should be alert to this possible complication when FMF patients arrive at the emergency room.

Sludge ball, pseudolithiasis, cholelithiasis and choledocholithiasis from intrauterine life to 2 years: a 13-year follow-up.

OBJECTIVE: Evaluation and follow-up of infants with cholelithiasis and pseudolithiasis in a pediatric ward. PATIENTS & METHODS: Prospective study from April 1990 to October 2003 identified hospitalized infants younger than 2 years with ultrasonographic findings of cholelithiasis, choledocholithiasis or pseudolithiasis. Associated abnormalities or contributory factors were recorded and patients were followed for from 6 months to 13 years (mean, 4 years). RESULTS: Thirty-four patients were diagnosed between the age of 3 weeks and 24 months. Thirteen (38%) had been treated with third-generation cephalosporins. Other associated factors were dehydration in 10 (29%), urinary tract infection in two (6%) and one each for cholestatic liver disease, total parenteral nutrition, immunoglobulin A deficiency and prematurity. Six infants (17%) had no known risk factor. Six additional patients were diagnosed by antenatal ultrasound. CONCLUSIONS: Cholelithiasis in infants hospitalized for a variety of common pediatric conditions is not rare. Dehydration and treatment with third-generation cephalosporins are important associated factors. The classic risk factors of hemolysis and previous gastrointestinal surgery, were not found in our group. The overall prognosis was good. Pseudolithiasis disappeared in all infants. Of the 21 infants with cholelithiasis, only two developed cholecystitis. In nine infants, spontaneous resolution occurred. In the absence of other clinical or imaging evidence of biliary tract disease, conservative management is advised.

Evidence that Griscelli syndrome with neurological involvement is caused by mutations in RAB27A, not MYO5A.

Griscelli syndrome (GS), a rare autosomal recessive disorder, is characterized by partial albinism, along with immunologic abnormalities or severe neurological impairment or both. Mutations in one of two different genes on chromosome 15q can cause the different subtypes of GS. Most patients with GS display the hemophagocytic syndrome and have mutations in RAB27A, which codes for a small GTPase. Two patients with neurological involvement have mutations in MYO5A, which codes for an actin-based molecular motor. The RAB27A and MYO5A gene products interact with each other and function in vesicle trafficking. We report the molecular basis of GS in a Muslim Arab kindred whose members have extremely variable neurological involvement, along with the hemophagocytic syndrome and immunologic abnormalities. The patients have normal MYO5A genes but exhibit a homozygous 67.5-kb deletion that eliminates RAB27A mRNA and immunocytofluorescence-detectable protein. We also describe the molecular organization of RAB27A and a multiplex polymerase chain reaction assay for the founder deletion in this kindred. Finally, we propose that all patients with GS have RAB27A mutations and immunologic abnormalities that sometimes result in secondary neurological involvement. The two patients described elsewhere who have MYO5A mutations and neurological complications but no immunologic defects may not have GS but instead may have Elejalde syndrome, a condition characterized by mild hypopigmentation and severe, primary neurological abnormalities.