Glycogen Storage Disease Type Ib Research Articles

The Physiopathological Role of the Exchangers Belonging to the SLC37 Family.

The human SLC37 gene family includes four proteins SLC37A1-4, localized in the endoplasmic reticulum (ER) membrane. They have been grouped into the SLC37 family due to their sequence homology to the bacterial organophosphate/phosphate (Pi) antiporter. SLC37A1-3 are the less characterized isoforms. SLC37A1 and SLC37A2 are Pi-linked glucose-6-phosphate (G6P) antiporters, catalyzing both homologous (Pi/Pi) and heterologous (G6P/Pi) exchanges, whereas SLC37A3 transport properties remain to be clarified. Furthermore, SLC37A1 is highly homologous to the bacterial glycerol 3-phosphate permeases, so it is supposed to transport also glycerol-3-phosphate. The physiological role of SLC37A1-3 is yet to be further investigated. SLC37A1 seems to be required for lipid biosynthesis in cancer cell lines, SLC37A2 has been proposed as a vitamin D and a phospho-progesterone receptor target gene, while mutations in the SLC37A3 gene appear to be associated with congenital hyperinsulinism of infancy. SLC37A4, also known as glucose-6-phosphate translocase (G6PT), transports G6P from the cytoplasm into the ER lumen, working in complex with either glucose-6-phosphatase-α (G6Pase-α) or G6Pase-β to hydrolyze intraluminal G6P to Pi and glucose. G6PT and G6Pase-β are ubiquitously expressed, whereas G6Pase-α is specifically expressed in the liver, kidney and intestine. G6PT/G6Pase-α complex activity regulates fasting blood glucose levels, whereas G6PT/G6Pase-β is required for neutrophil functions. G6PT deficiency is responsible for glycogen storage disease type Ib (GSD-Ib), an autosomal recessive disorder associated with both defective metabolic and myeloid phenotypes. Several kinds of mutations have been identified in the SLC37A4 gene, affecting G6PT function. An increased autoimmunity risk for GSD-Ib patients has also been reported, moreover, SLC37A4 seems to be involved in autophagy.

Molecular biology and gene therapy for glycogen storage disease type Ib

Glycogen storage disease type Ib (GSD-Ib) is caused by a deficiency in the ubiquitously expressed glucose-6-phosphate (G6P) transporter (G6PT or SLC37A4). The primary function of G6PT is to translocate G6P from the cytoplasm into the lumen of the endoplasmic reticulum (ER). Inside the ER, G6P is hydrolyzed to glucose and phosphate by either the liver/kidney/intestine-restricted glucose-6-phosphatase-α (G6Pase-α) or the ubiquitously expressed G6Pase-β. A deficiency in G6Pase-α causes GSD type Ia (GSD-Ia) and a deficiency in G6Pase-β causes GSD-I-related syndrome (GSD-Irs). In gluconeogenic organs, functional coupling of G6PT and G6Pase-α is required to maintain interprandial blood glucose homeostasis. In myeloid tissues, functional coupling of G6PT and G6Pase-β is required to maintain neutrophil homeostasis. Accordingly, GSD-Ib is a metabolic and immune disorder, manifesting impaired glucose homeostasis, neutropenia, and neutrophil dysfunction. A G6pt knockout mouse model is being exploited to delineate the pathophysiology of GSD-Ib and develop new clinical treatment options, including gene therapy. The safety and efficacy of several G6PT-expressing recombinant adeno-associated virus pseudotype 2/8 vectors have been examined in murine GSD-Ib. The results demonstrate that the liver-directed gene transfer and expression safely corrects metabolic abnormalities and prevents hepatocellular adenoma (HCA) development. However, a second vector system may be required to correct myeloid and renal dysfunction in GSD-Ib. These findings are paving the way to a safe and efficacious gene therapy for entering clinical trials.

Long-Term Outcomes for G-CSF Treatment of Patients with Glycogen-Storage Disease Type Ib

Background: Glycogen-storage disease 1b (GSD 1b) is characterized by neutropenia, hepatomegaly, hypoglycemia, enterocolitis and recurrent severe infections. For more than 25 years, many GSD 1b patients worldwide have been treated with granulocyte colony-stimulating factor (G-CSF).Methods: The Severe Chronic Neutropenia International Registry (SCNIR) enrolls and prospectively follows GSD 1b patients with both severe (ANC< 0.5 x 109/L) and mild or moderate neutropenia (ANC< 1.5 x 109/L). For this report we analyzed records for 83 patients enrolled through the SCNIR offices in Seattle, Washington and Hannover, Germany.Findings -Clinical outcomes: Overall most patients and parents report very favorable outcomes with increases in neutrophils, reduced infections, reduced symptoms of enterocolitis and improved quality of life.Neutropenia: Because splenomegaly may increase markedly with G-CSF treatment, clinical experience dictates that the G-CSF dose should be carefully monitored to maintain the ANC at 1.0 to 2.0 x 109/L. Summary data for treatment of 83 patients are shown in Table 1.Myeloid malignancies: We assessed the risk of GSD 1b patients developing myeloid malignancies from review of the medical literature and patients prospectively followed through the SCNIR. We identified 1 case of AML prior to availability of G-CSF and 6 cases of AML in G-CSF treated patients, 4 from the cohort followed prospectively by the SCNIR. Table 2 shows detailed data for the 7 patients with GSD1b who have developed AML.Conclusions: In the 83 SCNIR patients followed for a mean (median) of 12.2 (11.0) years there are 4 cases (4/83, 4.8%) of AML, or 1 case/253 years of G-CSF treatment. This is lower than the estimated risk of evolution to AML in the major genetic subgroups of severe congenital neutropenia treated with G-CSF, e.g., harboring ELANE, HAX1, SDS mutations . The numbers of patients in other genetic subgroups, such as G6PC3, JAGN1, TCIRG1, etc. are too small to make any reliable comparison about the risk of developing leukemia. (Skokowa J et al. Nat Rev Dis Primers. 2017 Jun 8. doi: 10.1038/nrdp.2017.32. [Epub ahead of print]). [Display omitted] DisclosuresDale:Amgen: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Editor, Current Opinions in Hematology, Honoraria; Cellerant: Membership on an entity's Board of Directors or advisory committees; Genzyme (now owned by Sanofi-Aventis): Consultancy, Patents & Royalties, Research Funding; Genkyotex: Other: DSMB (work completed 6/2015); Hospira: Consultancy; Prolong: Consultancy; Boheringer-Ingelheim: Consultancy; Coherus: Consultancy; Omeros: Other: DSMB; Shire: Other: Independent Review Board; X4Pharma: Research Funding; Philips: Research Funding; Wolter Kluwer: Other: Editor, Current Opinions in Hematology; WedMD/Medscape: Membership on an entity's Board of Directors or advisory committees; National Institutes of Health: Research Funding; University of Washington: Employment, Research Funding; American College of Physicians: Other: Editor and author; GlaxoSmithKline: Equity Ownership; Johnson&Johnson: Equity Ownership. Weinstein:Vitaflo: Research Funding; Dimension Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Liver-directed gene therapy for murine glycogen storage disease type Ib.

Glycogen storage disease type-Ib (GSD-Ib), deficient in the glucose-6-phosphate transporter (G6PT), is characterized by impaired glucose homeostasis, myeloid dysfunction, and long-term risk of hepatocellular adenoma (HCA). We examined the efficacy of G6PT gene therapy in G6pt-/- mice using recombinant adeno-associated virus (rAAV) vectors, directed by either the G6PC or the G6PT promoter/enhancer. Both vectors corrected hepatic G6PT deficiency in murine GSD-Ib but the G6PC promoter/enhancer was more efficacious. Over a 78-week study, using dose titration of the rAAV vectors, we showed that G6pt-/- mice expressing 3-62% of normal hepatic G6PT activity exhibited a normalized liver phenotype. Two of the 12 mice expressing < 6% of normal hepatic G6PT activity developed HCA. All treated mice were leaner and more sensitive to insulin than wild-type mice. Mice expressing 3-22% of normal hepatic G6PT activity exhibited higher insulin sensitivity than mice expressing 44-62%. The levels of insulin sensitivity correlated with the magnitudes of hepatic carbohydrate response element binding protein signaling activation. In summary, we established the threshold of hepatic G6PT activity required to prevent tumor formation and showed that mice expressing 3-62% of normal hepatic G6PT activity maintained glucose homeostasis and were protected against age-related obesity and insulin resistance.

Partial correction of neutrophil dysfunction by oral galactose therapy in glycogen storage disease type Ib

Glycogen storage disease type Ib (GSD-Ib) is characterized by impaired glucose homeostasis, neutropenia and neutrophil dysfunction.Mass spectrometric glycomic profiling of GSD-Ib neutrophils showed severely truncated N-glycans, lacking galactose. Experiments indicated the hypoglycosylation of the electron transporting subunit of NADPH oxidase, which is crucial for the defense against bacterial infections. In phosphoglucomutase 1 (PGM1) deficiency, an inherited disorder with an enzymatic defect just one metabolic step ahead, hypogalactosylation can be successfully treated by dietary galactose. We hypothesized the same pathomechanism in GSD-Ib and started a therapeutic trial with oral galactose and uridine. The aim was to improve neutrophil dysfunction through the correction of hypoglycosylation in neutrophils. The GSD-Ib patient was treated for 29weeks. Monitoring included glycomics analysis of the patient's neutrophils and neutrophil function tests including respiratory burst activity, phagocytosis and migration. Although no substantial restoration of neutrophil glycosylation was found, there was partial improvement of respiratory burst activity.

Glycogen storage disease type Ib neutrophils exhibit impaired cell adhesion and migration

Glycogen storage disease type Ib (GSD-Ib), characterized by impaired glucose homeostasis, neutropenia, and neutrophil dysfunction, is an inherited autosomal recessive disorder caused by a deficiency in the glucose-6-phosphate transporter (G6PT). Neutrophils play an essential role in the defense against invading pathogens. The recruitment of neutrophils towards the inflammation sites in response to inflammatory stimuli is a tightly regulated process involving rolling, adhesion, and transmigration. In this study, we investigated the role of G6PT in neutrophil adhesion and migration using in vivo and in vitro models. We showed that the GSD-Ib (G6pt−/−) mice manifested severe neutropenia in both blood and bone marrow, and treating G6pt−/− mice with granulocyte colony-stimulating factor (G-CSF) corrected neutropenia. However, upon thioglycolate challenge, neutrophils from both untreated and G-CSF-treated G6pt−/−mice exhibited decreased ability to migrate to the peritoneal cavity. In vitro migration and cell adhesion of G6PT-deficient neutrophils were also significantly impaired. Defects in cell migration were not due to enhanced apoptosis or altered fMLP receptor expression. Remarkably, the expression of the β2 integrins CD11a and CD11b, which are critical for cell adhesion, was greatly decreased in G6PT-deficient neutrophils. This study suggests that deficiencies in G6PT cause impairment in neutrophil adhesion and migration via aberrant expression of β2 integrins, and our finding should facilitate the development of novel therapies for GSD-Ib.

Aberrant expression of CD11b and CD11a underlies impaired neutrophil adhesion in glucose-6-phosphate transporter-deficient mice

Abstract Neutrophils play an essential role in defense against intruding microorganisms. They are produced in great number in the bone marrow and circulate in blood where they are found in a quiescent state. In response to inflammatory stimuli, neutrophils take different steps-rolling, adhesion, and transmigration-to migrate towards inflammation sites. In this study, we investigated the underlying mechanisms of impaired neutrophil adhesion in glycogen storage disease type Ib (GSD-Ib) which is caused by a deficiency of the glucose-6-phosphate transporter (G6PT). GSD-Ib is characterized not only by disrupted glucose homeostasis but also by neutropenia and neutrophil dysfunction. GSD-Ib mice were infused with a recombinant adeno-associated virus (rAAV) vector expressing human G6PT only in liver to increase their survival. Unlike control mice, GSD-Ib-rAAV mice manifested severe neutropenia in both blood and bone marrow and neutrophils of GSD-Ib-rAAV mice were defective in adhesion to tumor necrosis factor-a-treated epithelial cells and intercellular adhesion molecule 1 and fibrinogen. The β2-integrins including CD11a/CD18 and CD11b/CD18 are recognized as vital players in neutrophil recruitment. Consistent with impaired neutrophil adhesion, the expression of CD11a and CD11b were found to be decreased in neutrophils of GSD-Ib-rAAV mice, compared with that of control mice. Particularly neutrophils of GSD-Ib-rAAV mice showed increased proteolytic degradation of CD11b. Given the central role of β2-integrins in neutrophil adhesion, this alternation of CD11a and CD11b molecules and their effect on neutrophil adhesion probably define a molecular mechanism to neutrophil dysfunction manifested in GSD-Ib.

165. Liver-Directed Gene Therapy for Murine Glycogen Storage Disease Type IB

Glycogen storage disease type Ib (GSD-Ib) deficient in the glucose-6-phosphate transporter (G6PT or SLC37A4) is characterized impaired glucose homeostasis, myeloid dysfunction, and long-term complication of hepatocellular adenoma (HCA). We have shown that gene therapy mediated by a recombinant (r) AAV8 vector expressing G6PT directed by the chicken β-actin promoter/CMV enhancer enabled the G6pt-/- mice lived to over 51 weeks but all 5 transduced G6pt-/- mice expressed only low levels of hepatic G6PT activity and two developed multiple HCAs with one undergoing malignant transformation. We now examined the safety and efficacy of rAAV8-GPE-G6PT, a rAAV8 vector expressing G6PT directed by the gluconeogenic tissue-specific human G6PC promoter/enhancer (GPE). Of the fifteen rAAV8-GPE-G6PT-treated G6pt-/- mice that lived over age 60 weeks expressed 2-62% of wild-type hepatic G6PT activity with only one developed HCA. The treated mice, including the HCA-bearing mouse exhibit a leaner phenotype along with normal blood metabolite, display normal glucose tolerance profiles, maintain normoglycemia over a 24-hour fast, and retain insulin sensitivity. We further show that activation of hepatic ChREBP signaling that improves glucose tolerance and insulin sensitivity is one mechanism that protects the rAAV-GPE-G6PT-treated G6pt-/- mice against age-related obesity and insulin resistance.

Glycogen storage disease type Ia (GSDIa) but not Glycogen storage disease type Ib (GSDIb) is associated to an increased risk of metabolic syndrome: possible role of microsomal glucose 6-phosphate accumulation.

BackgroundIn GSDIa, glucose 6-phosphate (G6P) accumulates in the endoplasmic reticulum (ER); in GSDIb, G6P levels are reduced in ER. G6P availability directly modulates the activity of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), an ER-bound enzyme playing a key role in the development of the metabolic syndrome (MS).ObjectiveTo evaluate the prevalence of MS and Insulin Resistance (IR) in GSDIa and GSDIb patients.Patients and MethodsThis was a prospective study. All the enrolled patients were followed at the Department of Pediatrics “Federico II” University of Naples for 10 years. Clinical and biochemical parameters of MS and the presence of IR were recorded. The results were correlated with the biochemical parameters of GSDI-related metabolic control. 10 GSDIa patient (median age 12.10 ± 1.50), 7 GSDIb patients (median age 14.90 ± 2.20 were enrolled in the study. They were compared to 20 and 14 age and sex matched controls, respectively. 10 GSDIa patients (median age 24.60 ± 1.50) and 6 GSDIb patients (median age 25.10 ± 2.00) completed the 10-year-follow-up. At the end of the study the patients’ data were compared to 10 and 6 age and sex matched controls, respectively.ResultsAt study entry, 20 % GSDIa patients had MS and 80 % showed 2 criteria for MS. GSDIa patients showed higher HOMA-IR than controls and GSDIb patients (p < 0.001, p < 0.05), respectively. Baseline ISI was lower in GSDIa than controls (p < 0.001). QUICKI was significantly lower in GSDIa than in controls (p < 0.001). At the end of the study 70 % of GSDIa patients had MS and 30 % showed 2 criteria for MS. HOMA-IR was higher in GSDIa than controls (p < 0.01). Baseline ISI was higher in GSDIb than controls (p < 0.005) and GSD1a (p < 0.05). QUICKI was lower in GSD1a patients than in controls (p < 0.03). VAI was higher in GSDIa patients than controls (p < 0.001) and GSDIb patients (p = 0.002).ConclusionsOur data showed high prevalence of IR and MS in GSDIa patients. We speculate a possible role of 11βHSD1 modulation by G6P availability. We suggest a routine metabolic assessment in GSDIa patients.

376. Correction of Metabolic Abnormalities in Murine Glycogen Storage Disease Type Ib by Gene Therapy

Glycogen storage disease type Ib (GSD-Ib) is an autosomal recessive disorder caused by deficiencies in a glucose-6-phosphate (G6P) transporter (G6PT) that transloacates G6P from the cytoplasm into the lumen of the endoplasmic reticulum where it is hydrolyzed to glucose and phosphate by the glucose-6-phosphatase-α (G6Pase-α or G6PC) enzyme. The functional coupling of G6PT and G6Pase-α maintains interprandial blood glucose homeostasis. GSD-Ib patients manifest impaired glucose homeostasis characterized by fasting hypoglycemia, hepatomegaly, nephromegaly, hyperlipidemia, hyperuricemia, lactic acidemia, and growth retardation. The current dietary therapies enable patients to maintain normoglycemia but the underlying pathological processes remain uncorrected and long-term complications, including hepatocellular adenoma (HCA), are common. In this study, we examined the efficacy of liver G6PT delivery mediated by two human G6PT-expressing recombinant adeno-associated virus (AAV) pseudotype 2/8 (rAAV8) vectors. One is a single-stranded vector containing a 2864-bp of the human G6PC promoter/enhancer (rAAV8-GPE-G6PT) and the other is a double-stranded vector containing the minimal human G6PT promoter/enhancer (rAAV8-miGT-G6PT). GSD-Ib mice were infused with either vector neonatally, then at age 4 weeks, and metabolic profiles of the infused animals were monitored at age 12 weeks. We show that the rAAV8-GPE-G6PT vector directed significantly higher levels of hepatic G6PT expression, achieved greater reduction in hepatomegaly, and led to a better toleration of fasting in GSD-Ib mice than the rAAV8-miGT-G6PT vector. Our results suggest that the rAAV8-GPE-G6PT vector is an efficacious vector in correcting metabolic abnormalities in murine GSD-Ib.

Vitamin E Improves Clinical Outcome of Patients Affected by Glycogen Storage Disease Type Ib.

It has been suggested, on a few GSD1b patients, that vitamin E improves neutrophil count and reduces frequency and severity of infections.The main objective of the present study was to investigate the efficacy of vitamin E on the neutropenia, neutrophil dysfunction and IBD in the entire Italian caseload of GSD1b patients. Eighteen GSD1b patients, median age at the time of the study protocol 14.5 (range, 0.6-42 years), were enrolled from four Italian referral centres for metabolic diseases. For the evaluation of the efficacy of vitamin E, neutrophil count and function, frequency of infections needing hospitalization and inflammatory bowel activity were evaluated periodically all over one year before and during vitamin E therapy. Frequency (1.5 ± 0.1 vs. 6.0 ± 0.6, p = 0.003) and severity of infections (2.2 ± 0.2 vs. 3.7 ± 0.4, p = 0.003) were lower and mean value of neutrophil count (1,583 ± 668 vs. 941 ± 809, p = 0.03) higher during vitamin E supplementation. Neutrophil function results improved during vitamin supplementation. PCDAI showed a significant reduction in the inflammatory activity during vitamin E supplementation (9 ± 1.4 vs. 13 ± 1.2, p = 0.006). In seven patients G-CSF requirement decreased and the dose was reduced after the end of the study.In conclusion, our study demonstrated the efficacy of vitamin E supplementation. Vitamin E has evident advantages as compared to G-CSF, as it can be assumed orally, and it has not been associated with severe side effects.

High Incidence of Serologic Markers of Inflammatory Bowel Disease in Asymptomatic Patients with Glycogen Storage Disease Type Ia.

Most patients with glycogen storage disease (GSD) type Ib show features related to inflammatory bowel disease (IBD). The development of IBD seems to be associated with the defect of neutrophil function in GSD Ib. Patients with GSD Ia were not recognized to have similar gastrointestinal complaints until recently and are not associated with a neutrophil defect. Fifty consecutive GSD Ia inpatients over the age of 2 years without a diagnosis of IBD were screened using serologic and genetic markers via the Prometheus IBD sgi Diagnostic test. Eleven patients were tested positive for IBD (22%), with five fitting the pattern for Crohn's disease, five for ulcerative colitis, and one with nonspecific IBD. Only 2 out of the 11 patients had any gastrointestinal complaints. No pattern could be distinguished from individual inflammatory markers, genetics, inflammation antibodies, age, complications, or metabolic control. Of note, 9 out of 11 patients testing positive were female. Patients with GSD Ia were found to have a higher rate of serologically indicated IBD when compared with the general population. While these subjects will need to be followed to determine if these serologic markers correlate with clinical disease, this study supports that IBD may be more common in the GSD Ia population. Further studies are warranted to explain the relationship between IBD and GSD I since it may provide clues regarding the pathogenesis of IBD development in the general population.

Ischemic stroke in left ventricular noncompaction and celiac disease

Left ventricular hypertrabeculation/noncompaction (LVHT) is a cardiac abnormality characterized by a hypertrabeculated left ventricular wall with a sponge-like appearance and a two-layered structure with an outer, subepicardially located compacted zone and an inner, subendocardially located noncompacted zone. Cardiac manifestations of LVHT comprise heart failure, thromboembolism and arrhythmias. LVHT is frequently associated with extracardiac diseases and neuromuscular disorders [1,2]. LVHT associated with digestive disorders, so far, has been only reported in a boy with glycogen storage disease type Ib [3].

Molecular mechanisms of neutrophil dysfunction in glycogen storage disease type Ib

AbstractGlycogen storage disease type Ib (GSD-Ib) is an autosomal-recessive syndrome characterized by neutropenia and impaired glucose homeostasis resulting from a deficiency in the glucose-6-phosphate (G6P) transporter (G6PT). The underlying cause of GSD-Ib neutropenia is an enhanced neutrophil apoptosis, but patients also manifest neutrophil dysfunction of unknown etiology. Previously, we showed G6PT interacts with the enzyme glucose-6-phosphatase-β (G6Pase-β) to regulate the availability of G6P/glucose in neutrophils. A deficiency in G6Pase-β activity in neutrophils impairs both their energy homeostasis and function. We now show that G6PT-deficient neutrophils from GSD-Ib patients are similarly impaired. Their energy impairment is characterized by decreased glucose uptake and reduced levels of intracellular G6P, lactate, adenosine triphosphate, and reduced NAD phosphate, whereas functional impairment is reflected in reduced neutrophil respiratory burst, chemotaxis, and calcium mobilization. We further show that the mechanism of neutrophil dysfunction in GSD-Ib arises from activation of the hypoxia-inducible factor-1α/peroxisome-proliferators–activated receptor-γ pathway.

G6PT Inhibition Model Using HL-60 Cells and Induction of ROS Production through PKC/NOX2 Activation: Clinical Condition for Elucidation of Glycogen Storage Disease Type Ib

G6PT Inhibition Model Using HL-60 Cells and Induction of ROS Production through PKC/NOX2 Activation: Clinical Condition for Elucidation of Glycogen Storage Disease Type Ib

Chapter Ten - The SLC37 Family of Sugar-Phosphate/Phosphate Exchangers

The SLC37 family members are endoplasmic reticulum (ER)-associated sugar-phosphate/phosphate (P(i)) exchangers. Three of the four members, SLC37A1, SLC37A2, and SLC37A4, function as Pi-linked glucose-6-phosphate (G6P) antiporters catalyzing G6P:P(i) and P(i):P(i) exchanges. The activity of SLC37A3 is unknown. SLC37A4, better known as the G6P transporter (G6PT), has been extensively characterized, functionally and structurally, and is the best characterized family member. G6PT contains 10 transmembrane helices with both N and C termini facing the cytoplasm. The primary in vivo function of the G6PT protein is to translocate G6P from the cytoplasm into the ER lumen where it couples with either the liver/kidney/intestine-restricted glucose-6-phosphatase-α (G6Pase-α or G6PC) or the ubiquitously expressed G6Pase-β (or G6PC3) to hydrolyze G6P to glucose and P(i). The G6PT/G6Pase-α complex maintains interprandial glucose homeostasis, and the G6PT/G6Pase-β complex maintains neutrophil energy homeostasis and functionality. G6PT is highly selective for G6P and is competitively inhibited by cholorogenic acid and its derivatives. Neither SLC37A1 nor SLC37A2 can couple functionally with G6Pase-α or G6Pase-β, and the antiporter activities of SLC37A1 or SLC37A2 are not inhibited by cholorogenic acid. Deficiencies in G6PT cause glycogen storage disease type Ib (GSD-Ib), a metabolic and immune disorder. To date, 91 separate SLC37A4 mutations, including 39 missense mutations, have been identified in GSD-Ib patients. Characterization of missense mutations has yielded valuable information on functionally important residues in the G6PT protein. The biological roles of the other SLC37 proteins remain to be determined and deficiencies have not yet been correlated to diseases.

P-001 Crohn’s-like Disease in a Patient with Good Syndrome

There has been described a Crohn’s-like disease in patients with congenital immunodeficiency syndromes (chronic granulomatous disease, glycogen storage disease type Ib, common variable immunodeficiency…). We report a case of a Crohn’s-like colitis and perianal fistula in a patient with Good Syndrome, an acquired immunodeficiency. A 58 years old male, was diagnosed in January 2004 of thymoma and secondary hypogammaglobulinemia (Good Syndrome). He was treated by thymectomy and radiotherapy. Eleven months later the surgery, the patient developed bloody diarrhea, colicky abdominal pain, fever, weight loss and complex perianal fistula. In physical exam, abdomen exploration was not remarkable; there was a perianal fistula with fecal and purulent drainage. The laboratory findings were: hemoglobin 12.4 g/dL, platelets 70 × 10^9, CD4 293 cells/μL, CD3 and CD8 were normal, ratio CD4/CD8 0.34, IgA 14 mg/dL and IgM 5 mg/dL. The rest of results were normal. A colonoscopy was carried out finding multiple superficial ulcers in rectum, sigma, left colon and cecum. Transverse, right colon and ileum were unaffected. Biopsies showed nonspecific moderate inflammatory infiltrate of lymphocytes and plasma cells. No granulomas, crypt abscesses or CMV inclusions were found. Fecal cultures were all negative. Finally a probability diagnosis of Crohn’s disease was done and the patient was treated with mesalazine, steroids and metronidazole without any improvement. Monthly IV immunoglobulins were also administered. Thiopurines and anti-TNF were not used because of recent diagnosis of thymoma. During the following 5 years progressive pancytopenia was developed and recurrent fungal, bacterial and viral infections occurred including a septic shock. Finally the patient died in February 2009 because of E. coli septicemia. Thymomas represent 0.2%–1.5% of malignant neoplasias; 3%–6% of them develop hypogammaglobulinemia after the surgery, what it is called Good syndrome. This acquired immunodeficiency is both cellular and humoral; Immunoglobulins are absent or very low and CD4 are low with a CD4/CD8 ratio <1. The patient suffers different recurrent and opportunistic infections; being the general survival 4 years. There is no specific treatment despite IV immunoglobulins therapy. A Crohn’s-like disease has been reported in other immunodeficiency syndromes (as a chronic granulomatous disease, glycogen storage disease type Ib or common variable immunodeficiency). Our patient had a phenotypically Crohn’s disease pattern, but biopsy was not specific and he did not have a response after steroids treatment. We hypothesize that this patient had a Crohn’s-like syndrome similar to those have been reported in other immunodeficiencies. Congenital immunodeficiency syndromes sometimes developed a Crohn’s-like syndrome. - Good syndrome is an acquired immunodeficiency syndrome compromising both cellular and humoral immune response. - We describe a Crohn’s-like syndrome on a patient with Good syndrome, suggesting a similar pathogenic mechanism with congenital immunodeficiency and possibly Crohn’s disease.

Establishment and directed differentiation of induced pluripotent stem cells from glycogen storage disease type Ib patient

Glycogen storage disease type Ib (GSDIb) is caused by a deficiency in the glucose-6-phosphate transporter (G6PT), which leads to neutrophil dysfunction. However, the underlying causes of these dysfunctions and their relationship with glucose homeostasis are unclear. Induced pluripotent stem cells (iPSCs) hold a great promise for advances in developmental biology, cell-based therapy and modeling of human disease. Here, we examined the use of iPSCs as a model for GSDIb. In this study, one 2-year-old patient was genetically screened and diagnosed with GSDIb. We established iPSCs and differentiated these cells into hepatocytes and neutrophils, which comprise the main pathological components of GSDIb. Cells that differentiated into hepatocytes exhibited characteristic albumin secretion and indocyanine green uptake. Moreover, iPSC-derived cells generated from patients with GSDIb metabolic abnormalities recapitulated key pathological features of the diseases affecting the patients from whom they were derived, such as glycogen, lactate, pyruvate and lipid accumulation. Cells that were differentiated into neutrophils also showed the GSDIb pathology. In addition to the expression of neutrophil markers, we showed increased superoxide anion production, increased annexin V binding and activation of caspase-3 and caspase-9, consistent with the GSDIb patient's neutrophils. These results indicate valuable tools for the analysis of this pathology and the development of future treatments.

SCT for Secondary AML in a Patient with Glycogen Storage Disease Type 1b

AbstractAbstract 4402It is well established that patients with congenital neutropenia due to mutations of ELANE or HAX1 have a strongly increased risk of developing secondary leukemia. In contrast, the leukemia risk is not strongly increased in patients with specific other neutropenia subtypes (e. g. cyclic neutropenia with ELANE mutations). Here we report the first glycogen storage disease type Ib (GSD1b) patient in our registry who developed acute myelogenous leukemia (AML). GSD1b is an autosomal recessive disorder of glycogen metabolism with intracellular accumulation of glycogen caused by mutations in the glucose-6-phosphate translocase gene. Patients present with hepatomegaly, growth retardation, hypoglycemia, lactic acidosis as well as neutropenia and neutrophil dysfunction predisposing to bacterial infections. G-CSF has been shown to be an effective long-term treatment for GSD1b patients leading to an increase in neutrophil counts and enhancement of neutrophil function resulting in fewer infections and improved quality of life. The European Branch of the Severe Chronic Neutropenia International Registry (SCNIR) has collected long-term data from 23 patients with GSD1b. Median age was 17 years, 3 patients expired from infections at an age of 8; 9 and 26 years, respectively. All 23 patients received G-CSF treatment for a median duration of 9.5 years, 22 patients received continuous G-CSF with a median dose of 3.4 mcg/kg/day (range 0.8 to 5 mcg/kg/day), one patient received G-CSF interventionally only.Our patient was diagnosed with AML FAB classification M2 linked to cytogenetic aberrations involving trisomy 21. Leukemia cells also harboured a missense RUNX 1 mutation in exon 3. G-CSF treatment was initiated at age 5 months at a dose of 2.3 mcg/kg/d and was continued until AML diagnosis at age 10 years. The G-CSF dose was increased due to low ANCs and infectious episodes with otitis media and pneumonitis up to 4.05 mcg/kg/day. After initial AML treatment with a hypometylating chemotherapy consisting of azacytidine and cytarabine she developed partially reversible renal insufficiency and oxygen dependent pneumonitis which led to a reduction of chemotherapy despite persistence of AML blasts.Remission was achieved with the use of mylotarg. Subsequently, she received a conditioning regimen with melphalan, fludarabine and treosulfan plus ATG-Fresenius followed by infusion of 10/10 HLA matched peripheral blood stem cells from an unrelated donor. Leukocyte engraftment occurred on day +18 followed by neutrophil engraftment on day +21. Post-SCT she developed grade III skin GvHD on day +8 which was responsible to steroid treatment. Discussion:Up to date 3 GSD1b patients with development of AML have been reported in the literature. Two patients were on long-term G-CSF treatment (Pinsk et al. J Pediatr. 2002; Schroeder et al. J Medical Case Reports 2008), one patient transformed predating the availability of G-CSF (Simmons et al. J Pediatr. 1984). Conclusion:According to the literature, leukemic transformation in patients with GSD1b is a rare event. However, with a total of four patients reported with secondary AML with or without G-CSF treatment, GSD1b patients may have a higher leukemia risk than previously anticipated. Independent from G-CSF treatment, regular bone marrow examinations (morphology, cytogenetics, mutation analysis of candidate genes such as RUNX1) may help to detect malignant transformation early and therefore avoid chemotherapy prior to SCT. SCT is a treatment option for AML in GSD1b, but further data is required. Disclosures:No relevant conflicts of interest to declare.

Noncompaction myocardium in association with type Ib glycogen storage disease

Noncompaction myocardium is a rare disorder assumed to occur as an arrest of the compaction process during the normal development of the heart. Left ventricular noncompaction has been reported to be associated with a variety of cardiac and extracardiac, especially neuromuscular abnormalities. Moreover, it has been suggested that metabolic alterations could be responsible for the noncompaction. However, no association of noncompaction myocardium with type Ib glycogen storage disease (GSD) has been reported so far. Type Ib GSD is due to a defect of a transmembrane protein which results, similar to type Ia GSD, in hypoglycemia, a markedly enlarged liver and, additionally, in neutropenia, recurrent infections, and inflammatory bowel disease. Until now, no muscular or cardiac involvement has been described in type Ib GSD patients. The present case represents the first report of a noncompaction myocardium in a child with type Ib GSD who died of sudden clinical deterioration at the age of four.