title: Genotype/phenotype correlation in glycogen storage disease type 1b: a multicentre study and review of the literature.
abstract: We studied the genotype/phenotype correlation in a cohort of glycogen storage disease type (GSD) 1b patients. A total of 25 GSD1b patients, 13 females and 12 males, age range: 4.3-28.4 years, mean:14.6+/-6.8 years; median: 15 years, representing the entire case load of Italian GSD1b patients, were enrolled in the study. Molecular analysis of the glucose 6-phosphate translocase (G6PT1) gene was performed in all patients. We analysed the presence of a correlation among both the clinical features associated with GSD1b (neutropenia, frequency of admission to the hospital for severe infections) and the presence of systemic complications (liver adenomas, nephropathy, bone mineral density defect, polycystic ovaries, short stature, inflammatory bowel disease) and the mutations detected in each patient. Nine patients were homozygous or compound heterozygous for mutations causing stop codons. In particular, three patients were homozygous for the same mutation (400X); of these patients, one showed chronic neutropenia with severe and frequent infections and severe inflammatory bowel disease, another patient cyclic neutropenia associated with rare bacterial infections and mild bowel involvement and the last one normal neutrophil count. Two patients were homozygous for the mutation 128X; one of these patients did not show neutropenia, whereas the other one had severe neutropenia needing frequent hospital admission and was under granulocyte-colony stimulating factor treatment. In three patients no mutations were detected.
  
  
  CONCLUSIONS
  No correlation was found between individual mutations and the presence of neutropenia, bacterial infections and systemic complications. These results suggest that different genes and proteins modulate neutrophil differentiation, maturation and apoptosis and thus the severity and frequency of infections. The absence of detectable mutations in three patients could suggest that a second protein plays a role in microsomal phosphate transport.
authors.affiliation: Dipartimento di Pediatria, Università Federico II, Via Sergio Pansini 5, 80131 Napoli, Italy. danlis@tin.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Melis
authors.forename: Rossella
authors.initials: R
authors.lastname: Fulceri
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Parenti
authors.forename: Paola
authors.initials: P
authors.lastname: Marcolongo
authors.forename: Rosanna
authors.initials: R
authors.lastname: Gatti
authors.forename: Rossella
authors.initials: R
authors.lastname: Parini
authors.forename: Enrica
authors.initials: E
authors.lastname: Riva
authors.forename: Roberto
authors.initials: R
authors.lastname: Della Casa
authors.forename: Enrico
authors.initials: E
authors.lastname: Zammarchi
authors.forename: Generoso
authors.initials: G
authors.lastname: Andria
authors.forename: Angelo
authors.initials: A
authors.lastname: Benedetti
mesh_terms: D000293:Adolescent; D000328:Adult; D017920:Antiporters / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D005838:Genotype; D005953:Glycogen Storage Disease Type I / Q000150:complications* / Q000235:genetics*; D006801:Humans; D007558:Italy; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009154:Mutation; D009503:Neutropenia / Q000235:genetics / Q000628:therapy; D010641:Phenotype
chemical_list: D017920:Antiporters; D009004:Monosaccharide Transport Proteins; C503531:SLC37A4 protein, human