Glycogen Storage Disease Iii

A number sign (#) is used with this entry because glycogen storage disease III (GSD3) is caused by homozygous or compound heterozygous mutation in the AGL gene (610860), which encodes the glycogen debrancher enzyme, on chromosome 1p21.

Description

Glycogen storage disease III is an autosomal recessive metabolic disorder caused by deficiency of the glycogen debrancher enzyme and associated with an accumulation of abnormal glycogen with short outer chains. Most patients are enzyme-deficient in both liver and muscle (IIIa), but about 15% are enzyme-deficient in liver only (IIIb) (Shen et al., 1996). These subtypes have been explained by differences in tissue expression of the deficient enzyme (Endo et al., 2006). In rare cases, selective loss of only 1 of the 2 debranching activities, glucosidase or transferase, results in type IIIc or IIId, respectively. (Van Hoof and Hers, 1967; Ding et al., 1990).

Clinically, patients with GSD III present in infancy or early childhood with hepatomegaly, hypoglycemia, and growth retardation. Muscle weakness in those with IIIa is minimal in childhood but can become more severe in adults; some patients develop cardiomyopathy (Shen et al., 1996).

Lucchiari et al. (2007) provided a review of GSD III.

Clinical Features

Brunberg et al. (1971) reported an adult with GSD III who had diffuse muscle weakness and wasting. DiMauro et al. (1979) reported 5 adult patients with adult-onset, slowly progressive muscle weakness associated with debrancher enzyme deficiency. Two patients had distal muscle wasting, 3 had hepatomegaly, and 2 had congestive heart failure. Electromyography showed a mixed pattern with abundant fibrillations, and serum creatine kinase was increased 5- to 45-fold. Skeletal muscle biopsy showed a vacuolar myopathy with increased glycogen content. DiMauro et al. (1979) suggested that debrancher deficiency myopathy may not be rare and should be considered in the differential diagnosis of adult-onset hereditary myopathies.

Fellows et al. (1983) reported 2 unrelated adults with GSD III who presented with liver disease, one of whom developed fatal cirrhosis. Both had hepatomegaly since childhood. Histology showed unusual hepatic vacuolation.

In Israel, Moses et al. (1989) performed cardiologic studies on 20 patients, aged 3 to 30 years, with enzymatically proven GSD IIIa. Seventeen patients showed subclinical evidence of cardiac involvement in the form of ventricular hypertrophy on ECG; 13 of 16 patients in whom an echocardiographic examination was performed had abnormal findings. Only 2 had cardiomegaly on x-ray. Moses et al. (1989) described in detail the findings in a 25-year-old female with clinically evident cardiomyopathy.

Momoi et al. (1992) reviewed the case histories of 19 Japanese patients with GSD IIIa who developed muscular symptoms at various ages. They divided the patients into 4 groups: one with childhood onset of both muscle weakness and hepatic disorders; one with onset of muscular symptoms in adulthood while liver symptoms started in childhood; one with muscle weakness starting in adulthood long after liver symptoms in childhood had disappeared; and one with only muscle symptoms as adults without any sign or history of liver dysfunction after childhood.

Coleman et al. (1992) studied 13 patients with GSD III followed from infancy. Activities of serum aspartate and alanine transaminases, lactate dehydrogenase, and alkaline phosphatase were markedly elevated during infancy. The serum enzyme activities declined around puberty concomitantly with a decrease in liver size. Although periportal fibrosis and micronodular cirrhosis indicated the presence of hepatocellular damage during childhood, the decline in serum enzyme activities with age and the absence of overt hepatic dysfunction suggested to the authors that the fibrotic process may not always progress.

Markowitz et al. (1993) described a white man in whom the diagnosis of GSD III was made on the basis of open liver biopsy at the age of 1 year. At the age of 31 years, he presented with variceal hemorrhage secondary to hepatic cirrhosis. No other cause of the cirrhosis was found, other than deficiency of debranching enzyme, which was documented both in liver and skeletal muscle.

In a multicenter study in the United States and Canada, Talente et al. (1994) identified 9 patients with GSD III who were 18 years of age or older. Increased creatine kinase activity was observed in 6 patients; 4 had myopathy and cardiomyopathy. One of the patients reported in detail was a 55-year-old man who owned and managed a small business. At age 30, he had gradual onset of weakness in his hands and feet. The distal muscles atrophied, and weakness progressed to include the limb-girdle region.

Hadjigeorgiou et al. (1999) reported 4 adult Italian patients with GSD IIIa confirmed by molecular analysis. All patients had a history of infantile hepatomegaly followed by myopathy in their twenties. AGL activity and protein were almost absent in muscle specimens. A remarkably severe clinical history was noted in 1 patient, who underwent liver transplantation at 23 years of age and developed a proximal myopathy and an obstructive hypertrophic cardiomyopathy by age 30 years.

In 7 patients with GSD III, Cleary et al. (2002) identified consistent facial features including midface hypoplasia with a depressed nasal bridge and a broad upturned nasal tip, indistinct philtral pillars, and bow-shaped lips with a thin vermilion border. In addition, younger patients had deep-set eyes. Several children had clinical problems such as persistent otitis media or recurrent sinusitis. The similar features in these patients suggested a distinct facial phenotype for this disorder.

Schoser et al. (2008) reported a family with variable presentation of GSD III. The 49-year-old female proband presented with hepatomegaly, cardiomyopathy, and moderate progressive proximal limb myopathy. She developed proximal muscle weakness at age 10 and signs and symptoms of cardiomyopathy at age 30. She also had progressive hearing impairment beginning at age 30. Skeletal muscle biopsy showed severe vacuolar myopathy with PAS-positive glycogen storage material that altered the contractile apparatus. Two brothers had died of severe infantile liver cirrhosis, and a sister died with cardiomyopathy, hepatomegaly, and myopathy at age 33. The proband was homozygous for a truncating mutation in the AGL gene. Heterozygous family members had exercise-inducted myalgia and weakness since their teens. Schoser et al. (2008) concluded that, with the exception of early infantile fatal cirrhosis, patients with GSD III may stay ambulatory until adulthood.

Aoyama et al. (2009) reported a 14-year-old Turkish girl with GSD type IIIc, or isolated glucosidase deficiency, due to homozygosity for an AGL mutation (R1147G; 610860.0014). She had mild hepatomegaly, but no clinical muscle involvement or hypoglycemia. The authors stated that this was the first molecular diagnosis in a patient with GSD IIIc.

Clinical Variability

Ebermann et al. (2008) reported an 11-year-old boy, born of Egyptian consanguineous parents, with a phenotype suggestive of Navajo neurohepatopathy (MTDPS6; 256810) including short stature, frequent painless fractures, bruises, and cuts, hepatomegaly with elevated liver enzymes, corneal ulcerations, and mild hypotonia. His 22-month-old sister had short stature, hepatomegaly, increased liver enzymes, and hypotonia. A cousin had died at age 8 years from liver failure. After genetic analysis excluded a mutation in the MPV17 gene (137960), Ebermann et al. (2008) postulated 2 recessive diseases. Genomewide linkage analysis and gene sequencing of the proband identified a homozygous mutation in the AGL gene, consistent with glycogen storage disease III, and a homozygous mutation in the SCN9A gene (603415), consistent with congenital insensitivity to pain (CIPA; 243000). His sister had the AGL mutation and GSD3 only. Ebermann et al. (2008) emphasized that consanguineous matings increase the risk of homozygous genotypes and recessive diseases, which may complicate genetic counseling.

Biochemical Features

Rosenfeld et al. (1976) reported 5 patients with GSD III from the USSR. All had hypoglycemia after an overnight fast. Liver glycogen was increased and there was complete absence of liver AGL activity. Two patients also had a decrease in liver phosphorylase (232700) activity, and another had a decrease in glucose-6-phosphatase (613742) activity.

By immunoblot studies, Chen et al. (1987) found absence of the glycogen debranching enzyme in liver and muscle samples from patients with GSD III. Cross-reactive material was detected in liver and muscle samples from patients with other types of glycogen storage disease, indicating that absence of the debranching enzyme in liver and muscle is specific for GSD III.

Diagnosis

Shen et al. (1997) used 3 polymorphic markers within the AGL gene for linkage analysis of GSD III and showed the potential use of these markers for carrier detection and prenatal diagnosis.

Molecular Genetics

In 3 unrelated patients with GSD IIIb, Shen et al. (1996) identified homozygous or compound heterozygous mutations in the AGL gene (see, e.g., 610860.0002-610860.0004). One of the mutations (17delAG; 610860.0004) was found in 8 of 10 additional GSD IIIb patients. Mutations in exon 3 were present in 12 of 13 GSD IIIb patients, suggesting a specific association. In addition, the identification of exon 3 mutations may have clinical significance because it can distinguish GSD IIIb from IIIa. The 3 patients with GSD IIIb in whom mutations were studied in detail were aged 25 years, 18 years, and 41 years; they had no clinical or laboratory evidence of myopathy or cardiomyopathy.

Shen et al. (1997) identified a homozygous mutation in the AGL gene (610860.0001) in a child with an unusually severe GSD IIIa phenotype. Okubo et al. (2000) identified 7 different mutations in the AGL gene, including 6 novel mutations, among 8 Japanese GSD IIIa patients from 7 families.

Shaiu et al. (2000) reported 2 frequent mutations, each of which was found in homozygous state in multiple patients, and each of which was associated with a subset of clinical phenotype in those patients with that mutation. One mutation (IVS32-12A-G; 610860.0006) was identified in homozygosity in a confirmed GSD IIIa Caucasian patient who presented with mild clinical symptoms. This mutation had an allele frequency of approximately 5.5% in GSD III patients tested. The other common mutation (3964delT; 610860.0010) was identified in an African American patient who had a severe phenotype and early onset of clinical symptoms. The mutation was later identified in several other patients and was observed at a frequency of approximately 6.7%. Together, these 2 mutations can account for more than 12% of the molecular defects in GSD III patients. Shaiu et al. (2000) also identified 6 additional mutations and reviewed the nonmutation state.

Lucchiari et al. (2002) identified 7 novel mutations of the AGL gene in patients with GSD IIIa in the Mediterranean area.

Endo et al. (2006) identified 9 different mutations in the AGL gene, including 6 novel mutations, among 9 patients with GSD III. The patients were from Germany, Canada, Afghanistan, Iran, and Turkey.

Aoyama et al. (2009) identified 10 different AGL mutations, including 8 novel mutations (see, e.g., 610860.0014 and 610860.0015), in 23 Turkish patients with GSD III. No genotype/phenotype correlations were observed.

Population Genetics

In Israel, 73% of glycogen storage disease was of type III. All cases were non-Ashkenazim, being mainly of North African extraction, in which group the incidence was 1 in 5,420 (Levin et al., 1967).

The overall incidence of GSD III is about 1 in 100,000 live births in the U.S.; however, it is unusually frequent among North African Jewish individuals in Israel (1 in 5,400 with a carrier frequency of 1 in 35) (Parvari et al., 1997).

Cohn et al. (1975) reported 2 families from the Faroe Islands with GSD III deficiency. The distribution supported the assumption of autosomal recessive inheritance. Santer et al. (2001) reported 5 families from the Faroe Islands affected with GSD IIIa. All carried the same mutation in the AGL gene (R408X; 610860.0013) and were homozygous for the same haplotype, supporting a founder effect. The results predicted a carrier frequency of 1 in 30 and a calculated prevalence of 1 per 3,600 in the Faroese population. The population of 45,000 of this small archipelago in the North Atlantic has its roots in the colonization by Norwegians in the 8th century and throughout the Viking Age. Santer et al. (2001) concluded that due to a founder effect, the Faroe Islands have the highest prevalence of GSD IIIa worldwide.

History

Fernandes (1995) stated that van Creveld (1928) published the first clinical description of a patient with glycogen storage disease, a 7-year-old boy who presented with a markedly enlarged liver, obesity, and small genitalia. The initial diagnosis of adiposogenital dystrophy had to be abandoned because of the further clinical and metabolic findings, the results of which were ingeniously interpreted as reflecting increased combustion of fat resulting from 'insufficient mobilization of glycogen.' This was the first reported patient with GSD III, as proved later enzymatically. The description of GSD I by von Gierke (1929) came next. Pompe (1932) described a case of 'idiopathic hypertrophy of the heart,' now known to be GSD II. (Pompe was a close friend of van Creveld and was killed by the Nazi Germans shortly before the liberation of the Netherlands in 1944.)

Animal Model

Ceh et al. (1976) described GSD III in the dog.