Pituitary hypoplasia and growth hormone deficiency in a woman with glycogen storage disease type Ia: a case report

Isolated short stature as the only presenting symptom of glycogen storage disease type 0a in a Chinese child: A case report

RATIONALE

Glycogen storage disease type 0a (GSD0a) is a rare autosomal recessive disorder caused by glycogen synthase deficiency. Short stature is a characteristic feature in 29% of GSD0a patients, but isolated short stature as the only presenting symptom is exceedingly rare, with only 2 cases reported worldwide.

PATIENT CONCERNS

A 4-year-old girl presented with persistent growth retardation despite previous treatment for renal tubular acidosis.

DIAGNOSES

Based on clinical presentation and whole exome sequencing results, the patient was diagnosed with GSD0a.

INTERVENTIONS

Uncooked cornstarch therapy was initiated at 2 g/kg every 6 hours.

OUTCOMES

After 3 years of treatment, the patient's height SDS improved from -2.24 to -1.06, with enhanced glycemic control and no complications.

LESSONS

This case emphasizes considering GSD0a in unexplained short stature and the value of continuous glucose monitoring. Early diagnosis and treatment can optimize growth in GSD0a patients.

Endocrine involvement in hepatic glycogen storage diseases: pathophysiology and implications for care

Hepatic glycogen storage diseases constitute a group of disorders due to defects in the enzymes and transporters involved in glycogen breakdown and synthesis in the liver. Although hypoglycemia and hepatomegaly are the primary manifestations of (most of) hepatic GSDs, involvement of the endocrine system has been reported at multiple levels in individuals with hepatic GSDs. While some endocrine abnormalities (e.g., hypothalamic‑pituitary axis dysfunction in GSD I) can be direct consequence of the genetic defect itself, others (e.g., osteopenia in GSD Ib, insulin-resistance in GSD I and GSD III) may be triggered by the (dietary/medical) treatment. Being aware of the endocrine abnormalities occurring in hepatic GSDs is essential (1) to provide optimized medical care to this group of individuals and (2) to drive research aiming at understanding the disease pathophysiology. In this review, a thorough description of the endocrine manifestations in individuals with hepatic GSDs is presented, including pathophysiological and clinical implications.

Case Report: Glycogen Storage Disease Type Ia in a Chinese Child Treated With Growth Hormone

BACKGROUND

Glycogen storage disease type Ia is a rare metabolic disorder that leads to excessive glycogen and fat accumulation in organs, characterized by hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia, hyperuricemia, puberty delay, and growth retardation. Here, we report on a patient with glycogen storage disease type Ia treated with growth hormone.

CASE PRESENTATION

A 10-year-old boy had growth retardation for 6 years, and was admitted to clarify the cause of his short stature. We found that his bone age was 5.5 years, significantly lower than his physical age, while his serum IGF-1 and IGFBP-3 were 23.30 and 1620.0 ng/mL, respectively, both lower than normal. His medical history revealed that he had suffered from steatohepatitis, hyperlipidemia, and hypoglycemia since he was 11 months of age. Whole exome sequencing (WES) showed compound heterozygous mutations in exons 2 and 5 of the glucose-6-phosphatase (G6PC) gene on chromosome 17: c.G248A (p.R83H) and c.G648T (p.L216L). The patient was finally diagnosed with GSD Ia. After growth hormone (GH) treatment and corn starch therapy for 14 months, his height significantly increased (by 13 cm). The serum IGF-1 level increased to the normal range but his lipid levels and liver function did not significantly increase.

CONCLUSION

We describe a young patient with a compound heterozygous G6PC variant in a Chinese family; his height increased significantly after growth hormone and corn starch interventions. This case emphasizes that WES is essential for early diagnosis, and that growth hormone treatment may increase the height of patients with GSD Ia safely.

The natural history of glycogen storage disease type Ib in England: A multisite survey

Glycogen storage disease type Ib (GSDIb) is characterized by hepatomegaly and fasting hypoglycaemia as well as neutropaenia and recurrent infections. We conducted a retrospective observational study on a cohort of patients with GSDIb across England. A total of 35 patients, with a median age of 9.1 years (range 1-39 years), were included in the study. We examined the genotype and phenotype of all patients and reported 14 novel alleles. The phenotype of GSDIb in England involves a short fasting tolerance that extends into adulthood and a high prevalence of gastrointestinal symptoms. Growth is difficult to manage and neutropaenia and recurrent infections persist throughout life. Liver transplantation was performed in nine patients, which normalized fasting tolerance but did not correct neutropaenia. This is the first natural history study on the cohort of GSDIb patients in England.

Glycogen storage disease type IX and growth hormone deficiency presenting as severe ketotic hypoglycemia

BACKGROUND

Glycogen storage disease (GSD) type IX and growth hormone (GH) deficiency cause ketotic hypoglycemia via different mechanisms and are not known to be associated. We describe a patient presenting with severe ketotic hypoglycemia found to have both GSD IX and isolated GH deficiency.

CASE PRESENTATION

A 3-year-and-11-month-old boy with a history of prematurity, autism, developmental delay, seizures, and feeding difficulty was admitted for poor weight gain and symptomatic hypoglycemia. He was nondysmorphic, with a height of 93.8 cm (2%, -1.97 SDS), and has no hepatomegaly. He developed symptomatic hypoglycemia, with a serum glucose level of 37 mg/dL after 14 h of fasting challenge. Critical sample showed a GH of 0.24 ng/mL. GH provocative stimulation testing was done with a peak GH of 2.8 ng/mL. Brain magnetic resonance imaging showed a hypoplastic pituitary gland. Given the clinical symptoms, suspicion for mitochondrial disease was high. Dual Genome Panel by Massively Parallel Sequencing revealed a hemizygous variant c.721A>G (p1241V) in the X-linked PHKA2 gene, a causative gene for GSD IX. Red blood cell PhK enzyme activity testing was low, supporting the diagnosis.

CONCLUSIONS

Given the patient's developmental delays that were not explained by GH deficiency alone, further investigation showed two unrelated conditions resulting in deranged metabolic adaptation to fasting leading to severe hypoglycemia.

Pathogenesis of growth failure and partial reversal with gene therapy in murine and canine Glycogen Storage Disease type Ia

Glycogen Storage Disease type Ia (GSD-Ia) in humans frequently causes delayed bone maturation, decrease in final adult height, and decreased growth velocity. This study evaluates the pathogenesis of growth failure and the effect of gene therapy on growth in GSD-Ia affected dogs and mice. Here we found that homozygous G6pase (-/-) mice with GSD-Ia have normal growth hormone (GH) levels in response to hypoglycemia, decreased insulin-like growth factor (IGF) 1 levels, and attenuated weight gain following administration of GH. Expression of hepatic GH receptor and IGF 1 mRNAs and hepatic STAT5 (phospho Y694) protein levels are reduced prior to and after GH administration, indicating GH resistance. However, restoration of G6Pase expression in the liver by treatment with adeno-associated virus 8 pseudotyped vector expressing G6Pase (AAV2/8-G6Pase) corrected body weight, but failed to normalize plasma IGF 1 in G6pase (-/-) mice. Untreated G6pase (-/-) mice also demonstrated severe delay of growth plate ossification at 12 days of age; those treated with AAV2/8-G6Pase at 14 days of age demonstrated skeletal dysplasia and limb shortening when analyzed radiographically at 6 months of age, in spite of apparent metabolic correction. Moreover, gene therapy with AAV2/9-G6Pase only partially corrected growth in GSD-Ia affected dogs as detected by weight and bone measurements and serum IGF 1 concentrations were persistently low in treated dogs. We also found that heterozygous GSD-Ia carrier dogs had decreased serum IGF 1, adult body weights and bone dimensions compared to wild-type littermates. In sum, these findings suggest that growth failure in GSD-Ia results, at least in part, from hepatic GH resistance. In addition, gene therapy improved growth in addition to promoting long-term survival in dogs and mice with GSD-Ia.