GPD1 Deficiency - Underdiagnosed Cause of Liver Disease

Glycerol-3-Phosphate Dehydrogenase 1 Deficiency and Steatotic Liver Disease in Children: Our Cases and Review of Literature

Introduction

Glycerol-3-phosphate dehydrogenase 1 (GPD1) deficiency is an autosomal recessive disorder causing hypertriglyceridemia, hepatomegaly, fatty liver, and hepatic fibrosis in infancy. It is an under-recognized cause of pediatric steatotic liver disease (SLD) with only 36 cases reported worldwide.

Method

We analyzed the clinical profile of our five cases diagnosed by exome sequencing (ES) and reviewed the published cases till December 2023 using PubMed search.

Results

Five unrelated boys (6-24months) presented with hepatomegaly, hypertriglyceridemia, transaminase elevation, and fatty liver. ES revealed compound heterozygous mutations in two and homozygous mutation in three including two novel mutations (c.917T >C, c.905C > G). All received supportive therapy, and fenofibrate was successfully used in one case for progressive hypertriglyceridemia. Globally, 36 cases (age at diagnosis: 6 [1-164 months]) have been reported. Majority had hepatomegaly (94.4%), 22.2% each had splenomegaly and growth failure. Hypertriglyceridemia (97.2%) was nearly universal, 100% had fatty liver, and hypoglycaemia (11.2%) was uncommon. Liver biopsy (n = 18) demonstrated steatosis in all, fibrosis in 94.4%, and cirrhosis in 22.2%. During follow-up (11-376 months), hepatomegaly resolved in 35.2%, triglycerides, and transaminases normalized in 29.1% and 31.5%, respectively. No pancreatitis, cardiac events, or liver decompensation was reported.

Conclusion

GPD1 is an uncommon cause of SLD, raised transaminases and hypertriglyceridemia in young children. Diagnosis is confirmed by genetic testing. Supportive therapy, parental counseling about the disease nature and close follow-up is recommended.

Identification of a novel heterozygous GPD1 missense variant in a Chinese adult patient with recurrent HTG-AP consuming a high-fat diet and heavy smoking

BACKGROUND

Glycerol-3-phosphate dehydrogenase 1 (GPD1) gene defect can cause hypertriglyceridemia (HTG), which usually occurs in infants. The gene defect has rarely been reported in adult HTG patients. In the present study, we described the clinical and functional analyses of a novel GPD1 missense variant in a Chinese adult patient with recurrent hypertriglyceridemia‑related acute pancreatitis (HTG-AP), consuming a high-fat diet and smoking heavily.

METHODS

Exome sequencing was used to analyze the DNA of the adult patient's blood sample. It was found that there was a new variant of GPD1 gene-p.K327N, which was verified by gold standard-sanger sequencing method. In vitro, the corresponding plasmid was constructed and transfected into human renal HEK-293T cells, and GPD1 protein levels were detected. A biogenic analysis was performed to study the population frequency, conservation, and electric potential diagram of the new variant p.K327N. Finally, the previously reported GPD1 variants were sorted and their phenotypic relationships were compared.

RESULTS

A novel heterozygous variant of GPD1, p.K327N (c.981G > C), was found in the proband. Furthermore, the patient's daughter carried this variant, whereas his wife did not carry the variant. The proband with obesity suffered eight episodes of HTG-AP from the age of 36 years, and each onset of AP was correlated to high-fat diet consumption and heavy smoking. In vitro, this variant exerted a relatively mild effect on GPD1 functions, which were associated with its effect upon secretion (~ 25% of secretion decreased compared with that of the wild-type); thus, eventually impairing protein synthesis. Additionally, 36 patients with GPD1 variants found in previous studies showed significant transient HTG in infancy. The proband carrying the GDP1 variant was the first reported adult with recurrent HTG-AP.

CONCLUSION

We identified a novel GPD1 variant, p.K327N, in a Chinese adult male patient with recurrent HTG-AP. The variant probably exerted a mild effect on GPD1 functions. The heterozygosity of this GPD1 variant, in addition to high-fat diet consumption and heavy smoking, probably triggered HTG-AP in the patient.

Clinical characteristics and variant analyses of transient infantile hypertriglyceridemia related to GPD1 gene

Objective: Our study aims to summarize and analyze the clinical characteristics of transient infantile hypertriglyceridemia (HTGTI) and variants in the glycerol-3-phosphate dehydrogenase 1 (GPD1) gene and the effect of HTGTI on the protein structure of GPD1.

Methods: Retrospective analysis, using the general data, symptoms, signs, and auxiliary examinations, was performed on patients with HTGTI, which were confirmed by genetic testing in our hospital and reported cases online. The clinical data were analyzed using statistical and bioinformatic approaches.

Results: A total of 31 genetically confirmed HTGTI patients were collected from our hospital and cases reported in the literature. The clinical manifestations showed the median age of onset was 6.0 (1.9, 12.0) months. All the patients had normal psychiatric status, but 22.6% of them presented growth retardation and short stature, 93.5% had hepatomegaly, and 16.1% had splenomegaly. Just a few children were reported with jaundice, cholestasis, and obesity (3.2–6.5%). The laboratory investigations showed that 96.8% of them had hypertriglyceridemia (HTG) with a median level of 3.1 (2.1, 5.5) mmol/L, but only 30.0% had returned to normal during follow-up. In addition, 93.5% of patients had elevated alanine aminotransferase (ALT) with an average level of 92.1 ± 43.5 U/L, while 38.7% had hypercholesterolemia. Upon abdominal imaging, all patients presented fatty liver and liver steatosis, with 66.7% of patients showing hepatic fibrosis. Statistical differences in triglyceride (TG) level were observed in the ≤6 months group compared with the older groups and in the 13 months to 6 years group with >6 years group (H = 22.02, P < 0.05). The restricted cubic spline model showed that severe HTG decreased in the early stage of infants to the normal level; however, it rebounded again to a mild or moderate level after the following days. The genetic test revealed that the main variant types of the GPD1 gene were missense variants (51.6%), followed by splicing variants (35.5%) and nonsense variants (12.9%). Of patients, 87.1% had homozygous variants, with the most frequent loci being c.361-1G > C and c.895G > A.

Conclusion: The common manifestations of HTGTI were HTG, hepatomegaly, elevated liver transaminases, and hepatic steatosis in early infancy. However, the recurrence of aberrant HTG may pose long-term detrimental effects on HTGTI patients.

Case of GPD1 deficiency causing hypertriglyceridaemia and non-alcoholic steatohepatitis

We report a case of a young girl of South Asian descent presented with faltering growth, hepatomegaly, hypertriglyceridaemia and raised transaminases. Subsequent ultrasound scans identified fatty infiltration in her liver, and a liver biopsy showed fibrosis and steatosis. The patient's serum triglycerides normalised without intervention by the age of 28 months. At age 6, whole-exome sequencing of the patient's genome identified novel homozygous variants in the glycerol-3-phosphate dehydrogenase 1 (GPD1) gene, GPD1 c.500G>A (p.Gly167Asp), leading to a diagnosis of GPD1 deficiency.