Beta-ketothiolase deficiency and pregnancy

Diabetic ketoacidosis in an adult with beta-ketothiolase deficiency (BKD) involving a novel ACAT1 variant : first report of established diabetes in BKD and a review of the literature

BACKGROUND

Diabetes presenting in young adults is often challenging to classify. Diabetic ketoacidosis is typically seen in autoimmune type 1 diabetes mellitus and more rarely in young onset type 2 diabetes mellitus. Beta-ketothiolase deficiency (BKD) is a rare autosomal recessive condition affecting isoleucine catabolism and ketone body metabolism. BKD typically manifests in childhood as recurrent episodes of ketoacidosis, the frequency of which tends to reduce with age. There is a paucity of data with respect to the co-existence of persistent dysglycemia with BKD.

CASE PRESENTATION AND LITERATURE REVIEW

We present a novel case of diabetes presenting as diabetic ketoacidosis in a 34-year-old man with BKD, with genetically confirmed compound heterozygosity for variants in ACAT1, including a novel ACAT1 c.481T>C, p.(Tyr161His) variant. Diabetes in people with BKD presents unique diagnostic and management challenges. To further contextualize our findings, we conducted a comprehensive narrative review of the existing literature with respect to dysglycemia in those with BKD, especially in adulthood. There are no existing reports describing diabetes in adults with BKD. Stress hyperglycemia is not uncommon when children with BKD are acutely unwell, with several pediatric case reports describing short-lived hyperglycemia but normal HbA1c measurements during metabolic crises (indicating the absence of persistent hyperglycemia).

CONCLUSIONS

This is the first report of diabetic ketoacidosis in an adult with BKD, with an elevated HbA1c consistent with persistent hyperglycemia. This case highlights the importance of checking HbA1c in people with BKD and hyperglycemia in order to uncover potential coexisting diabetes, facilitating timely management and preventing complications. Increased reporting on the longitudinal outcomes of those with rare metabolic disorders is essential for identifying potential associations with conditions like diabetes.

2-methylacetoacetyl-coenzyme A thiolase (beta-ketothiolase) deficiency: one disease - two pathways

Background

2-methylacetoacetyl-coenzyme A thiolase deficiency (MATD; deficiency of mitochondrial acetoacetyl-coenzyme A thiolase T2/ “beta-ketothiolase”) is an autosomal recessive disorder of ketone body utilization and isoleucine degradation due to mutations in ACAT1.

Methods

We performed a systematic literature search for all available clinical descriptions of patients with MATD. Two hundred forty-four patients were identified and included in this analysis. Clinical course and biochemical data are presented and discussed.

Results

For 89.6% of patients at least one acute metabolic decompensation was reported. Age at first symptoms ranged from 2 days to 8 years (median 12 months). More than 82% of patients presented in the first 2 years of life, while manifestation in the neonatal period was the exception (3.4%). 77.0% (157 of 204 patients) of patients showed normal psychomotor development without neurologic abnormalities.

Conclusion

This comprehensive data analysis provides a systematic overview on all cases with MATD identified in the literature. It demonstrates that MATD is a rather benign disorder with often favourable outcome, when compared with many other organic acidurias.

Alpha-Methylacetoacetic Aciduria in an Rh-Negative Pregnant Omani Woman With Breech Presentation Delivered With Favourable Outcome

BACKGROUND

Alpha-methylacetoacetic aciduria, an autosomal recessive disorder of isoleucine and ketone body metabolism, is caused by a mutation in the acetyl coenzyme A acetyltransferase-1 gene (ACAT1; 607809) on chromosome 11q22. Ketoacidotic episodes in such patients are triggered by stress situations with increased energy demands. Pregnancy, surgical procedures, and prolonged fasting are potential triggers for metabolic crisis in such cases.

CASE

A young Rh-negative Omani woman with alpha-methylacetoacetic aciduria is described here during her second pregnancy. Her metabolic condition was detected at the age of 18 months. She was successfully delivered of a clinically healthy baby through emergency CS for breech presentation.

CONCLUSION

Prompt management by a multidisciplinary team is vital to avoid metabolic crisis and to promote a favourable outcome in these cases.

Impact of pregnancy on inborn errors of metabolism

Once based mainly in paediatrics, inborn errors of metabolism (IEM), or inherited metabolic disorders (IMD) represent a growing adult medicine specialty. Individually rare these conditions have currently, a collective estimated prevalence of >1:800. Diagnosis has improved through expanded newborn screening programs, identification of potentially affected family members and greater awareness of symptomatic presentations in adolescence and in adulthood. Better survival and reduced mortality from previously lethal and debilitating conditions means greater numbers transition to adulthood. Pregnancy, once contraindicated for many, may represent a challenging but successful outcome. Successful pregnancies are now reported in a wide range of IEM. Significant challenges remain, given the biological stresses of pregnancy, parturition and the puerperium. Known diagnoses allow preventive and pre-emptive management. Unrecognized metabolic disorders especially, remain a preventable cause of maternal and neonatal mortality and morbidity. Increased awareness of these conditions amongst all clinicians is essential to expedite diagnosis and manage appropriately. This review aims to describe normal adaptations to pregnancy and discuss how various types of IEM may be affected. Relevant translational research and clinical experience will be reviewed with practical management aspects cited. Based on current literature, the impact of maternal IEM on mother and/or foetus, as well as how foetal IEM may affect the mother, will be considered. Insights gained from these rare disorders to more common conditions will be explored. Gaps in the literature, unanswered questions and steps to enhance further knowledge and systematically capture experience, such as establishment of an IEM-pregnancy registry, will be summarized.