The Role of Liver Transplantation in Propionic Acidemia.

Abstract

Dear Editor, To the Editor: We read with interest the article on liver transplantation (LT) for propionic acidemia (PA) by Quintero et al.1 We congratulate the authors on their series and for presenting the outcomes with all their granularity. The authors addressed this niche area and have provided a comprehensive overview on the management of PA. We would like to highlight some aspects of this study that will benefit from further clarification. We will also present our philosophy of managing these children and share our experience of LT for PA. As suggested in the literature and as seen in the authors’ series, hepatic artery thrombosis (HAT) is known to be comparatively more common in these patients.1 Even though several postulates exist, the reasons for this, unfortunately, remain unknown. The authors had a 50% hepatic artery issue with 2 HAT and 1 vasospasm in their series of 6 patients. This is rather concerning. It would be interesting to know the authors’ cumulative HAT rates. Have the authors changed or modified their technique for these patients? A note on it would help surgeons be aware of the fragility plaguing these arteries. Our own series consisted of 6 patients with PA, of whom 5 underwent auxiliary partial orthotopic liver transplantation (APOLT) and 1 orthotopic liver transplantation (OLT). There was 1 HAT. An immediate surgical revascularization was done, and the child made a complete recovery. In our pediatric LT series of 308 patients, we had 3 patients with HAT (0.97%), thus concurring with the authors’ series of a higher‐than‐average rate of arterial issues. Three of our PA patients presented with a history of poor feeding, encephalopathy, acidosis, and hyperammonemia. Two were diagnosed prenatally by genetic assay. One child did not have any metabolic decompensation prior to LT and had normal developmental milestones. The parents opted for LT because caring for the child was restricting the quality of life of the parents and siblings. Difficulty in procuring special feeds remains a significant concern for patients from Third World countries prior to LT; it has to be imported and can be prohibitively expensive. Three patients were on carglumic acid, 2 were on sodium benzoate, and all received carnitine and biotin prior to APOLT. It would be interesting to note if such nonmedical but extremely pertinent issues afflict other specialized centers dealing with metabolic liver diseases. As shown in the authors’ series, cardiac comorbidities are common in organic acidemic children and can adversely influence outcomes. One of our patients had a dilated left ventricle (LV) with hypokinesia (LV ejection fraction was 45%) and hypertension. Cardiomyopathy and hypertension did not progress after LT and has remained stable on a follow‐up of 50 months. In our unit, APOLT is considered as the first option for selected noncirrhotic metabolic liver diseases (NCMLDs), including Crigler‐Najjar syndrome (CNS) type 1, urea cycle disorders, and organic acidemias. OLT in these instances is only performed for small babies (weight <5 kg and age <6 months), or in accordance with the family’s wishes. APOLT provides intraoperative and perioperative stability because there is no anhepatic phase during surgery, potentially eliminating the risk of a metabolic crisis during the time period in these disorders. In the early postoperative period, the normally functioning native liver reduces the systemic effect of graft dysfunction, which gives the patient and the graft an opportunity to recover.2 Graft failure is also not an immediate threat to the patient’s life as in the case of OLT. This is particularly advantageous in children with PA where graft dysfunction after OLT can precipitate severe metabolic stress and decompensation.2 We had 1 mortality in our series of 6 patients, which was the child who underwent OLT. This death was due to graft dysfunction leading to severe metabolic decompensation, a situation which may have been obviated if the child had received an APOLT. As compared with other indications for APOLT in NCMLDs, a larger liver volume may be required in children with organic acidemia to avoid or mitigate a metabolic crisis in the immediate postoperative period.2 We would once again like to congratulate the authors for their series and, as stated by them, would like to see their follow‐up outcomes and results with APOLT. Potential conflict of interest Nothing to report.