Ornithine transcarbamylase deficiency: a possible risk factor for thrombosis

Placental Pathology in Maternal Ornithine Transcarbamylase Deficiency

INTRODUCTION

Ornithine transcarbamylase (OTC) deficiency is the most common urea cycle disorder, inherited in an X-linked manner. Males are severely affected. Female phenotypes vary from asymptomatic to severe, and symptoms may be triggered by high metabolic states like childbirth. Literature on OTC deficiency in pregnancy and placental pathology is limited.

METHODS

Pathology records were searched at a single referral center from 2000-2020 and identified three placental cases from two mothers heterozygous for OTC deficiency. Placental pathology and maternal and neonatal history were reviewed in detail.

RESULTS

The placenta from one symptomatic mother carrying an affected male fetus showed widespread high-grade fetal vascular malperfusion (FVM) lesions of varying age. These lesions were not seen in the two placentas from the asymptomatic mother.

DISCUSSION

In cases of symptomatic maternal OTC deficiency, our findings highlight the need for placental examination. Since thrombotic events in the placenta have the potential to associate with fetal and neonatal endothelial damage, a high index of suspicion for neonatal thrombosis may be warranted.

Transient Cortical Blindness in a Toddler With Heterozygous Ornithine Transcarbamylase Deficiency

Ornithine transcarbamylase (OTC) deficiency is an incredibly rare disease in the subgroup of urea cycle disorders. Although typically seen in the neonate shortly after initiating high protein feeds (human breastmilk or infant formula), patients with partial/heterozygous deficiencies can often be diagnosed later in life with unique sequelae. One such manifestation is sudden, transient vision loss shortly after an initial episode of hyperammonemia in a patient without a known diagnosis of OTC deficiency. Only two such occurrences are documented in academic literature and both share many similar presenting features hinting that a hidden, but the consistent pathophysiologic mechanism of this disease is at play. Scarce research is available to propose a concise explanation; however, recent advancements in the literature point toward the brain’s inability to uptake glucose and convert it into glutamate in patients with partial OTC deficiency as a likely explanation.

Physical, cognitive, and social status of patients with urea cycle disorders in Japan

Urea cycle disorders (UCDs) are inherited metabolic diseases that lead to hyperammonemia. Severe hyperammonemia adversely affects the brain. Therefore, we conducted a nationwide study between January 2000 and March 2018 to understand the present status of UCD patients in Japan regarding diagnosis, treatments, and outcomes. A total of 229 patients with UCDs (126 patients: ornithine transcarbamylase deficiency [OTCD]; 33: carbamoyl phosphate synthetase 1 deficiency [CPS1D]; 48: argininosuccinate synthetase deficiency [ASSD]; 14: argininosuccinate lyase deficiency [ASLD]; and 8: arginase 1 deficiency [ARG1D]) were enrolled in the present study. Although growth impairment is common in patients with UCDs, we discovered that Japanese patients with UCDs were only slightly shorter than the mean height of the general adult population in Japan. Patients with neonatal-onset UCDs are more likely to experience difficulty finding employment and a spouse; however, some patients with late-onset UCDs were employed and married. Additionally, intellectual and developmental disabilities, such as attention deficit hyperactivity disorder (ADHD) and autism, hinder patients with UCDs from achieving a healthy social life. Moreover, we identified that it is vital for patients with UCDs presenting with mild to moderate intellectual disabilities to receive social support. Therefore, we believe the more robust social support system for patients with UCDs may enable them to actively participate in society.

SARS CoV2 infection in a young subject affected by arginosuccinate synthase deficiency: A case report of epilepsy worsening

We describe a case of a 21 years old woman affected by Citrullinemia type 1- Arginosuccinate Synthase deficiency (ASSD)-who underwent a SARS CoV2 infection during the first phase of pandemic burst in Italy. She had no symptoms of infection nor a metabolic crisis. After recovery from SARS CoV2, she experienced a worsening in their epilepsy despite therapy, with one/two crisis a week.

Two novel mutations of ornithine transcarbamylase gene identified from three Chinese neonates with ornithine transcarbamylase deficiency

We aim to analyze the blood metabolic profiling and the gene mutation of ornithine transcarbamylase (OTC) in three neonates with ornithine transcarbamylase deficiency (OTCD). Three neonates with OTCD were included in this study. The profiling of amino acids and acylcarnitine was determined using MS-MS assay. The OTC exons were amplified using PCR amplification. DNA sequencing was performed, based on which mutation analysis of OTC genes was carried out. For the clinical symptoms, all the three neonates showed poor reaction and feeding. In addition, convulsion and neonatal infection were noticed. A remarkable decrease of citrulline concentration was revealed by MS-MS assay. In case 1, a 548A > G substitution was identified in exon 6, which resulted in replacement of cysteine by tyrosine in codon 183. In case 2, a 1016T > G substitution was identified in exon 10, leading to replacement of valine by glycine in codon 339. In case 3, a 995G > C mutation was noted in exon 9, resulting in missense mutation of tryptophane to serine in codon332. Three types of OTC gene mutations were identified in Chinese neonates with OTC deficiency, among which two novel mutations, including 1016T > G and 995G > C, are presented uniquely in our study.

Hyperammonemia due to urea cycle disorders: a potentially fatal condition in the intensive care setting

Disorders of the urea cycle are secondary to a defect in the system that converts ammonia into urea, resulting in accumulation of ammonia and other products. This results in encephalopathy, coma, and death if not recognized and treated rapidly. Late-onset urea cycle disorders may be precipitated by acute disease and can be difficult to recognize because patients are already ill. Diagnosis of urea cycle disorders is based on clinical suspicion and determination of blood ammonia in suspected patients with neurological symptoms in the intensive care setting. Treatment is based on the removal of ammonia by dialysis or hemofiltration, reduction of the catabolic state, abolishment of nitrogen administration, and use of pharmacological nitrogen scavenging agents.