Novel CAD gene mutations in a boy with developmental and epileptic encephalopathy 50 with dramatic response to uridine therapy: a case report and a review of the literature

BACKGROUND

Developmental and epileptic encephalopathy-50 (DEE-50) is a rare clinical condition believed to be caused by a mutation in the CAD gene and is associated with a bleak prognosis. CAD-related diseases have a wide range of clinical manifestations and other symptoms that may be easily overlooked. Like other rare diseases, the clinical manifestations and the treatment of DEE-50 necessitate further investigation.

CASE PRESENTATION

A 1-year-old male patient presented with developmental delay, seizures, and anaemia at 3 months of age. He further developed refractory status epilepticus (SE), rapid deterioration of cognitive and motor function, and even became comatose at 5 months of age. Whole-exome sequencing of trios (WES-trios) revealed a compound heterozygous variant in the CAD gene, with one locus inherited from his father (c.1252C>T: p.Q418* nonsense mutation) and one from his mother (c.6628G>A: p.G2210S, missense mutation). This compound heterozygous CAD variant was unreported in the Human Gene Mutation Database. After uridine treatment, his cognitive faculties dramatically improved and he remained seizure-free. Forty two cases with CAD gene mutation reported in the literatures were reviewed. Among them, 90% had onset before 3 years of age, with average of 1.6±1.8 years old. The average age of diagnosis was 7.7 ± 10 years. The mortality rate was approximately 9.5%, with all reported deaths occurring in patients without uridine treatment. The clinical entity could be improved dramatically when the patient treated with uridine.

CONCLUSIONS

We present a boy with DEE 50 caused by novel CAD gene mutations and reviewed the clinical features of 42 patients reported previously. DEE 50 has early onset, refractory seizures, even status epilepticus leading to death, with favorable response to treatment with oral uridine. Early uridine treatment is recommended if CAD defect is suspected or genetically diagnosed. This study enhances the knowledge of DEE 50 and expands the spectrum of CAD gene mutations.

Local anesthetic systemic toxicity in the pediatric patient: A case report and review of the literature

Lidocaine and prilocaine are local anesthetics, a class of medications which are frequently used in clinical medicine to minimize pain in a variety of procedures. They are commonly found in over-the-counter products such as topical anesthetic creams advertised to relieve localized muscle and joint pain. While safe and well-tolerated when used appropriately, an overdose of these anesthetics increases the risk for local anesthetic systemic toxicity (LAST), which in severe cases can present with seizures, cardiac dysrhythmias, and ultimately cardiovascular collapse. The reduced muscle mass of pediatric patients puts them at an increased risk of LAST due to the depot effect of the systemically absorbed anesthetic. Methemoglobinemia may also be associated with local anesthetic toxicity. Our case involves a previously healthy 15-month-old female who presented to one of our networks' emergency departments in status epilepticus following an accidental ingestion of a tube of 2.5% lidocaine/2.5% prilocaine cream. Her seizure activity was initially resistant to intraosseous benzodiazepine administration, but ultimately resolved following administration of lipid emulsion and sodium bicarbonate. Additionally, the patient had refractory hypoxia on the monitor which resolved shortly after administration of methylene blue. After stabilization, the patient was transferred to the Pediatric ICU and ultimately made a complete recovery. LAST is a life-threatening presentation which requires early recognition by clinicians, as well as an understanding of the appropriate treatment modalities. We review the assessment and management of LAST, with special focus on the pediatric patient.