The incidence of succinic semialdehyde dehydrogenase (SSADH) deficiency, an autosomal recessive inherited disorder of GABA degradation, is unknown. Upon a recent diagnosis of a new family of affected fraternal twins from the Punjabi ethnic group of India, case ascertainment from the literature and our database was done to determine the number of confirmed cases along with their geographic distribution. The probands presented with global developmental delay, infantile onset epilepsy, and a persistent neurodevelopmental disorder upon diagnosis at 10 years of age with intellectual disability, expressive aphasia, and behavioral problems most prominent for hyperactivity. Gamma-hydroxybutyric aciduria and homozygous ALDH5A1 c.608C>T; p.Pro203Leu mutations were confirmed. Identification of all available individual cases with clinical details available including geographic or ethnic origin revealed 182 patients from 40 countries, with the largest number of patients reported from the USA (24%), Turkey (10%), China (7%), Saudi Arabia (6%), and Germany (5%). This study provides an accounting of all published cases of confirmed SSADH deficiency and provides data useful in planning further studies of this rare inborn error of metabolism.

Objective Pediatric dystonic storm is an underrecognized entity. We aimed to evaluate the profiles of children presenting with dystonic storm in a referral hospital. Management schema and treatment responsiveness of this uncommonly reported entity were analyzed. Methods Retrospective review of all children (up to 18 years) hospitalized with dystonic storm over 39 months in the aforementioned facility. Results Twenty-three children whose ages ranged from 2 years 2 months to 14 years 4 months years (median: 6 years 11 months) (males: 13, females: 11) presented with dystonic storm. The annual incidence was 0.4 per 1,000 fresh admissions with an event rate of 0.9 per 1,000 for all admissions. All had Dystonia Severity Action Plan grades 4/5 with identifiable trigger in 13 (50%). Underlying dystonic disorder preexisted in 10 (43.4%); 8 of these had cerebral palsy. Polypharmacotherapy with >4 drugs out of trihexyphenidyl, tetrabenazine, clonazepam, gabapentin, levodopa-carbidopa, trichlorophos, and melatonin was needed. Supportive care and adequate sedation helped in symptom control. All children were managed with midazolam infusion over 2–10 days (median: 5 days). Mechanical ventilation was resorted to in 6 children (3–22 days). Vecuronium and propofol were used in 3/23 (13%) and 4/23 (17%) children, respectively. Deep brain stimulation was curative in 1 child. Hospitalization ranged from 5 to 31 (median: 11) days. Although there were no deaths, rhabdomyolysis was noted in 1 child. Postdischarge, 6 (26%) children relapsed. Conclusions Dystonic storm is a medical emergency mandating aggressive multimodal management. Supportive care, antidystonic drugs, and early elective ventilation alongside adequate sedation with benzodiazepines ameliorate complications. Relapses of dystonic storm are not uncommon.

POLG pathogenic variants are the commonest single-gene cause of inherited mitochondrial disease. However, the data on clinicogenetic associations in POLG-related disorders are sparse. This study maps the clinicogenetic spectrum of POLG-related disorders in the pediatric population. Individuals were recruited across 6 centers in India. Children diagnosed between January 2015 and August 2020 with pathogenic or likely pathogenic POLG variants and age of onset <15 years were eligible. Phenotypically, patients were categorized into Alpers-Huttenlocher syndrome; myocerebrohepatopathy syndrome; myoclonic epilepsy, myopathy, and sensory ataxia; ataxia-neuropathy spectrum; Leigh disease; and autosomal dominant / recessive progressive external ophthalmoplegia. A total of 3729 genetic reports and 4256 hospital records were screened. Twenty-two patients with pathogenic variants were included. Phenotypically, patients were classifiable into Alpers-Huttenlocher syndrome (8/22; 36.4%), progressive external ophthalmoplegia (8/22; 36.4%), Leigh disease (2/22; 9.1%), ataxia-neuropathy spectrum (2/22; 9.1%), and unclassified (2/22; 9.1%). The prominent clinical manifestations included developmental delay (n = 14; 63.7%), neuroregression (n = 14; 63.7%), encephalopathy (n = 11; 50%), epilepsy (n = 11; 50%), ophthalmoplegia (n = 8; 36.4%), and liver dysfunction (n = 8; 36.4%). Forty-four pathogenic variants were identified at 13 loci, and these were clustered at exonuclease (18/44; 40.9%), linker (13/44; 29.5%), polymerase (10/44; 22.7%), and N-terminal domains (3/44; 6.8%). Genotype-phenotype analysis suggested that serious outcomes including neuroregression (odds ratio [OR] 11, 95% CI 2.5, 41), epilepsy (OR 9, 95% CI 2.4, 39), encephalopathy (OR 5.7, 95% CI 1.4, 19), and hepatic dysfunction (OR 4.6, 95% CI 21.3, 15) were associated with at least 1 variant involving linker or polymerase domain. We describe the clinical subgroups and their associations with different POLG domains. These can aid in the development of follow-up and management strategies of presymptomatic individuals.

Ten days after the second cycle of HD-MTX, the patient was admitted with choreoathetoid movements with preserved sensorium (video 1). No other abnormality was noted on CNS examination. Complete blood count and biochemical parameters were normal. CSF was normal and did not reveal blasts. He was managed with oral trihexyphenidyl and clonazepam. Abnormal movements were controlled within 6 hours. MRI of the brain performed after 4 days was suggestive of MTX-induced leucoencephalopathy (figure 1A,B). Trihexyphenidyl and clonazepam were tapered and stopped, while levetiracetam was continued. Serum MTX levels at 36 hours after the start of MTX during cycles 1 and 2 were 1.82 µmol/L and 1.36 µmol/L (normal value <3 µmol/L). He was rechallenged with two more cycles of HD-MTX and did not have any recurrence of symptoms suggestive of MTX-induced encephalopathy.

The author needs to be complimented for an introspective and original work on an entity with multiple grey areas. The strengths of the article are as follows: (a) Choice of the topic, which is relevant and contemporary. With the increase in the numb...