Autonomic instability, arrhythmia and visual impairment in a new presentation of MTFMT-related mitochondrial disease.

Mitochondrial methionyl-tRNA formyltransferase (MTFMT) is required for the initiation of translation in mitochondria. Pathogenic variants in MTFMT have been described in association with clinical presentations with Leigh syndrome, as well with as multisystem involvement (particularly cardiac and ocular involvement). There is a spectrum of severity, but many reported presentations have been milder with a better prognosis than other pathogenic variants associated with Leigh syndrome. We describe the case of a 9-year-old boy homozygous for a pathogenic MTFMT variant (c.626C > T/p.Ser209Leu) who presented with hypertensive crisis on a background of hyperphagia and visual impairment. His clinical course was complicated by supraventricular tachycardia and severe autonomic instability, requiring intensive care unit admission. He also developed seizures, neurogenic bladder and bowel and had a markedly abnormal eye examination with bilateral optic atrophy. Magnetic resonance image brain showed abnormal high T2/fluid-attenuated inversion recovery signal within the dorsal brainstem and in the right globus pallidus with some reduced diffusivity. Despite recovery from the acute neurological and cardiac manifestations, he has ongoing deficits in his gross motor skills and continues to have hyperphagia with rapid weight gain (approx. 20 kg in 2 years). Ophthalmic findings are persistent. This case expands the phenotype associated with MTFMT disease.

Genotypic and phenotypic spectrum of infantile liver failure due to pathogenic TRMU variants.

PURPOSE: This study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and determine the role of cysteine supplementation in its treatment. METHODS: Individuals with biallelic (likely) pathogenic variants in TRMU were studied within an international retrospective collection of de-identified patient data. RESULTS: In 62 individuals, including 30 previously unreported cases, we described 47 (likely) pathogenic TRMU variants, of which 17 were novel, and 1 intragenic deletion. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow-up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals; 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency. CONCLUSION: In most patients, TRMU-associated ALF was a transient, reversible disease and cysteine supplementation improved survival.

Biochemical testing for inborn errors of metabolism: experience from a large tertiary neonatal centre.

Inborn errors of metabolism are an individually rare but collectively significant cause of mortality and morbidity in the neonatal period. They are identified by either newborn screening programmes or clinician-initiated targeted biochemical screening. This study examines the relative contribution of these two methods to the identification of inborn errors of metabolism and describes the incidence of these conditions in a large, tertiary, neonatal unit. We also examined which factors could impact the reliability of metabolic testing in this cohort. This is a retrospective, single-site study examining infants in whom a targeted metabolic investigation was performed from January 2018 to December 2020 inclusive. Data was also provided by the national newborn screening laboratory regarding newborn screening diagnoses. Two hundred and four newborns received a clinician-initiated metabolic screen during the time period examined with 5 newborns being diagnosed with an inborn error of metabolism (IEM) (2.4%). Of the 25,240 infants born in the hospital during the period examined, a further 11 newborns had an inborn error of metabolism diagnosed on newborn screening. This produced an incidence in our unit over the time described of 6.34 per 10,000 births. This number reflects a minimum estimate, given that the conditions diagnosed refer to early-onset disorders and distinctive categories of IEM only. Efficiency of the clinician-initiated metabolic screening process was also examined. The only statistically significant variable in requiring repeat metabolic screening was early day of life (z-score = - 2.58, p = 0.0098). A total of 28.4% was missing one of three key metabolic investigation parameters of blood glucose, ammonia or lactate concentration with ammonia the most common investigation missing. While hypoglycemia was the most common clinical rationale for a clinician-initiated metabolic test, it was a poor predictor of inborn error of metabolism with no newborns of 25 screened were diagnosed with a metabolic disorder. CONCLUSION: Clinician-targeted metabolic screening had a high diagnostic yield given the relatively low prevalence of inborn errors of metabolism in the general population. Thoughts should be given to the rationale behind each targeted metabolic test and what specific metabolic disease or category of inborn error of metabolism they are concerned along with commencing targeted testing. WHAT IS KNOWN: • Inborn errors of metabolism are a rare but potentially treatable cause of newborn mortality and morbidity. • A previous study conducted in a tertiary unit in an area with limited newborn screening demonstrated a diagnostic yield of 5.4%. WHAT IS NEW: • Clinician-initiated targeted metabolic screening has a good diagnostic performance even with a more expanded newborn screening programme. • Further optimisation could be achieved by examining the best timing and also the rationale of metabolic testing in the newborn period.

No effect of a musical intervention on stress response to venepuncture in a neonatal population.

AIM: To investigate the effect of a musical intervention on neonatal stress response to venepuncture as measured by salivary cortisol levels and pain profile scores. METHODS: In a randomised control crossover trial, participants were randomised to both a control arm (sucrose) and intervention arm (sucrose and music) for routine venepuncture procedures. Salivary swabs were collected at baseline, 20 minutes post-venepuncture and 4 hours post-venepuncture. Pain levels were assessed using the Premature Infant Pain Profile (PIPP). A total of 16 preterm neonates participated in both arms to complete the study. RESULTS: Cortisol values were elevated at all timepoints in the intervention arm (baseline, 20 minutes, and 4 hours post-procedure) but not significantly so (P = .056, P = .3, and P = .575, respectively). Median change in cortisol values from baseline was +128.48 pg/mL (-47.66 to 517.02) at 20 minutes and +393.52 pg/mL (47.88-1221.34) at 4 hours post-procedure in the control arm compared to -69.564 pg/mL (-860.96 to 397.289) and +100.48 pg/mL (-560.46 to 842.99) at 20 minutes and 4 hours post-procedure in the intervention arm. There was no statistically significant difference observed between groups (P = .311 at 20 minutes, and P = .203 at 4 hours post-procedure). PIPP scores were not significantly different between study arms. CONCLUSION: Our findings did not support the additional benefit of music intervention on neonatal stress response to venepuncture in preterm infants.

Percutaneous endoscopic gastrostomy for refractory epilepsy and medication refusal.

OBJECTIVE: Current guidelines for percutaneous endoscopic gastrostomy (PEG) placement focus largely on maintaining enteral feeding when oral feeding is no longer possible or adequate with an emphasis on nutrition and quality of life (QOL). Previous publications have also alluded to potential benefits in medication adherence, for example, in children with HIV, renal disease and neurodisability. We describe a cohort of children with refractory epilepsy who refused oral medication and in whom PEG tube placement was initiated for the purpose of drug administration. DESIGN: We identified children from the medical records of two tertiary paediatric units over a 9-year period who had PEG tube placement for administration of antiepileptic drug (AED) therapy and collected demographic and clinical details from chart reviews. We assessed parent-reported changes in seizure control and QOL using a structured questionnaire. RESULTS: Ten patients met the inclusion criteria. All families reported an improvement in ease of administering medications and eight reported a significant improvement in QOL. Nine children had a decrease in seizure frequency (lasting more than 12 months) following PEG tube placement, including two who underwent surgical intervention for their epilepsy during that period. Four had either a decrease in the number of drugs administered or their doses and four went on to receive fluids and nutrition through their tube on a regular basis. Seven reported PEG complications, which did not require removal of the PEG. CONCLUSIONS: This case series of children with resistant epilepsy demonstrates improvement in seizure control and QOL following PEG tube placement for AED administration.

A recurrent mitochondrial p.Trp22Arg NDUFB3 variant causes a distinctive facial appearance, short stature and a mild biochemical and clinical phenotype.

BACKGROUND: Isolated Complex I deficiency is the most common paediatric mitochondrial disease presentation, associated with poor prognosis and high mortality. Complex I comprises 44 structural subunits with at least 10 ancillary proteins; mutations in 29 of these have so far been associated with mitochondrial disease but there are limited genotype-phenotype correlations to guide clinicians to the correct genetic diagnosis. METHODS: Patients were analysed by whole-exome sequencing, targeted capture or candidate gene sequencing. Clinical phenotyping of affected individuals was performed. RESULTS: We identified a cohort of 10 patients from 8 families (7 families are of unrelated Irish ancestry) all of whom have short stature (<9th centile) and similar facial features including a prominent forehead, smooth philtrum and deep-set eyes associated with a recurrent homozygous c.64T>C, p.Trp22Arg NDUFB3 variant. Two sibs presented with primary short stature without obvious metabolic dysfunction. Analysis of skeletal muscle from three patients confirmed a defect in Complex I assembly. CONCLUSIONS: Our report highlights that the long-term prognosis related to the p.Trp22Arg NDUFB3 mutation can be good, even for some patients presenting in acute metabolic crisis with evidence of an isolated Complex I deficiency in muscle. Recognition of the distinctive facial features-particularly when associated with markers of mitochondrial dysfunction and/or Irish ancestry-should suggest screening for the p.Trp22Arg NDUFB3 mutation to establish a genetic diagnosis, circumventing the requirement of muscle biopsy to direct genetic investigations.