First pediatric organ donation after circulatory determination of death in Singapore: Facing challenges in the absence of a local practice guideline

Pediatric organ donation represents only a low proportion of overall organ donation in many parts of world, unable to match the needs for pediatric organ transplantation. Pediatric organ donation after circulatory determination of death (DCD) is increasingly explored in pediatric transplantation, as it increases the availability of organ grafts. A 6-year-old Caucasian boy with a history of arteriovenous malformation presented with a catastrophic intracranial bleed, resulting in severe brainstem dysfunction despite maximal medical and surgical measures. He did not fulfill the criteria for brain death, which must be met for pediatric organ donation in Singapore. Due to parental request, his organs were donated after withdrawal of life support and determination of death by circulatory criteria. Pediatric organ DCD poses many challenges in the pediatric population, especially in the absence of a local practice guideline. We present the first case of a pediatric organ DCD that has occurred in Singapore. Further work is needed, particularly in establishing a national policy for pediatric organ DCD and increasing overall awareness and acceptance toward pediatric organ donations.

Responsiveness of sphingosine phosphate lyase insufficiency syndrome to vitamin B6 cofactor supplementation

Sphingosine-1-phosphate (S1P) lyase is a vitamin B6-dependent enzyme that degrades sphingosine-1-phosphate in the final step of sphingolipid metabolism. In 2017, a new inherited disorder was described caused by mutations in SGPL1, which encodes sphingosine phosphate lyase (SPL). This condition is referred to as SPL insufficiency syndrome (SPLIS) or alternatively as nephrotic syndrome type 14 (NPHS14). Patients with SPLIS exhibit lymphopenia, nephrosis, adrenal insufficiency, and/or neurological defects. No targeted therapy for SPLIS has been reported. Vitamin B6 supplementation has therapeutic activity in some genetic diseases involving B6-dependent enzymes, a finding ascribed largely to the vitamin's chaperone function. We investigated whether B6 supplementation might have activity in SPLIS patients. We retrospectively monitored responses of disease biomarkers in patients supplemented with B6 and measured SPL activity and sphingolipids in B6-treated patient-derived fibroblasts. In two patients, disease biomarkers responded to B6 supplementation. S1P abundance and activity levels increased and sphingolipids decreased in response to B6. One responsive patient is homozygous for an SPL R222Q variant present in almost 30% of SPLIS patients. Molecular modeling suggests the variant distorts the dimer interface which could be overcome by cofactor supplementation. We demonstrate the first potential targeted therapy for SPLIS and suggest that 30% of SPLIS patients might respond to cofactor supplementation.

Novel LRPPRC Mutation in a Boy With Mild Leigh Syndrome, French-Canadian Type Outside of Québec

Background:

Leigh syndrome, French–Canadian type is unique to patients from a genetic isolate in the Saguenay–Lac-Saint-Jean region of Québec. It has also been recently described in 10 patients with LRPPRC mutation outside of Québec. It is an autosomal recessive genetic disorder with fatal metabolic crisis and severe neurological morbidity in infancy caused by LRPPRC mutation.

Methods and Results:

The authors report a boy with a novel LRPPRC compound heterozygous missense mutations c.3130C>T, c.3430C>T, and c.4078G>A found on whole-exome sequencing which correlated with isolated cytochrome c-oxidase deficiency found in skeletal muscle.

Conclusion:

LRPPRC mutation is a rare cause of cytochrome c-oxidase–deficient form of Leigh syndrome outside of Québec. Our patient broadens the spectrum of phenotypes of Leigh syndrome, French–Canadian type. LRPPRC mutation should be considered in children with early childhood neurodegenerative disorder, even in the absence of metabolic crisis. Early evaluation with whole-exome sequencing is useful for early diagnosis and for genetic counseling.

Enterovirus infections in Singaporean children: an assessment of neurological manifestations and clinical outcomes

INTRODUCTION

Enterovirus infections in childhood can be associated with significant neurological morbidity. This study aimed to describe the prevalence and range of neurological manifestations, determine the clinical characteristics and assess differences in clinical outcomes for Singaporean children diagnosed with enterovirus infections.

METHODS

In this single-centre, case-control study, clinical data was collected retrospectively from patients admitted to National University Hospital, Singapore, from August 2007 to October 2011 and diagnosed with enterovirus infection, based on the enterovirus polymerase chain reaction test, or cultures from throat and rectal swabs or cerebrospinal fluid samples. The occurrence of neurological manifestations was reviewed and clinical outcomes were assessed.

RESULTS

A total of 48 patients (age range: six days-17.8 years) were included in the study. Neurological manifestations were seen in 75.0% of patients, 63.9% of whom presented with aseptic meningitis. Other neurological manifestations included encephalitis, acute cerebellitis, transverse myelitis and autonomic dysfunction. The incidence of neurological manifestations was significantly higher in patients aged > 1 year as compared to younger patients (p = 0.043). In patients without neurological manifestations, a significantly higher proportion presented with hand, foot and mouth disease and poor feeding. Long-term neurological sequelae were seen in 16.7% of patients with neurological manifestations.

CONCLUSION

A wide spectrum of neurological manifestations resulting in a relatively low incidence of long-term neurological sequelae was observed in our study of Singaporean children with enterovirus infections. As some of these neurological morbidities were severe, careful evaluation of children with neurological involvement is therefore necessary.

SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome

Marinesco-Sjögren syndrome is a rare autosomal recessive multisystem disorder featuring cerebellar ataxia, early-onset cataracts, chronic myopathy, variable intellectual disability and delayed motor development. More recently, mutations in the SIL1 gene, which encodes an endoplasmic reticulum resident co-chaperone, were identified as the main cause of Marinesco-Sjögren syndrome. Here we describe the results of SIL1 mutation analysis in 62 patients presenting with early-onset ataxia, cataracts and myopathy or combinations of at least two of these. We obtained a mutation detection rate of 60% (15/25) among patients with the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts, myopathy) whereas the detection rate in the group of patients with more variable phenotypic presentation was below 3% (1/37). We report 16 unrelated families with a total of 19 different SIL1 mutations. Among these mutations are 15 previously unreported changes, including single- and multi-exon deletions. Based on data from our screening cohort and data compiled from the literature we found that SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy. Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants. Six patients with SIL1 mutations had no intellectual disability, extending the known wide range of cognitive capabilities in Marinesco-Sjögren syndrome to include normal intelligence. Modestly constant features were somatic growth retardation, skeletal abnormalities and pyramidal tract signs. Examination of mutant SIL1 expression in cultured patient lymphoblasts suggested that SIL1 mutations result in severely reduced SIL1 protein levels irrespective of the type and position of mutations. Our data broaden the SIL1 mutation spectrum and confirm that SIL1 is the major Marinesco-Sjögren syndrome gene. SIL1 patients usually present with the characteristic triad but cataracts might be missing in young children. As cognitive impairment is not obligatory, patients without intellectual disability but a Marinesco-Sjögren syndrome-compatible phenotype should receive SIL1 mutation analysis. Despite allelic heterogeneity and many families with private mutations, the phenotype related to SIL1 mutations is relatively homogenous. Based on SIL1 expression studies we speculate that this may arise from a uniform effect of different mutations on protein expression.

The cerebral vasculopathy of PHACES syndrome

BACKGROUND AND PURPOSE

PHACES syndrome is a neurocutaneous disorder of unknown etiology. We studied the spectrum of associated congenital and progressive cerebral vascular anomalies.

METHODS

The medical records of 7 patients with PHACES syndrome were reviewed and combined with an additional 108 PHACES cases identified from the literature. We reviewed the clinical characteristics, calculated the relative frequencies of each type of vascular anomaly, and assessed site of vessel involvement relative to hemangioma location.

RESULTS

Among a total of 115 PHACES cases, 89 (77.4%) had congenital and/or progressive cerebral vascular anomalies. The most commonly detected congenital arterial anomalies included dysplasia, aberrant origin or course, hypoplasia, and absence or agenesis. Arterial occlusions and stenoses were detected in 24 (20.9%) and 21 (18.3%) cases, respectively. Twenty (17.4%) had persistent embryonic arteries; 15 (13%) had saccular aneurysms. There appears to be a close relation between the regional distributions of cervicofacial hemangiomas and the locations of intracranial and extracranial vascular (and cardiac) anomalies.

CONCLUSIONS

The vasculopathy of PHACES chiefly comprises a spectrum of congenital and progressive large artery lesions. Based on known embryology and the relative frequencies of specific congenital vascular anomalies, we can predict that the initial cerebral vascular changes occur early in embryogenesis, by the fifth gestational week or earlier. There appears to be both a temporal and a regional link between the arterial anomalies of PHACES and the cutaneous infantile hemangioma.

Unusually mild phenotype of AADC deficiency in 2 siblings

Aromatic L-amino acid decarboxylase deficiency is a rare neurotransmitter defect leading to serotonin, dopamine and norepinephrine deficiency. Affected individuals usually present in infancy with severe developmental delay, oculogyric crises and extrapyramidal movements. We present the clinical, molecular and biochemical features of a pair of siblings who presented with fatigability, hypersomnolence and dystonia and who showed excellent response to treatment. Analysis of CSF biogenic amines, plasma AADC levels and direct sequencing of the DDC gene was performed. CSF catecholamine metabolites were reduced, with elevation of 3-O-methyldopa. Plasma AADC activity was undetectable in both siblings, and decreased in their carrier parents. One missense mutation (853C>T) was found in exon 8, and a donor splice site mutation was found in the intron after exon 6 (IVS6+4A>T). Both siblings showed excellent response to MAO inhibitor and dopamine agonist treatment. This report expands the clinical spectrum of AADC deficiency and contributes to the knowledge of the genotype and phenotype correlation for the DDC gene. It is important to recognize the milder phenotypes of the disease as these patients might respond well to therapy.

Decreased access to health care and social isolation among young adults with cerebral palsy after leaving school

OBJECTIVE

To examine if leaving special schools has a negative impact on the health care and social isolation of young adults with cerebral palsy.

METHODS

Young adults with cerebral palsy, aged between 15 and 22 years, were divided into 2 cohorts: current students, who were still receiving services from special schools, and school-leavers, who had since been discharged from care. A questionnaire and physical examination were administered to assess the extent of disability, health care received by, and social isolation of these young adults.

RESULTS

School-leavers had a greater degree of dissability than did students, although the results were not statistically significant. Health care exposure to specialists, general practitioners, therapists physiotherapists, occupational therapists, and/or speech therapists), and medical social workers decreased after leaving school; with the exception of contact with general practitioners, these results were significant (p<0.05). The entire cohort was more socially isolated than a control cohort. School-leavers participated in fewer activities outside their homes, but showed less concern about their disability than did current students.

CONCLUSIONS

Young adults with cerebral palsy continue to have health care and lifestyle needs after leaving school, which are currently not being adequately met.