An approach to recognising and identifying metabolic presentations in the paediatric Irish Traveller population.

The Irish Traveller population are an endogamous, traditionally nomadic, Irish population. Irish Travellers practice consanguinity in the majority of marriages, thus resulting in a higher rate of rare autosomal recessive conditions within the population due to homozygous variants. Herein, we outline the clinical phenotypes associated with metabolic conditions seen in this population presenting in the neonatal period, infancy and childhood. Although Irish Travellers are traditionally based in Ireland and the UK, there are populations also living in mainland Europe and the USA. While there is generally an understanding amongst Irish paediatricians of the recessive conditions seen with this population in Ireland, they may be less commonly encountered abroad. It is important to consider a non-genetic aetiology alongside any consideration for a metabolic disorder. CONCLUSION: This paper acts as a comprehensive review of the metabolic conditions seen and provides a guide for the investigation of an Irish Traveller child with a suspected metabolic condition. WHAT IS KNOWN: • The Irish Traveller population are an endogenous population. • There are higher rates of inherited metabolic conditions in this population compared to the general population in Ireland. WHAT IS NEW: • This paper is a comprehensive review of all known inherited metabolic conditions encountered in the Irish Traveller population.

Hyperammonaemia in Neonates and Young Children: Potential Metabolic Causes, Diagnostic Approaches and Clinical Consequences

Hyperammonaemia is a metabolic disturbance characterized by accumulation of ammonia in the blood. Entry of ammonia into the brain via the blood-brain barrier leads to hyperammonaemic encephalopathy. The causes of hyperammonaemia in paediatric patients vary. We present 3 cases of hyperammonaemia in critically ill children in whom an inborn metabolic disorder was identified and provide insights into the phenotypes, diagnostic approaches and management. In children with acute overwhelming illness and progressive neurological deterioration plasma ammonia measurement should be included in the urgent diagnostic work-up. We here raise the awareness that hyperammonaemia is a metabolic emergency requiring prompt recognition and treatment to avoid subsequent complications.

Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) in the Irish Paediatric Population.

Aim This study aims to investigate the disease frequency of Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) among the Irish population. Methods Children (<18 years) with MCADD were identified via the National Centre for Inherited Metabolic Disorders and the metabolic laboratory at Temple Street Children's University Hospital. Central Statistics Office population data was used to calculate epidemiological figures. Results From 1998 to 2016, 17 children (<18 years) were diagnosed with MCADD including two patients whose initial presentation was fatal. The mean age at initial presentation was 1.48 years (Range: 0.005 to 2.86). The incidence was 1:71650 with mortality at 15.38%. No child subsequently died post diagnosis. The common c.985A>G mutation accounted for 88% of alleles. Conclusion The incidence of MCADD in Ireland is lower than global estimates. The potential for under-ascertainment and late diagnosis of cases exists in Ireland and is of concern for a treatable condition with a significant mortality when undiagnosed. The authors welcome the introduction of MCADD to the National Newborn Bloodspot Screening Program.

Pregnancy management and outcome in patients with four different tetrahydrobiopterin disorders.

INTRODUCTION: Inborn errors of tetrahydrobiopterin (BH4) biosynthesis or recycling are a group of very rare neurometabolic diseases. Following growing awareness and improved availability of drug treatment the number of patients with BH4 disorders reaching adulthood is constantly increasing. Pregnancy care of patients with these disorders is therefore a new challenge for clinicians. METHODS: This retrospective study summarises for the first time clinical and biochemical monitoring data of 16 pregnancies in seven women with different disorders of BH4 metabolism and evaluates treatment regimens before and during pregnancy in relation to the obstetrical outcome and paediatric follow-up. RESULTS: Worsening of pre-existing neurological symptoms or occurrence of new symptoms during pregnancy was not observed in most of the cases. Treatment regimens remained mostly unchanged. Pregnancies were not complicated by disease-specific features. Organ abnormalities, miscarriage, prematurity, IUGR and chromosomal changes were occasionally reported, without showing any association with the standard drug treatment for BH4 deficiencies. CONCLUSION: Although our data on 16 pregnancies in seven patients did not present any association of standard drug treatment with an increased rate of pregnancy complications, abnormal obstetrical or paediatric outcome, an intensive clinical and biochemical supervision by a multidisciplinary team before, during and after the pregnancy in any BH4 deficiency is essential since available data on pregnancies in patients with BH4 deficiencies is limited.

Rotavirus Gastroenteritis is Associated with Increased Morbidity and Mortality in Children with Inherited Metabolic Disorders.

Rotavirus is the leading cause of infantile diarrhoea worldwide in children <5 years1. Although mortality rates are low in Ireland, certain populations are more susceptible to the associated morbidity and mortality of infection. A retrospective chart review of 14 patients with confirmed IMDs who were admitted to Temple Street Children's Hospital between 2010 to 2015 with rotavirus infection were compared with 14 randomly selected age matched controls. The median length of stay was 7 days (SD25.3) in IMD patients versus 1.5 days (SD 2.1) in the controls. IV fluids were required on average for 4.5 days (range 0-17) in IMD patients versus 0.63 days (range 0-3) in controls. This report highlights the increased morbidity of rotavirus infection in patients with IMD compared to healthy children. This vulnerable population are likely to benefit from the recent introduction of the rotavirus oral vaccination in October 2016.

A review of anaesthetic outcomes in patients with genetically confirmed mitochondrial disorders.

Mitochondrial disorders are a clinically and biochemically diverse group of disorders which may involve multiple organ systems. General anaesthesia (GA) poses a potential risk of decompensation in children with mitochondrial disorders, and there is little guidance for anaesthetists and other clinicians regarding the optimal anaesthetic agents and perioperative management to provide to patients with mitochondrial disease[15]. The aim of this review was to document adverse events and perioperative complications from GA in patients with genetically confirmed mitochondrial disorders. A retrospective chart review of patients with genetically confirmed mitochondrial disorders who had undergone GA was undertaken. The indication for GA, anaesthetic agents utilised, length of admission and post anaesthetic complications were documented and analysed. Twenty-six patients with genetically proven mitochondrial disease underwent 65 GAs. Thirty-four (52%), received propofol as their induction agent. Thirty-three (51%) patients received sevoflurane for the maintenance of anaesthesia, while 8 (12%) received isoflurane and 24 (37%) received propofol. The duration of most GAs was short with 57 (87%) lasting less than 1 h. Perioperative complications occurred in five patients while under GA including ST segment depression, hypotension and metabolic acidosis in one. All five patients were stabilised successfully and none required ICU admission as a consequence of their perioperative complications. The duration of hospital stay post GA was <24 h in 25 (38%) patients. CONCLUSION: No relationship between choice of anaesthetic agent and subsequent perioperative complication was observed. It is likely that individual optimisation on a case-by-case basis is more important overall than choice of any one particular technique. What is Known: • General anaesthesia (GA) poses a potential risk of decompensation in children with mitochondrial disorders. • There is a great diversity in the anaesthetic approaches undertaken in this cohort, and little guidance exists for anaesthetists and other clinicians regarding the optimal anaesthetic agents and perioperative management to provide to patients with mitochondrial disease. What is New: • In this study of 26 patients with genetically confirmed mitochondrial disease who underwent 65 GAs, no relationship between choice of anaesthetic agent and subsequent perioperative complication was observed • It is likely that individual optimisation on a case-by-case basis is more important overall than choice of any one particular technique.

Type 1 Tyrosinaemia.

Tyrosinaemia type 1 (TYR1, OMIM# 276700) is a rare autosomal recessive disease that results from an enzyme defect that leads to a deficiency in fumarylacetoacetase (FAH)1. We present 3 cases of TYR1 in the Irish population over a 9 year period, the only cases known to have been diagnosed in Ireland since 1989. The common presenting symptom was hypoglycaemia and the diagnosis was made by the identification of the pathognomonic biomarker succinylacetone on urine organic acid analysis. We discuss the clinical presentation, biochemical and genetic results including one novel mutation. We also highlight the importance of early initiation of Nitisinone (NTBC), which reduces the complications of TYR1 and the incidence of liver transplantation in this population2.

Clinical and genetic characterisation of infantile liver failure syndrome type 1, due to recessive mutations in LARS.

BACKGROUND: Recessive LARS mutations were recently reported to cause a novel syndrome, infantile liver failure syndrome type 1 (ILFS1), in six Irish Travellers. We have since identified four additional patients, including one of Ashkenazi origin, representing the largest ILFS1 cohort to date. Our study aims to define the ILFS1 clinical phenotype to help guide diagnosis and patient management. METHODS: We clinically evaluated and reviewed the medical records of ten ILFS1 patients. Clinical features, histopathology and natural histories were compared and patient management strategies reviewed. RESULTS: Early failure to thrive, recurrent liver dysfunction, anemia, hypoalbuminemia and seizures were present in all patients. Most patients (90 %) had developmental delay. Encephalopathic episodes triggered by febrile illness have occurred in 80 % and were fatal in two children. Two patients are currently >28 years old and clinically well. Leucine supplementation had no appreciable impact on patient well-being. However, we suggest that the traditional management of reducing/stopping protein intake in patients with metabolic hepatopathies may not be appropriate for ILFS1. We currently recommend ensuring sufficient natural protein intake when unwell. CONCLUSIONS: We report the first non-Irish ILFS1 patient, suggesting ILFS1 may be more extensive than anticipated. Low birth weight, early failure to thrive, anemia and hypoalbuminemia are amongst the first presenting features, with liver dysfunction before age 1. Episodic hepatic dysfunction is typically triggered by febrile illness, and becomes less severe with increasing age. While difficult to anticipate, two patients are currently >28 years old, suggesting that survival beyond childhood may be associated with a favourable long-term prognosis.

'Malignant Phenylketonuria' (PKU) Due to Dihydropteridine Reductase (DHPR) Deficiency.

DHPR deficiency is a rare autosomal recessively inherited metabolic disorder of tetrahydrobiopterin (BH4) regeneration. Clinical symptoms may comprise microcephaly, developmental delay, ataxia and seizures. BH4 is the cofactor for the enzyme phenylalanine (Phe)hydroxylase (PAH), and for tryptophan and tyrosine hydroxylases, both of which are essential for serotonin and dopamine biosynthesis. We present four patients in two families who are being treated at the National Centre for Inherited Metabolic Disorders (NCIMD). All are members of the Irish Traveller population. We have identified a homozygous mutation, c.353C>T, in the DHPR (QDPR) gene which, to the best of our knowledge, has not been previously described. The mainstay of treatment is a life-long Phe-restricted diet together with supplementation of L-dopa and 5-hydroxy tryptophan (5-HT) and folinic acid. In Ireland, there is neurological comorbidity in our adult DHPR patients, although the overall outcome is satisfactory and one affected female has three healthy children.

Parental experience of enzyme replacement therapy for Hunter syndrome.

We aimed to establish the profile of Irish patients with Hunter Syndrome (Mucopolysaccharidosis type II, MPS II) receiving weekly intravenous Enzyme Replacement Therapy (ERT) with recombinant iduronate-2-sulfatase and to assess the social impact and parental opinion of ERT through the use of a parental questionnaire. Nine patients aged 3.5- 14 years have received a mean of 2 (range 0.5-3.5) years of ERT. Treatment was associated with clinical improvements from baseline in hepatosplenomegaly in 6/7 (85%) respiratory manifestations in 4/6 (67%) and a mean reduction in urinary glycosaminoglycan excretion of 62%. Changes noted by parents included increased energy 3/9 (33%) and softening of skin, hair and facial features 8/9 (89%). Parents report that seven hours weekly were spent on hospitalizations for ERT. Parental employment was adversely affected in 8 (89%) families. One day of school/preschool (20%) was lost every week for 8 (89%) children. All parents believed the benefits of ERT out-weigh the difficulties involved. All families would welcome the introduction of home based therapy. In conclusion the social and educational burden of hospital-based ERT on these children and their families is significant. The introduction of home-based therapy is likely to improve overall quality of life for MPSII patients and their families.

Classical Galactosaemia in Ireland: incidence, complications and outcomes of treatment.

Newborn screening for the inborn error of metabolism, classical galactosaemia prevents life-threatening complications in the neonatal period. It does not however influence the development of long-term complications and the complex pathophysiology of this rare disease remains poorly understood. The objective of this study was to report the development of a healthcare database (using Distiller Version 2.1) to review the epidemiology of classical galactosaemia in Ireland since initiation of newborn screening in 1972 and the long-term clinical outcomes of all patients attending the National Centre for Inherited Metabolic Disorders (NCIMD). Since 1982, the average live birth incidence rate of classical galactosaemia in the total Irish population was approximately 1:16,476 births. This reflects a high incidence in the Irish 'Traveller' population, with an estimated birth incidence of 1:33,917 in the non-Traveller Irish population. Despite early initiation of treatment (dietary galactose restriction), the long-term outcomes of classical galactosaemia in the Irish patient population are poor; 30.6 % of patients ≥ 6 yrs have IQs <70, 49.6 % of patients ≥ 2.5 yrs have speech or language impairments and 91.2 % of females ≥ 13 yrs suffer from hypergonadotrophic hypogonadism (HH) possibly leading to decreased fertility. These findings are consistent with the international experience. This emphasizes the requirement for continued clinical research in this complex disorder.

Should children with inherited metabolic disorders receive varicella vaccination?

The aim was to determine the rate of varicella infection and complications in children with disorders of intermediary metabolism (IEM) between the ages of 1 and 16 years attending our national metabolic referral centre. Of 126 children identified, a response was received from 122. A history of previous varicella infection was identified in 64 cases (53%) and of varicella vaccination in 5 (4%). Fifty-three (43%) patients apparently did not have a history of clinical varicella infection. Of the 64 children with a history of varicella infection, five required hospitalisation for complications, including life-threatening lactic acidosis in one patient with mitochondrial disease and metabolic decompensation in four patients. In conclusion, varicella infection may cause an increased risk of metabolic decompensation in patients with IEMs. We propose that a trial of varicella vaccination be considered for this cohort of patients with monitoring of its safety and efficacy.

Long chain fatty acid oxidation defects in children: importance of detection and treatment options.

BACKGROUND: Mitochondrial beta oxidation plays a major role in energy production. Long chain fatty acid oxidation defects include deficiency of the trifunctional protein (rare) or more commonly defects of the long chain 3-hydroxy acyl-CoA dehydrogenase enzyme (LCHAD). These long chain defects have variable presentations, they may present in the neonate or infant with sudden death, hepatopathy (Reyes disease), hypoketotic hypoglycaemia, rhabdomyolysis, myopathy, cardiomyopathy and with late complications such as peripheral neuropathy, pigmentary retinopathy, retinal degeneration and progressive visual loss. The correct diagnosis at presentation is not only life saving but also allows for the appropriate dietary and other intervention, which may have major effects on outcome. AIM: Three case reports of patients with long chain fatty acid oxidation defects who have shown significant benefits from treatment are reported. CONCLUSIONS: These paediatric presentations illustrate the clinical heterogeneity of long chain fatty acid oxidation defects and opportunities for effective management if correctly diagnosed.

Mitochondrial cytopathies, phenotypic heterogeneity and a high incidence.

Mitochondrial respiratory chain disorders account for significant and varied presentations in paediatric practice. The true prevalence of these disorders in the paediatric population is still not well documented with predicted geographic variation. We report a retrospective analysis over a seven year period of cases presenting to a tertiary care centre and associated clinical features. The overall prevalence of mitochondrial disorders in our population is higher than expected (1/9,000 births), explained in part by multiple presentations in a consanguineous subgroup of the population (Irish travellers).

Glutaric aciduria type I: outcome in the Republic of Ireland.

Twenty-one patients have been diagnosed with glutaric aciduria type I over a 16-year period in the Republic of Ireland, 11 following clinical presentation and 10 following a high-risk screen. Nineteen have been managed with diet. Eight patients have died, of whom 7 were diagnosed clinically. Six had dystonic and one spastic cerebral palsy. Of the 11 patients who did not have cerebral palsy, 10 were diagnosed following a high-risk screen. Seven of the 11 have no abnormal neurological signs; 6 of the 7 have abnormal CT or MRI findings; and no case of striatal degeneration has occurred during the past 14 years in the high-risk screened group.

Fatal presentation of ornithine transcarbamylase deficiency in a 62-year-old man and family studies.

Ornithine transcarbamylase deficiency (OTCD) resulting from deficiency of the mitochondrial enzyme OTC shows extensive phenotypic heterogeneity influenced by allelic heterogeneity and modifying environmental influences such as protein intake. We report the fatal late-onset presentation of OTCD in a 62-year-old man with the V337L mutation, a previous presentation in his grandson and negative clinical and biochemical screening of the proband's three daughters.

Ocular findings in glutaric aciduria type 1.

PURPOSE: To determine the nature and course of ocular abnormalities in glutaric aciduria (acidemia) type 1 (GA1). METHODS: Fifteen children with GA1 have been studied in the Republic of Ireland. A retrospective review of the records of the 6 children who died during their illness and prospective clinical examination of 9 survivors were performed. RESULTS: Seven of the 15 children had abnormal eye findings. Ocular complications included intraretinal hemorrhages, cataract, gaze palsy, strabismus, ametropia, and pigmentary retinopathy. CONCLUSION: Ocular involvement is common in glutaric aciduria. Complete ophthalmologic evaluation is recommended in all patients suspected to have this rare disease. Intraretinal hemorrhages due to GA1 could be misinterpreted as resulting from child abuse, and it is important to include this disorder with the differential diagnosis of child abuse.

Prevention of cerebral palsy in glutaric aciduria type 1 by dietary management.

AIMS: To study retrospectively the effects of treatment and the clinical outcome in 12 patients with glutaric aciduria type 1; and to compare the outcome in 6 patients diagnosed as a result of family screening with 6 patients who were diagnosed late after symptomatic presentation. SETTING: The National Centre for Inherited Metabolic Disorders, The Children's Hospital, Dublin, Ireland. RESULT: Four of the 6 children detected on screening are developmentally normal, 1 died, and the remaining 1 has mild mental handicap. All 6 of the late diagnosed symptomatic group suffered dyskinetic cerebral palsy and 5 have died. CONCLUSION: Experience of 50 patient treatment years has shown that early intensive management can alter the natural history of this rare disorder.