Patient Care Standards for Primary Mitochondrial Disease in Australia. An Australian adaptation of the Mitochondrial Medicine Society recommendations

Leber Hereditary Optic Neuropathy: Support, Genetic Prediction and Accurate Genetic Counselling Enhance Family Planning Choices

With the increased availability of genetic testing and the addition of mitochondrial genetic variants on disease panels, accurate genetic counselling for individuals and families affected by, or at risk of, Leber hereditary optic neuropathy (LHON) is becoming increasingly relevant. Challenges in providing genetic counselling for LHON include its mitochondrial inheritance pattern, different haplogroups, incomplete penetrance and that it predominantly affects males. Accurate genetic counselling aims to avoid incorrect disease-risk assessment and delays in either diagnosis or implementation of psychosocial support. Families are also empowered to make autonomous health decisions regarding potential trigger factors for LHON vision loss and informed reproductive choices. Using clinical vignettes, this review demonstrates that an increased awareness of LHON amongst eye care, general and genetic health professionals can address challenges and misconceptions.

Current global vitamin and cofactor prescribing practices for primary mitochondrial diseases: Results of a European reference network survey

Primary mitochondrial diseases (PMD) account for a group of approximately 400 different genetic disorders with diverse clinical presentations and pathomechanisms. Although each individual disorder is rare, collectively they represent one of the largest groups in the field of inherited metabolic disorders. The complexity of PMD results in a continued lack of therapeutic options, necessitating a predominantly symptomatic treatment approach for affected patients. While a subset of diseases responds exceptionally well to treatment with specific vitamins or cofactors, for most PMD systematic reviews were not able to show significant benefit. This is in discrepancy to their continued frequent use among specialists. To gain further insight into the current clinical practice of vitamin and cofactor supplementation among clinicians treating children and adults affected by PMD, we conducted a worldwide cross-sectional questionnaire study exploring the choice of substances and the specific diseases where they are applied. To our knowledge, this is the first global study exploring this topic and featuring a high response rate from paediatricians. The vast majority (95%, 106/112) of responding specialists recommended the use of vitamins and cofactors, either in an agnostic approach irrespective of the specific PMD or directed to the treatment of specific diseases or phenotypes. Our study highlights significant regional and specialty-specific differences in supplementation practices. We provide some preliminary insights into specialist-based opinions regarding the use of vitamins and cofactors in PMD and highlight the need for more rigorous clinical and preclinical investigations and/or clear consensus statements.

Cascade testing in mitochondrial diseases: a cross-sectional retrospective study

BACKGROUND

Cascade testing can offer improved surveillance and timely introduction of clinical management for the at-risk biological relatives. Data on cascade testing and costs in mitochondrial diseases are lacking. To address this gap, we performed a cross-sectional retrospective study to provide a framework for cascade testing in mitochondrial diseases, to estimate the eligibility versus real-time uptake of cascade testing and to evaluate the cost of the genetic diagnosis of index cases and the cost of predictive cascade testing.

METHODS

Data was collected through retrospective chart review. The variant inheritance pattern guided the identification of eligible first-degree relatives: (i) Males with mitochondrial DNA (mtDNA) single nucleotide variants (SNVs) - siblings and mothers. (ii) Females with mtDNA SNVs - siblings, mothers and offspring. (iii) Autosomal Dominant (AD) nuclear DNA (nDNA) variants - siblings, offspring and both parents. (iv) Autosomal Recessive (AR) nDNA variants - siblings.

RESULTS

We recruited 99 participants from the Adult Mitochondrial Disease Clinic in Sydney. The uptake of cascade testing was 55.2% in the mtDNA group, 55.8% in the AD nDNA group and 0% in AR nDNA group. Of the relatives in mtDNA group who underwent cascade testing, 65.4% were symptomatic, 20.5% were oligosymptomatic and 14.1% were asymptomatic. The mean cost of cascade testing for eligible first-degree relatives (mtDNA group: $694.7; AD nDNA group: $899.1) was lower than the corresponding index case (mtDNA group: $4578.4; AD nDNA group: $5715.1) (p < 0.001).

CONCLUSION

The demand for cascade testing in mitochondrial diseases varies according to the genotype and inheritance pattern. The real-time uptake of cascade testing can be influenced by multiple factors. Early diagnosis of at-risk biological relatives of index cases through cascade testing, confirms the diagnosis in those who are symptomatic and facilitates implementation of surveillance strategies and clinical care at an early stage of the disease.

Pregnancy in women with mitochondrial disease-A literature review and suggested guidance for preconception and pregnancy care

Mitochondrial donation to reduce the risk of primary mitochondrial disease transmission from mother to child is now permitted under Australian law as part of a clinical trial. The energy demands of pregnancy have the potential to worsen mitochondrial disease symptoms and severity in affected women. We conducted a systematic literature review on mitochondrial disease in pregnancy; five cohort studies and 19 case reports were included. For many women with mitochondrial disease, pregnancy does not have a negative effect on health status. However, serious adverse outcomes may occur. We provide suggested guidelines for preconception counselling and antenatal care.

Administration of bicarbonates through percutaneous gastrostomy with continuous nocturnal infusion in a patient with Kearns-Sayre disease: a life changing therapeutical paradigm

BACKGROUND

Mitochondrial diseases (MDs) are systemic disorders that can affect multiple organs. Renal manifestations, including renal tubular acidosis, are common because kidneys are particularly vulnerable to energy deprivation. Treatment of MDs is often complex and electrolyte replacement can be difficult especially in pediatric patients, because large and repeated amounts of oral supplements are needed but are not well tolerated.

CASE PRESENTATION

We describe the case of a girl affected by Kearns-Sayre disease with severe renal tubular acidosis. The management of her metabolic acidosis was challenging because she showed persistent low levels of serum bicarbonates despite a progressive incrementation of oral bicarbonates. Furthermore, as a result to the ingestion of large amounts of alkali, the girl developed an aversion to oral supplementation. After positioning a percutaneous gastrostomy (PEG) and starting enteral administration of bicarbonates (with daily boluses and continuous nocturnal infusion), she finally obtained an adequate electrolyte control, with a significant increase in her quality of life.

CONCLUSIONS

In MDs, the combination of nocturnal continuous enteral administration of alkali plus diurnal boluses may represent a valid solution to correct metabolic acidosis. It can also result in an improved patients' quality of life, particularly in pediatric settings, where compliance to oral therapy is often lacking due to the large and repeated amounts of unpalatable bicarbonates solutions required.

Healthcare resource utilization of patients with mitochondrial disease in an outpatient hospital setting

BACKGROUND AND OBJECTIVES

Mitochondrial diseases present as multi-system disorders requiring a comprehensive multidisciplinary approach. The data on healthcare resource utilization associated with mitochondrial diseases and the clinical drivers of these costs are limited including for the out-patient setting where the majority of the clinical care for mitochondrial disease patients occurs. We performed a cross-sectional retrospective study of out-patient healthcare resource utilization and costs for patients with a confirmed diagnosis of mitochondrial disease.

METHODS

We recruited participants from the Mitochondrial Disease Clinic in Sydney and stratified them into three groups: those with mitochondrial DNA (mtDNA) mutations (Group 1), those with nuclear DNA (nDNA) mutations and the predominant phenotype of chronic progressive external ophthalmoplegia (CPEO) or optic atrophy (Group 2) and those without a confirmed genetic diagnosis but clinical criteria and muscle biopsy findings supportive of a diagnosis of mitochondrial disease (Group 3). Data was collected through retrospective chart review and out-patient costs were calculated using the Medicare Benefits Schedule.

RESULTS

We analyzed the data from 91 participants and found that Group 1 had the greatest average out-patient costs per person per annum ($838.02; SD 809.72). Neurological investigations were the largest driver of outpatient healthcare costs in all groups (average costs per person per annum:-Group 1: $364.11; SD 340.93, Group 2: $247.83; SD 113.86 and Group 3: $239.57; SD 145.69) consistent with the high frequency (94.5%) of neurological symptoms. Gastroenterological and cardiac-related out-patient costs were also major contributors to out-patient healthcare resource utilization in Groups 1 and 3. In Group 2, ophthalmology was the second-most resource intensive specialty ($136.85; SD 173.35). The Group 3 had the greatest average healthcare resource utilization per person over the entire duration of out-patient clinic care ($5815.86; SD 3520.40) most likely due to the lack of a molecular diagnosis and a less customized management approach.

CONCLUSION

The drivers of healthcare resource utilization are dependent on the phenotype-genotype characteristics. Neurological, cardiac, and gastroenterological costs were the top three drivers in the out-patient clinics unless the patient had nDNA mutations with predominant phenotype of CPEO and/or optic atrophy wherein ophthalmological-related costs were the second most resource intensive driver.

L-arginine in Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes: A Systematic Review

Background and Objectives

Stroke management in the context of primary mitochondrial disease is clinically challenging, and the best treatment options for patients with stroke-like episodes remain uncertain. We sought to perform a systematic review of the safety and efficacy of l-arginine use in the acute and prophylactic management of stroke-like episodes in patients with mitochondrial disease.

Methods

The systematic review was registered in PROSPERO (CRD42020181230). We searched 6 databases from inception to January 15, 2021: MEDLINE, Embase, Scopus, Web of Science, CINAHL, and ClinicalTrials.gov. Original articles and registered trials available, in English, reporting l-arginine use in the acute or prophylactic management of stroke-like episodes in patients with genetically confirmed mitochondrial disease were eligible for inclusion. Data on safety and treatment response were extracted and summarized by multiple observers. Risk of bias was assessed by the methodologic quality of case reports, case series, and a risk-of-bias checklist for nonrandomized studies. Quality of evidence was synthesized with the Oxford Centre for Evidence-Based Medicine Levels of Evidence and Grade of Recommendations. The predetermined main outcome measures were clinical response to l-arginine treatment, adverse events, withdrawals, and deaths (on treatment and/or during follow-up), as defined by the author.

Results

Thirty-seven articles met inclusion criteria (0 randomized controlled trials; 3 open-label; 1 retrospective cohort; 33 case reports/case series) (N = 91 patients; 86% m.3243A>G). In the case reports, 54% of patients reported a positive clinical response to acute l-arginine, of which 40% were concomitantly treated with antiepileptic drugs. Improved headache at 24 hours was the greatest reported benefit in response to IV l-arginine in the open-label trials (31 of 39, 79%). In 15 of 48 patients (31%) who positively responded to prophylactic l-arginine, antiepileptic drugs were either used (7 of 15) or unreported (8 of 15). Moderate adverse events were reported in the follow-up of both IV and oral l-arginine treatment, and 11 patients (12%) died during follow-up or while on prophylactic treatment.

Discussion

The available evidence is of poor methodologic quality and classified as Level 5. IV and oral l-arginine confers no demonstrable clinical benefit in either the acute or prophylactic treatment of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes, with more robust controlled trials required to assess its efficacy and safety profile.