The peroxisomal disorder spectrum and Heimler syndrome: Deep phenotyping and review of the literature.

The spectrum of peroxisomal disorders is wide and comprises individuals that die in the first year of life, as well as people with sensorineural hearing loss, retinal dystrophy and amelogenesis imperfecta. In this article, we describe three patients; two diagnosed with Heimler syndrome and a third one with a mild-intermediate phenotype. We arrived at these diagnoses by conducting complete ophthalmic (National Eye Institute), auditory (National Institute of Deafness and Other Communication Disorders), and dental (National Institute of Dental and Craniofacial Research) evaluations, as well as laboratory and genetic testing. Retinal degeneration with macular cystic changes, amelogenesis imperfecta, and sensorineural hearing loss were features shared by the three patients. Patients A and C had pathogenic variants in PEX1 and Patient B, in PEX6. Besides analyzing these cases, we review the literature regarding mild peroxisomal disorders, their pathophysiology, genetics, differential diagnosis, diagnostic methods, and management. We suggest that peroxisomal disorders are considered in every child with sensorineural hearing loss and retinal degeneration. These patients should have a dental evaluation to rule out amelogenesis imperfecta as well as audiologic examination and laboratory testing including peroxisomal biomarkers and genetic testing. Appropriate diagnosis can lead to better genetic counseling and management of the associated comorbidities.

Peroxisomal Disorders and Retinal Degeneration.

Peroxisomal disorders are a group of inherited metabolic diseases, which can be incompatible with life in the postnatal period or allow survival into adulthood. Retinopathy is a recurrent feature in both the severely and mildly affected patients, which can be accompanied with other ophthalmological pathologies. Thanks to next-generation sequencing, patients originally identified with other inherited blinding diseases were reclassified as suffering from peroxisomal disorders. In addition, new peroxisomal gene defects or disease presentations exhibiting retinal degeneration were recently identified. The pathogenic mechanisms underlying retinopathy in peroxisomal disorders remain unresolved.

Visual loss as first clinical manifestation of X-linked adrenoleukodystrophy / Perda visual como primeira manifestação clínica de adrenoleucodistrofia ligada ao X

Abstract X-linked adrenoleukodystrophy (X-ALD) represents a group of diseases characterized by the accumulation of very long chain fattyacids (VLCFAs) in the tissues. Its clinical manifestations are usually manifold. Visual changes may be present, but they often appear later in the disease. We describe here the case of a 9-year-old boy with X-ALD, whose first symptom was visual loss, which began at 8 years of age. His ophthalmologic evaluation revealed no alterations. Shortly thereafter, he suffered a head injury. The magnetic resonance imaging of brain revealed findings that led to the suspicion of X-ALD. The plasma VLCFA dosage confirmed this diagnosis. This report aims toshow that in cases of visual loss with a normal ophthalmic examination, a high index of suspicion should be given for conditions suchas X-ALD, since it affects the cortical routes related to vision. Fundoscopy findings appear late in X-ALD.

Resumo A adrenoleucodistrofia ligada ao X (X-ALD) representa um grupo de doenças caracterizadas pelo acúmulo de ácidos graxos de cadeia muito longa (VLCFAs) nos tecidos. Suas manifestações clínicas costumam ser múltiplas. Alterações visuais podem estar presentes, contudo costumam surgir mais tardiamente na doença. Descrevemos aqui o caso de um menino de 9 anos com X-ALD, cujo primeiro sintoma foi perda visual, iniciada aos 8 anos de idade. A sua avaliação oftalmológica não revelou alterações. Pouco tempo depois, ele sofreu um traumatismo craniano. A imagem de ressonância magnética de encéfalo revelou achados que levaram a suspeita de X-ALD. A dosagem dos VLCFAs no plasma confirmou este diagnóstico. Este relato tem como objetivo mostrar que em casos de perda visual com um exame oftalmológico normal, deve-se ter um alto índice de suspeita para condições como a X-ALD, pois a mesma afeta as vias corticais relacionadas à visão. Nessa doença, os achados da fundoscopia aparecem mais tardiamente.

Novel retinal findings in peroxisomal biogenesis disorders.

Peroxisomal biogenesis disorders are caused by disruption of long chain fatty acid metabolism due to mutations in PEX genes. Individuals with these disorders often have vision loss due to optic atrophy and pigmentary retinopathy. We report an unusual retinal manifestation of peroxisomal biogenesis disorder.

Anesthesia in a child with suspected peroxisomal disorder.

We present the case of an 8­year-old female child with suspected peroxisomal disorder requiring general anesthesia for adenotomy, paracentesis and brainstem-evoked response audiometry. Peroxisomes are small intracellular organelles that catalyse key metabolic reactions. Peroxisomal disorders are a heterogeneous group of rare genetic diseases. Anesthesia can be challenging as adrenal insufficiency, mental retardation, muscle weakness, risk of pulmonary aspiration, airway complications, seizure disorders and altered pharmacokinetics and pharmacodynamics can occur in these patients but guidelines for anesthesia do not exist due to the heterogeneity and rarity of these diseases and case reports are rare. Anesthesia was induced by sevoflurane via a face mask, followed by remifentanil and rocuronium for oral intubation after intravenous access was obtained. Anesthesia was maintained with sevoflurane and remifentanil. Dexamethasone was given for prophylaxis of postoperative nausea and vomiting as well as perioperative adrenal crises. Piritramide was given for postoperative analgesia. With this approach anesthesia was uneventful. The trachea was extubated with the patient awake and she was taken to the recovery room in a stable condition. The classification and breadth of clinical manifestations of peroxisomal disorders is complex and briefly summarized. Anesthesiologists should consider characteristics of their particular patient's form of peroxisomal disorder, as this may greatly influence procedural planning.

Ataxic form of autosomal recessive PEX10-related peroxisome biogenesis disorders with a novel compound heterozygous gene mutation and characteristic clinical phenotype.

Peroxisome biogenesis factor 10 (PEX10) is involved in the import of peroxisomal matrix proteins, and the mutation of this gene causes 3 subtypes of peroxisome biogenesis disorders, namely Zellweger syndrome (severe), neonatal adrenoleukodystrophy (moderate) and an ataxic form (mild). Here, we report 3 siblings of the ataxic form with cerebellar ataxia, mild mental retardation, and 3 additional characteristic features: mydriasis, hyperreflexia and involuntary head movement. All 3 siblings are compound heterozygous for a previously reported mutation, c.2T>C (p.M1T), and a novel mutation, c.920G>A, causing a missense change (p.C307Y) located in the RING finger domain of PEX10. The present cases suggest that these PEX10 mutations involve not only cerebellar but also more multiple nervous systems including pupillary autonomic, pyramidal and extrapyramidal systems.

Effect of l-Arginine in One Patient with Peroxisome Biogenesis Disorder due to PEX12 Deficiency.

Peroxisome biogenesis disorders (PBD) are a heterogeneous group of disorders due to PEX genes mutations, with a broad clinical spectrum comprising severe neonatal disease to mild presentation. Recently, Berendse et al reported an improvement of peroxisomal functions with l-arginine supplementation in fibroblasts with specific mutations of PEX1, PEX6, and PEX12. We report the first treatment by l-arginine in a patient homozygous for the specific PEX12 mutation shown to be l-arginine responsive in fibroblasts. We described the effect of l-arginine on biochemical (decrease of some plasma peroxisomal parameters) and neurophysiological (improvement of deafness) parameters. Some subjective clinical effects have also been observed (no more sialorrhea, behavior improvement). More studies are needed to assess the efficacy of l-arginine in some PBD patients with specific mutations.

Systemic diseases associated with retinal dystrophies.

Inherited retinal degeneration (IRD) may occur in isolation or as part of a multi-systemic condition. Ocular manifestations may be the presenting symptom of a syndromic disease and can include retinitis pigmentosa, cone-rod dystrophy, or maculopathy. Alternatively, patients affected with syndromic disease may already have other systemic manifestations at the time retinal disease is diagnosed. Some of these systemic diseases can cause significant morbidity. Here, we review several of these syndromic IRDs and their underlying genetic causes. Early recognition and referral for systemic evaluation and surveillance may lead to early intervention and an improved outcome. Obtaining a molecular diagnosis can be beneficial in securing a definitive diagnosis, especially in cases with atypical presentations. A genetic diagnosis may also be informative with regard to prognosis and potential therapies. Effective management and rehabilitation for patients with syndromic retinal dystrophy requires a comprehensive genetic-based team approach involving patients, family members, ophthalmologists, primary care physicians, and geneticists.

Peroxisomal disorders with infantile seizures.

Peroxisomes are organelles responsible for multiple metabolic pathways including the biosynthesis of plasmalogens and the oxidation of branched-chain as well as very-long-chain fatty acids (VLCFAs). Peroxisomal disorders (PDs) are heterogeneous groups of diseases and affect many organs with varying degrees of involvement. Even pathogenetically distinct PDs share some common symptoms. However, several PDs have uniquely characteristic clinical findings. The durations of survival in PDs are also variable. Infants with PDs are usually presented with developmental delay, visual and hearing impairment. Generalized hypotonia is present in severe cases. Epileptic seizures are also a common characteristic of patients with certain PDs. Nonetheless, the classification and evolution of epilepsy in PDs have not been elucidated in detail. Here, we review the relevant literatures and provide an overview of PDs with particular emphasis on the characteristics of seizures in infants.

Peroxisomal disorder-unusual presentation as failure to thrive in early infancy.

Failure to thrive is not uncommon in paediatric practice and often leads to multiple investigations to find the underlying cause. We report an infant who presented mainly with mild dysmorphism, failure to thrive and elevated alanine transferase (ALT) in early infancy. She was diagnosed to have a peroxisomal biogenesis disorder on further investigation. Peroxisomal disorders represent a spectrum of conditions with absent or abnormal function of intra-cytoplasmic organelles called peroxisomes. Clinical presentation is quite varied, depending on both the type and severity. We describe the clinical presentation of this case, followed by a brief discussion on peroxisomal disorders.

Essential fatty acid profiling for routine nutritional assessment unmasks adrenoleukodystrophy in an infant with isovaleric acidaemia.

We report a 16-month-old asymptomatic male with enzyme confirmed isovaleric acidaemia (IVA; isovaleryl-CoA dehydrogenase deficiency; OMIM 243500) who, upon routine nutritional follow-up, presented evidence of peroxisomal dysfunction. The newborn screen (2 days of life) revealed elevated C(5)-carnitine (2.95 µmol/L; cutoff <0.09 µmol/L) and IVA was subsequently confirmed by metabolic profiling and in vitro enzymology. Plasma essential fatty acid (EFA) analysis, assessed to evaluate nutritional status during protein restriction and L: -carnitine supplementation, revealed elevated C(26:0) (5.0 µmol/L; normal <1.3). Subsequently, metabolic profiling and molecular genetic analysis confirmed X-linked adrenoleukodystrophy (XALD). Identification of co-inherited XALD with IVA in this currently asymptomatic patient holds significant treatment ramifications for the proband prior to the onset of neurological sequelae, and critically important counselling implications for this family.

Neonatal adrenoleukodystrophy presenting with seizure at birth: a case report and review of the literature.

Neonatal seizures are critical conditions because they are usually related to significant illnesses that require a specific therapy. Antepartum and peripartum seizures are very rare, and represent signs of prenatal-onset neurologic dysfunction. A review of the literature revealed that the main etiologies include severe brain malformations, multiple anomalies, and metabolic encephalopathy. A high incidence of early fatality and serious neurologic sequelae were noted. To our knowledge, this is the first case report of neonatal adrenoleukodystrophy presenting with seizure at birth. These very-early-onset seizures may require unique diagnostic and therapeutic considerations, in contrast with the later onset of seizures in neonates.

Molecular and neurologic findings of peroxisome biogenesis disorders.

Peroxisomal disorders, an expanding group of genetic disorders in humans, can be grouped into three categories: peroxisome biogenesis disorders, single peroxisomal enzyme deficiencies, and contiguous gene syndrome. At present, 13 complementation groups of peroxisome biogenesis disorders and their responsible genes have been identified, including our newly identified group with a PEX14 defect. We describe neuronal abnormalities related to deficiencies in peroxisomes and the phenotype-genotype relationship in peroxisome biogenesis disorders. We also identified 32 Japanese patients with peroxisome biogenesis disorders, subdivided into six complementation groups. Our institution acts as the only diagnostic center for studies on peroxisomal disorders in Japan.

Optico-cochleo-dentate degeneration associated with severe peripheral neuropathy and caused by peroxisomal D-bifunctional protein deficiency.

The clinical, neuroradiological, neuropathological and biochemical findings in a patient with optico-cochleo-dentate degeneration (OCDD; OMIM 258700) are presented in a severe case succumbing at the age of 4 years. The electron microscopic and biochemical data showed for the first time that OCDD may occur as the phenotypic expression of D-bifunctional protein deficiency, i.e., a peroxisomal disorder. The boy was born as the first child of healthy, consanguineous parents of Turkish origin. No other family members were affected. The main clinical symptoms consisted of muscle hypotonia ("floppy infant"), generalized epileptic fits, hypacusis, rotatory nystagmus, insufficient pupillary reactions, and mental retardation. Fibroblast cultures revealed D-bifunctional protein deficiency. Neuropathological examination displayed moderate frontoparietal and insular microgyria, and atrophy of the cerebellum. Loss of neurons was severe in the granular layer, the Purkinje cell band of the cerebellum, and rather complete in the dentate nucleus. A corresponding loss of myelinated fibers associated with characteristic periodic acid-Schiff-positive macrophages was most prominent in the white matter of the cerebellum. There was additional severe loss of myelinated fibers in the central portions of the optic nerve, reduction of the nerve fiber density in the cochlear nerve, and reduction of myelinated nerve fibers by about 80-90% in the sural nerve, which has not been studied in previous cases. At the electron microscopic level, characteristic inclusions mainly in perivascular macrophages and astrocytes were the most prominent finding. The inclusions usually showed a bilaminar structure, whereas trilaminar structures, typically seen in adrenoleukodystrophy, and multilaminar structures were less frequently seen.

Leopard spot retinal pigmentation in infancy indicating a peroxisomal disorder.

BACKGROUND: Neonatal adrenoleucodystrophy (NALD) is a rare disorder resulting from abnormal peroxisomal biogenesis. Affected patients present in infancy with developmental delay, hypotonia, and seizures. Blindness and nystagmus are prominent features. The authors suggest a characteristic leopard spot pigmentary pattern in the peripheral retina to be diagnostic. METHODS: Three patients are reported with this presentation; the characteristic retinal appearance resulted in early diagnosis for one of these. CONCLUSION: Leopard spot retinopathy in an infant with hypotonia, seizures, developmental delay, with or without dysmorphic features and hearing impairment, is a clue to the diagnosis of NALD.

Cataract in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD).

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare metabolic disorder that can lead to acute encephalopathy, liver disease, cardiomyopathy, rhabdomyolysis, and long-term complications involving the eye and peripheral nerves. LCHADD is a peroxisome biogenesis disorder (PBD). Except for the series presented by Tyni and colleagues (Ophthalmology 1998;105:810-824), which described visually insignificant lens opacities in association with LCHADD, previous ophthalmic papers have only reported retinal complications. We report on one case with progressive asymmetrical cataract. The more mildly affected eye had a similar morphology to that previously reported and the more severely affected eye had an unusual morphology we believe is unique to LCHADD. We discuss the range of ophthalmic presentations in our cases and in the literature. The variability of the severity of ocular complications, even between eyes in one individual, makes it difficult to test the effectiveness of therapeutic options upon the ophthalmic complications.