Diagnosis, genetic characterization and clinical follow up of mitochondrial fatty acid oxidation disorders in the new era of expanded newborn screening: A single centre experience.

INTRODUCTION: Mitochondrial fatty acid oxidation disorders (FAODs) are a heterogeneous group of hereditary autosomal recessive diseases included in newborn screening (NBS) program in Italy. The aim of this study was to analyse FAODs cases, identified either clinically or by NBS,for clinical and genetic characterization and to evaluate a five years' experience of NBS, in the attempt to figure out the complexity of genotype-phenotype correlation and to confirm the clinical impact of NBS in our centre experience. MATERIALS AND METHODS: We analysed FAODs patients diagnosed either by NBS or clinically, followed since February 2014 to April 2019 at the Regional Screening Centre and Inherited Metabolic Diseases Unit of Verona. Diagnosis was confirmed by plasma acylcarnitines, urinary organic acids, enzymatic and genetic testing. For not clear genotypes due to the presence of variants of uncertain significance, in silico predictive tools have been used as well as enzymatic activity assays. Patients underwent clinical, nutritional and biochemical follow up. RESULTS: We diagnosed 30 patients with FAODs. 20 by NBS: 3 CUD, 6 SCADD, 5 MCADD, 4 VLCADD, 2 MADD. Overall incidence of FAODs diagnosed by NBS was 1:4316 newborns. No one reported complications during the follow up period. 10 patients were diagnosed clinically: 2 CUD, 2 CPT2D, 1 VLCADD, 5 MADD. Mean age at diagnosis was 29.3 years. Within this group, complications or symptoms were reported at diagnosis, but not during follow-up. 12 mutations not previously reported in literature were found, all predicted as pathogenic or likely pathogenic. DISCUSSION AND CONCLUSIONS: Our study highlighted the great phenotypic variability and molecular heterogeneity of FAODs and confirmed the importance of a tailored follow up and treatment. Despite the short duration of follow up, early identification by NBS prevented diseases related complications and resulted in normal growth and psycho-motor development as well.

Neurofibromatosis type 1 in two siblings due to maternal germline mosaicism.

Neurofibromatosis type 1 (NF1) is caused by loss of function mutations of the NF1 gene, which are de novo in 50% of cases. Although this gene shows one of the highest mutation rates in the human genome, germline mosaicism is very rare in this condition. We describe the molecular analysis of a family in which neurofibromatosis type 1 occurred in two out of four siblings born to unaffected parents. Molecular analysis of the NF1 gene identified in both patients the same splicing mutation c.1392+1G>A, which was absent in parental lymphocytes. Microsatellite analysis showed that the two affected siblings shared the same maternal allele, however a specific PCR-RFLP assay excluded the presence of the NF1 splicing mutation in multiple maternal tissues. Our molecular and clinical findings are consistent with a germline mosaicism for the NF1 splicing mutation. This is the first case of maternal germline mosaicism for a NF1 mutation characterized so far at the molecular level. Our data confirm that germline mosaicism is rare in neurofibromatosis 1, but it has important implications for genetic counseling.

Prevalence of AIP mutations in a large series of sporadic Italian acromegalic patients and evaluation of CDKN1B status in acromegalic patients with multiple endocrine neoplasia.

BACKGROUND: Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene and the p27(KIP1) encoding gene CDKN1B have been associated with two well-defined hereditary conditions, familial isolated pituitary adenoma (FIPA) and multiple endocrine neoplasia type 4 (MEN4). Somatotropinomas are present in most AIP mutated FIPA kindreds, as well as in two-thirds of MEN4 patients who carry pituitary tumors. METHODS: Germline DNA samples of 131 Italian sporadic acromegalic patients including 38 individuals with multiple tumors, and of six FIPA families (four homogeneous for prolactinomas and two heterogeneous with prolactin/nonfunctioning pituitary adenomas) were collected in a multicentric collaborative study. The prevalence of AIP and CDKN1B gene point mutations and copy number variations were evaluated. RESULTS: Two novel (IVS3+1G>A and c.871G>A) and one previously described (c.911G>A) AIP mutations were detected in four apparently sporadic cases (3.1%) with relatively high age at diagnosis (49+/-18, range 30-67). No mutations/rearrangements were detected in FIPA families. The highly conserved c.871G>A substitution was detected in a patient who also carried a MEN1 mutation suggesting that she is a double heterozygote. The possible pathogenic effect on AIP splicing of the silent substitution c.144G>A found in another patient was ruled out using a minigene-based approach. CDKN1B mutations/rearrangements were neither identified in patients with multiple neoplasia nor in FIPA families. CONCLUSION: AIP is mutated in about 3% of apparently sporadic acromegalic patients. The relatively high age at diagnosis, as well as its sporadic presentation, suggests that these patients are carriers of mutations with reduced pathogenicity. p27(KIP1) is unlikely to represent the common unifying nonendocrine etiology for acromegaly and cancer.

Coenzyme Q10 distribution in blood is altered in patients with fibromyalgia.

OBJECTIVE: Coenzyme Q10 (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Signs and symptoms associated with muscular alteration and mitochondrial dysfunction, including oxidative stress, have been observed in patients with fibromyalgia (FM). The aim was to study CoQ(10) levels in plasma and mononuclear cells, and oxidative stress in FM patients. METHODS: We studied CoQ(10) level by HPLC in plasma and peripheral mononuclear cells obtained from patients with FM and healthy control subjects. Oxidative stress markers were analyzed in both plasma and mononuclear cells from FM patients. RESULTS: Higher level of oxidative stress markers in plasma was observed respect to control subjects. CoQ(10) level in plasma samples from FM patients was doubled compared to healthy controls and in blood mononuclear cells isolated from 37 FM patients was found to be about 40% lower. Higher levels of ROS production was observed in mononuclear cells from FM patients compared to control, and a significant decrease was induced by the presence of CoQ(10). CONCLUSION: The distribution of CoQ(10) in blood components was altered in FM patients. Also, our results confirm the oxidative stress background of this disease probably due to a defect on the distribution and metabolism of CoQ(10) in cells and tissues. The protection caused in mononuclear cells by CoQ(10) would indicate the benefit of its supplementation in FM patients.

Diagnostic challenges in facioscapulohumeral muscular dystrophy.

The diagnosis of facioscapulohumeral muscular dystrophy (FSHD) can be difficult due to its clinical variability and complex genetic cause. We present three challenging cases: one misdiagnosis of FSHD, one patient with FSHD resembling mitochondrial myopathy, and one patient with combined FSHD and limb girdle muscular dystrophy 2A. Detailed clinical and genetic evaluation, including 4qA/4qB allele determination, may be needed for the diagnosis of FSHD.

Infantile encephalomyopathy and nephropathy with CoQ10 deficiency: a CoQ10-responsive condition.

Coenzyme Q10 (CoQ10) deficiency has been associated with various clinical phenotypes, including an infantile multisystem disorder. The authors report a 33-month-old boy who presented with corticosteroid-resistant nephrotic syndrome in whom progressive encephalomyopathy later developed. CoQ10 was decreased both in muscle and in fibroblasts. Oral CoQ10 improved the neurologic picture but not the renal dysfunction.

Mitochondrial DNA depletion: mutations in thymidine kinase gene with myopathy and SMA.

BACKGROUND: The mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an autosomal recessive disorder of early childhood characterized by decreased mtDNA copy number in affected tissues. Recently, MDS has been linked to mutations in two genes involved in deoxyribonucleotide (dNTP) metabolism: thymidine kinase 2 (TK2) and deoxy-guanosine kinase (dGK). Mutations in TK2 have been associated with the myopathic form of MDS, and mutations in dGK with the hepatoencephalopathic form. OBJECTIVES: To further characterize the frequency and clinical spectrum of these mutations, the authors screened 20 patients with myopathic MDS. RESULTS: No patient had dGK gene mutations, but four patients from two families had TK2 mutations. Two siblings were compound heterozygous for a previously reported H90N mutation and a novel T77M mutation. The other siblings harbored a homozygous I22M mutation, and one of them had evidence of lower motor neuron disease. The pathogenicity of these mutations was confirmed by reduced TK2 activity in muscle (28% to 37% of controls). CONCLUSIONS: These results show that the clinical expression of TK2 mutations is not limited to myopathy and that the myopathic form of MDS is genetically heterogeneous.

Acute disseminated encephalomyelitis associated with hepatitis C virus infection.

BACKGROUND: Acute disseminated encephalomyelitis (ADEM) is an autoimmune demyelinating disease of the central nervous system that is frequently preceded by an acute viral infection. This is the first reported case of ADEM associated with hepatitis C virus (HCV) infection. CASE DESCRIPTION: A 46-year-old woman underwent a surgical procedure and received multiple blood transfusions, at which time serologic testing for HCV was negative. Fifty days later, she suddenly developed seizures, alteration of consciousness, right hemiparesis, hemianopsia, and urinary retention. Magnetic resonance imaging revealed symmetric multifocal changes on T2-weighted images in the cerebral gray and white matter and in the cerebellar white matter with some lesion enhancement after gadolinium administration. Blood testing showed a recent HCV infection with high titer of IgM early antigens and a strongly positive reaction for HCV RNA. All other microbiological and virological test results were negative both in serum and in cerebrospinal fluid. Treatment with high-dose dexamethasone was followed by a dramatic improvement of the clinical and magnetic resonance picture. Within a few months the patient recovered completely and there were no relapses during 2 years of follow-up. CONCLUSIONS: Infection with HCV is associated with several autoimmune neurological manifestations. It is recommended the patients with ADEM be screened for HCV.

Acute quadriplegic myopathy in a 17-month-old boy.

Acute quadriplegic myopathy is a rare condition associated with the use of nondepolarizing muscle-blocking agents and corticosteroids in the course of severe systemic illness. A 17-month-old boy underwent liver transplantation for fulminant hepatitis. He was intubated for 24 days and treated with vecuronium bromide and high-dose methylprednisolone. The child was weaned from the ventilator and presented extreme weakness in the upper limbs and total paralysis of the lower limbs. Serum creatine kinase level was normal and electromyography showed myopathic abnormalities. Muscle biopsy showed severe type-1 fiber atrophy and selective loss of myosin thick filaments was seen on electron microscopy. Scattered regenerating fetal myosin-positive fibers were present, mu calpain was absent, while m calpain was diffusely expressed. Physical therapy was immediately started and the child recovered even though corticosteroids were not discontinued. The pathogenesis of acute quadriplegic myopathy is still unknown. We suggest that it could be due to abnormal protein turnover in the muscle. Several independent factors, such as corticosteroid treatment, immobilization, or cytokines, could take part in a cascade of events that leads to an excessive yet selective degradation of proteins involving myosin thick filaments and possibly components of sarcolemma, causing muscle inexcitability.

Diencephalic syndrome and disseminated juvenile pilocytic astrocytomas of the hypothalamic-optic chiasm region.

BACKGROUND: Diencephalic syndrome (DS) is a complex of signs and symptoms related to hypothalamic dysfunction; its main features are emaciation, despite a normal or slightly diminished caloric intake, and an alert appearance. DS has been almost exclusively described in association with space-occupying lesions of the hypothalamic-optic chiasm region, mainly juvenile pilocytic astrocytoma (JPA). A systematic diagnostic approach, including contrast-enhanced magnetic resonance imaging (MRI) of the child's head, is rapidly expanding our knowledge of this syndrome. METHODS: The MRI findings for three children affected by DS associated with biopsy-proven JPA, consecutively referred to the Pediatric Neuro-Oncology Program of the Department of Pediatrics at the University of Padua between September 1991 and January 1996, are presented in this article. The children were boys, ages 6, 7, and 18 months, respectively. RESULTS: In all three patients, the initial contrast-enhancing MRIs of the head showed evidence of tumor dissemination. This finding prompted a study of the spine, which in turn showed tumor deposits in all three subjects. Among the 43 patients younger than 16 years with low grade astroctyoma who consecutively entered the Neuro-Oncology Program during the study period, these 3 patients were the only ones who had disseminated tumors. CONCLUSIONS: In this study, the hypothesis was formulated that DS and disseminated hypothalamic-optic chiasm JPA tend to be more commonly associated than previously stated. This study suggests that the initial contrast-enhanced MRI of the head of a child affected by DS and hypothalamic JPA must be looked at carefully for evidence of tumor dissemination, and that the spine must also be examined if the findings are positive.