Familial occurrence of intestinal obstruction in children with the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS)

Familial Pernicious Chronic Intestinal Pseudo-obstruction with a Mitochondrial DNA A3243G Mutation

We report the case of a mother and two children who shared a mitochondrial DNA A3243G mutation. The mother had diabetes mellitus, neurogenic bladder, bradykinesia, dystonia, and slowly progressive cerebellar ataxia. Her two daughters were diagnosed with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes at adolescence. They all presented with gastrointestinal symptoms at an advanced clinical stage. They were diagnosed with chronic intestinal pseudo-obstruction, and they were resistant to therapy. The mother and her youngest daughter died from aspiration pneumonia because of vomiting. The determination of chronic intestinal pseudo-obstruction is an important prognostic factor in patients with the mitochondrial DNA A3243G variant.

Pseudo-obstruction, stroke, and mitochondrial dysfunction: A lethal combination

OBJECTIVES

The m.3243A>G MTTL1 mutation is the most common cause of mitochondrial disease; yet there is limited awareness of intestinal pseudo-obstruction (IPO) in this disorder. We aimed to determine the prevalence, severity, and clinical outcome of patients with m.3243A>G-related mitochondrial disease manifesting with IPO.

METHODS

In this large, observational cohort study, we assessed the clinical, molecular, and radiological characteristics of patients with genetically determined m.3243A>G-related mitochondrial disease, who presented with severe symptoms suggestive of bowel obstruction in the absence of an occluding lesion.

RESULTS

Between January 2009 and June 2015, 226 patients harbouring the m.3243A>G mutation were recruited to the Medical Research Council Centre Mitochondrial Disease Patient Cohort, Newcastle. Thirty patients (13%) presented acutely with IPO. Thirteen of these patients had a preceding history of stroke-like episodes, whereas 1 presented 27 years previously with their first stroke-like episode. Eight patients developed IPO concomitantly during an acute stroke-like episode. Regression analysis suggested stroke was the strongest predictor for development of IPO, in addition to cardiomyopathy, low body mass index and high urinary mutation load. Poor clinical outcome was observed in 6 patients who underwent surgical procedures.

INTERPRETATION

Our findings suggest, in this common mitochondrial disease, that IPO is an under-recognized, often misdiagnosed clinical entity. Poor clinical outcome associated with stroke and acute surgical intervention highlights the importance of the neurologist having a high index of suspicion, particularly in the acute setting, to instigate timely coordination of appropriate care and management with other specialists. Ann Neurol 2016;80:686-692.

Mitochondrial tRNA valine as a recurrent target for mutations involved in mitochondrial cardiomyopathies

The aim of this study was to identify the genetic defect in two patients having cardiac dysfunction accompanied by neurological symptoms, and in one case MRI evidence of cortical and cerebellar atrophy with hyperintensities in the basal ganglia. Muscle biopsies from each patient revealed single and combined mitochondrial respiratory chain deficiency. The complete mtDNA sequencing of both patients revealed two transitions in the mitochondrial tRNA(Val) gene (MT-TV) (m.1628C>T in Patient 1, and m.1644G>A in Patient 2). The functional and molecular analyses reported here suggest that the MT-TV gene should be routinely considered in the diagnosis of mitochondrial cardiomyopathies.

Unusual occurrence of intestinal pseudo obstruction in a patient with maternally inherited diabetes and deafness (MIDD) and favorable outcome with coenzyme Q10

Maternally inherited diabetes and deafness (MIDD) has been related to an A to G transition in the mitochondrial tRNA Leu (UUR) gene at the base pair 3243. This subtype of diabetes is characterized by maternal transmission, young age at onset and bilateral hearing impairment. Besides diabetes and deafness, the main diagnostic features, a wide range of multisystemic symptoms may be associated with the A3243G mutation. Organs that are most metabolically active, such as muscles, myocardium, retina, cochlea, kidney and brain are frequently affected. Gastrointestinal tract symptoms are also common in patients with mitochondrial disease and constipation and diarrhea are the most frequent manifestations. However, there are few prior reports of intestinal pseudo obstruction in MIDD patients. Here we report the case of a patient with MIDD associated with the mtDNA A3243G mutation who developed chronic intestinal pseudo obstruction, and the introduction of Coenzyme Q10 as adjunctive therapy led to a solution of the pseudo obstruction.

Frequency of mitochondrial defects in patients with chronic intestinal pseudo-obstruction

BACKGROUND & AIMS

Chronic intestinal pseudo-obstruction (CIPO) is a rare disorder caused by intestinal dysmotility and characterized by chronic symptoms suggesting bowel obstruction in the absence of fixed, occluding lesions. CIPO has been associated with primary defects of the mitochondrial oxidative phosphorylation pathway, although the frequency of mitochondrial disorders in patients with CIPO is unknown. This study evaluates mitochondrial function in patients with CIPO.

METHODS

A retrospective study was performed of data collected from 80 CIPO patients at a tertiary centre over a 25-year period. Mitochondrial disorders were detected by analysis of serum lactate and thymidine phosphorylase activities, brain magnetic resonance images, and muscle biopsies. Genes encoding thymidine phosphorylase, mitochondrial DNA tRNA(leu(UUR)) or tRNA(lys), and DNA polymerase-gamma were analyzed for mutations.

RESULTS

Mitochondrial defects were identified in 15 patients (10 women; median age at diagnosis 32 years), representing 19% of the study cohort. All 15 patients had extra-digestive symptoms, 5 had mutations in the thymidine phosphorylase gene, 2 had mutations in tRNA(leu(UUR)), and 5 had mutations in the DNA polymerase-gamma gene. No genetic defect was detected in 3 of the patients with mitochondrial disorders. Patients with mitochondrial CIPO differed from patients without mitochondrial defects in their very severe nutritional status (frequent and long-term requirement for parenteral nutrition) and poor prognosis (frequent digestive and neurologic complications that led to a high incidence of premature death).

CONCLUSION

Mitochondrial disorders seem to be an important cause of CIPO. Patients with CIPO, especially severe cases with associated neurologic symptoms, should be tested for mitochondrial defects.

Heteroplasmic mutation in the anticodon-stem of mitochondrial tRNA(Val) causing MNGIE-like gastrointestinal dysmotility and cachexia

While mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is typically associated with mutations in the nuclear gene encoding for thymidine phosphorylase (ECGF1, TYMP), a similar clinical phenotype was described in patients carrying mutations in the nuclear-encoded polymerase gamma (POLG1) as well as a few mitochondrial tRNA genes. Here we report a novel mutation in the mitochondrial tRNA(Val) (MTTV) gene in a girl presenting with clinical symptoms of MNGIE-like gastrointestinal dysmotility and cachexia. Clinical, histological, biochemical and single cell investigations were performed. The heteroplasmic m.1630A>G mutation was detected in the mitochondrial tRNA(Val) (MTTV) gene in the patient's muscle, blood leukocytes and myoblasts, as well as in blood DNA of the unaffected mother. We provide clinical, biochemical, histological, and molecular genetic evidence on the single cell level for the pathogenicity of this mutation. Our finding adds to the genetic heterogeneity of MNGIE-like gastrointestinal symptoms and highlights the importance of a thorough genetic workup in case of suspected mitochondrial disease.

Mitochondrial DNA A3243G mutation involved in familial diabetes, chronic intestinal pseudo-obstruction and recurrent pancreatitis

AIMS

To report on a family with five members who carry the A3243G mutation in mitochondrial tRNA for leucine 1 (MTTL1) and present with diabetes, chronic intestinal pseudo-obstruction (CIPO) and recurrent pancreatitis, and to screen for this mutation in a cohort of 36 unrelated patients with recurrent pancreatitis.

METHODS

The mutation was quantified in several tissue samples from patients. Respiratory chain activity was studied in muscle biopsies and fibroblast cultures. In addition, the thymidine phosphorylase gene (TP) involved in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and three genes involved in chronic pancreatitis - PRSS1, SPINK1 and CFTR - were sequenced in affected patients. Finally, the MTTL1 gene was examined in 36 unrelated patients who had recurrent pancreatitis, but no mutations in the PRSS1 and SPINK1 genes.

RESULTS

Heteroplasmy for the mtDNA A3243G mutation was found in all tissue samples from these patients, but no mutations were found in the genes coding for thymidine phosphorylase, PRSS1, SPINK1 and CFTR. Also, none of the 36 unrelated patients with recurrent pancreatitis were carrying any MTTL1 mutations.

CONCLUSION

The mtDNA A3243G mutation associated with the gastrointestinal manifestations observed in the affected family should be regarded as a possible cause of CIPO and unexplained recurrent pancreatitis. However, the mutation is probably only weakly involved in cases of isolated recurrent pancreatitis.

Intestinal pseudo-obstruction in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) associated with phenytoin therapy

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is most commonly associated with a mitochondrial DNA A to G point mutation at nucleotide 3243 (A3243G) and individuals with the disorder present a wide range of multisystemic symptoms. Seizures in MELAS patients are often intractable and require multiple antiepileptic drugs. Here we report a MELAS patient who presented with acute intestinal pseudo-obstruction following the administration of phenytoin (PHT) as an antiepileptic treatment. She presented with the first stroke-like episode at the age of 6 years and mitochondrial DNA analysis revealed A3243G with 94% mutation load in skeletal muscle. Despite treatment with phenobarbital and clobazam at the age of 16 years, she developed status epilepticus which ceased following PHT infusion. Thereafter, she was started on PHT treatment. One month later, however, she was readmitted because of remarkable abdominal distention. Although abdominal CT showed acute ileus with hepatic portal venous gas mimicking surgical emergency, the abdominal distention gradually recovered over several days following the discontinuation of PHT. Our clinical observations suggest the possibility that intestinal pseudo-obstruction in this patient related to PHT therapy. Careful clinical observation including gastrointestinal symptoms is required in the management of epilepsy in MELAS patients.

Gastric emptying in patients with Type 2 diabetes mellitus and diabetes associated with mitochondrial DNA 3243 mutation using 13C-octanoic acid breath test

Although the (13)C-octanoic acid breath test (OBT) has been applied to diabetic patients for assessing gastric emptying, such studies are still limited. Gastric emptying was measured using solid meal containing (13)C-octanoic acid in 52 patients with Type 2 diabetes mellitus and 4 diabetic patients with mitochondrial DNA (mitDNA) 3243 mutation. Delayed gastric emptying was detected in 29% of patients with Type 2 diabetes mellitus, and multiple regression analysis showed that gastric emptying was independently associated with gastrointestinal symptoms and cardiac autonomic neuropathy. Gastric emptying was not related to gastric dysrhythmia in cutaneous electrogastrography (EGG). Diabetic patients with mitDNA 3243 mutation showed delayed gastric emptying. Because the pathogenesis of delayed gastric emptying is multifactorial in diabetic patients, the recently developed OBT is useful for studying gastric emptying in various clinical settings of diabetic patients.

Paralytic ileus in MELAS with phenotypic features of MNGIE

This report describes a child having the syndrome of overlapping phenotypic features of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE). Mitochondrial DNA analysis revealed a point mutation at position A3243G, whereas activity of thymidine phosphorylase and its corresponding gene analysis were normal. The most striking feature of this case was paralysis of one segment of the terminal ileum observed on laparotomy. The electron microscopic findings of the resected ileum and colon by limited right hemicolectomy disclosed accumulation of numerous enlarged mitochondria with ill-defined cristae which were similar to mitochondria reported in three previous MELAS cases and one MNGIE case with intestinal dysmotility. We emphasize that the MELAS and MNGIE phenotypes overlapped in this case and that the mechanism of acute ileus in MELAS was associated with functional paralysis of the intestine.

Gastrointestinal tract symptoms in Maternally Inherited Diabetes and Deafness (MIDD)

OBJECTIVE

To evaluate the prevalence and clinical consequences of gastro-intestinal manifestations in Maternally Inherited Diabetes and Deafness syndrome (MIDD).

METHODS

We report the case of fatal intestinal pseudo-obstruction in a patient with severe MIDD. Using a standardized questionnaire, we evaluate the frequency of gastrointestinal tract (GIT) symptoms in 10 patients with MIDD (8 A3243G and 2 T14709C mutations of mitochondrial DNA). The reference population consisted of 50 patients with type 1 diabetes matched for disease duration. In 4 patients with digestive manifestations endoscopic examination of upper and lower GIT was performed allowing multiple biopsies for ultrastructural and molecular analysis.

RESULTS

GIT symptoms were frequently reported in MIDD specially in patients bearing the mt 3243 mutation. The manifestations i.e. constipation, diarrhea or both, were more frequent in this subgroup than in type 1 diabetic population (88% vs 28%, p<0.05). Ileus is a rare and severe complication with a frequent fatal Issue. Ultrastructural analysis of the mucosa from oesophagus, stomach, duodenum, colon and rectum showed mild modifications such as accumulation of normal mitochondria and lipId droplets. Heteroplasmy levels were determined in 4 patients harboring the 3243 mutation. In three patients the percentage of mutated DNA increased from upper to lower GIT.

CONCLUSIONS

Gastrointestinal symptoms are frequent in MIDD secondary to 3243 mutation. They might explain the lower body weight observed in these patients in comparison to reference diabetic populations. They can also lead to a severe complication namely the intestinal pseudo-obstruction.

Abnormalities in gastrointestinal motility are associated with diseases of oxidative phosphorylation in children

OBJECTIVE

Disorders of the mitochondrial electron transport chain enzymes of oxidative phosphorylation (OXPHOS) have neurologic, musculoskeletal, ophthalmologic, cardiac, and GI manifestations. Many adult and pediatric patients with disorders of OXPHOS have abnormalities in intestinal motility. The purpose of this study was to describe pediatric patients who initially presented with signs of GI dysmotility and were later evaluated and found to have a disorder of OXPHOS.

METHODS

Data were collected on six patients, including initial GI and neurologic symptoms, histology of skeletal muscle biopsies, mitochondrial DNA mutational analysis, OXPHOS enzyme assay, upper GI barium imaging, technetium-99M liquid gastric emptying scan, upper GI endoscopy, esophageal manometry, and antroduodenal manometry.

RESULTS

All six children presented with symptoms of GI dysmotility within 2 wk of life. Patients later developed symptoms of neurologic disorders. All patients had abnormalities in OXPHOS enzyme analysis. Muscle histology showed nonspecific changes with no ragged red fibers. Sequencing of the mitochondrial DNA showed no recognized mutations. No patient had any evidence of intestinal obstruction or malrotation by upper GI barium imaging. Four patients had delayed gastric emptying. Three patients had endoscopic and histologic evidence of esophagitis. All six had demonstrable neuropathic abnormalities by antroduodenal manometry, including the following: nonpropagated antral bursts, absent migrating motor complexes, postprandial antral hypomotility, retrograde migrating motor complexes, and tonic contractions with the migrating motor complex.

CONCLUSIONS

Abnormalities in GI motility may be an early presenting sign of disorders of OXPHOS in children.

Intestinal pseudo-obstruction and urinary retention: cardinal features of a mitochondrial DNA-related disease

The syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystemic disorder associated in most of the patients with an A to G transition at nucleotide position 3243 in the transfer RNA (tRNA)Leu(UUR) (A3243G) of the mitochondrial DNA. This syndrome is characterized by the preponderant involvement of skeletal muscle and central nervous system, but urinary or gastrointestinal symptoms are seldom documented. Here we report an unusual case of a 52-year-old woman with a clinical phenotype characterized by encephalopathy, left hemiparesis, urinary retention and gastrointestinal pseudo-obstruction. She had the classical A3243G mitochondrial DNA point mutation of MELAS syndrome. We also present a clinically heterogeneous multigenerational pedigree with several affected members in the maternal lineage.