Familial mitochondrial intestinal pseudo-obstruction and neurogenic bladder

Urologic presentations and management options in pediatric mitochondrial disease

OBJECTIVE

To review the evaluation and management of urologic pathology related to mitochondiral diseases (MD) in childhood.

METHODS

A retrospective review was performed of patients with MD from 1/1/2000 - 10/8/2020 who were referred for urologic evaluation at a single childrens hospital. Clinical and demographic information was reviewed including symptomatology, urodynamic evaluation, and medical/surgical management.

RESULTS

15 patients were identified for inclusion. Median age of presentation was 5 years and median follow up was 4 years. Patients presented with numerous urologic complaints including urinary retention/incomplete emptying, incontinence, and recurrent urinary tract infection. Urodynamics demonstrated elevated median bladder capacity at 172% of expected as calculated by age. Detrusor sphincter dyssynergia (DSD) was present in 6 (50%). Progression to surgical intervention occurred in 67% at a median time of 3.5 years after initial referral. This included suprapubic tube (SPT) placement and sacral neuromodulation (SNM).

CONCLUSIONS

Patients in this study were found to have a spectrum of lower urinary tract dysfunction (LUTD) with elevated bladder capacity being common. No singular urodynamic feature prevailed although DSD was found in 50%. Progression of symptoms over time was also common. Most patients (67%) did go on to surgical intervention including SPT and SNM. Clinicians should be aware of the possibility of LUTD in children with MD and they should be promptly referred to pediatric urology when LUTD is suspected.

Intestinal pseudoobstruction

Intestinal pseudoobstruction is an uncommon clinical condition of varied etiologies. Confusion in its characterization and diagnosis often results in delay in diagnosis as well as inappropriate treatment involving repeated surgery. The various aspects and characteristics of intestinal pseudoobstruction are described by representative case reports of three patients treated in our department with a review of the literature. Heightened awareness, understanding of the physiological dynamics and recognition of the spectrum of its clinical presentation and diagnostic modalities should result in more efficacious treatment.

Yeast models of human mitochondrial diseases: from molecular mechanisms to drug screening

Mitochondrial diseases are rare diseases most often linked to energy in the form of ATP-depletion. The high number of nuclear- and mitochondrial-DNA-encoded proteins (>500), required for ATP production and other crucial mitochondrial functions such as NADH re-oxidation, explains the increasing number of reported disorders. In recent years, yeast has revealed to be a powerful model to identify responsible genes, to study primary effects of pathogenic mutations and to determine the molecular mechanisms leading to mitochondrial disorders. However, the clinical management of patients with mitochondrial disorders is still essentially supportive. Here we review some of the most fruitful yeast mitochondrial disorder models and propose to subject these models to highthroughput chemical library screening to prospect new therapeutic drugs against mitochondrial diseases.

From the bench to the 'crib'-side: implications of scientific advances to paediatric neurogastroenterology and motility

Paediatric gastrointestinal motility disorders may present in the neonatal period as the result of a congenital insult that occurred during embryonic development or as a manifestation of an abnormal genetic background. Functional gastrointestinal and motility disorders may also be acquired and present during childhood as the first presentation of a condition that can persist or re-occur throughout adolescence and adulthood. These disorders can have a significant psychological and financial impact on the lives of the affected children and their families. Recently, enteric neuroscience research has advanced the understanding of the pathogenesis and treatment of uncommon congenital or developmental gastrointestinal motility disorders such as Hirschsprung disease and chronic intestinal pseudo-obstruction. In addition, research has contributed to improvements in the understanding of more prevalent functional gastrointestinal disorders in children, such as chronic constipation and functional abdominal pain syndromes. The purpose of this review is to highlight these advances with particular regard to the clinical impact they have in the understanding and management of disorders in the field of paediatric neurogastroenterology and motility.

Maternal inheritance in cyclic vomiting syndrome with neuromuscular disease

Cyclic vomiting syndrome (CVS), characterized by severe discrete episodes of nausea, vomiting, and lethargy, is a predominately childhood condition associated with migraine and dysautonomic features. Disease-associated mitochondrial DNA (mtDNA) sequence variants are suggested by a strong maternal bias in the inheritance of migraine, and the recent findings of mtDNA variants in a few children with CVS and additional neuromuscular disease manifestations ("CVS+"). A clinical interview using a questionnaire was administered (generally) to one parent of 62 children with CVS+. Non-senile disease manifestations, including migraine, myopathy, seizures, and dysautonomia-like symptoms, were far more common in matrilineal versus non-matrilineal relatives, including being present in 75% of the mothers versus in only 11% of the fathers (P < 0.001). Overall, maternal inheritance is suggested in 86% of the families (in 65% strongly so). Disease manifestations in subjects and their affected matrilineal relatives are predominately intermittent and consistent with dysautonomia, including increased vital sign fluctuations. Body fluid metabolites and muscle biopsy findings are consistent with mitochondrial dysfunction in most cases tested. We conclude that mtDNA sequence variants are at least risk factors in the development of disease in most children at this "severe" end of the CVS spectrum, likely involving a maternally inherited propensity towards dysautonomia.

Diagnosis and management of mitochondrial diseases

Mitochondrial dysfunction should be considered in the differential diagnosis of any progressive multisystem disorder. The diagnosis is most challenging when only one symptom is present. In contrast, the diagnosis is easier to consider when two or more seemingly unrelated symptoms are present, involving more than one organ system. It is important to consider the diagnosis of a mitochondrial disorder when dealing with an unexplained association of symptoms, with an early onset and progressive course involving seemingly unrelated organs. The investigation can be relatively straightforward if a person has a recognizable phenotype and if it is possible to identify a known pathogenic mtDNA mutation. The difficulty arises when no known mtDNA defect can be found or when the clinical abnormalities are complex and not easily matched to those of more common mitochondrial disorders. In summary: A full mitochondrial evaluation often is warranted in children with a complex neurologic picture or a single neurologic symptom and other system involvement. When the presentation is classic for a maternally inherited mitochondrial syndrome, such as MELAS, MERRF, or Leber's hereditary optic neuropathy, appropriate mtDNA studies should be obtained first. When the clinical picture is classic for a nuclear DNA inherited syndrome and the gene or linkage is known, such as MNGIE, the clinician should proceed with genetic studies. When the clinical picture is nonspecific but highly suggestive of a mitochondrial disorder, the clinician should start with plasma or CSF lactic acid, ketone bodies, plasma acylcarnitines, and urinary organic acids. If these studies are abnormal, the clinician should proceed with muscle biopsy and assessment of the respiratory chain enzymes. Normal plasma or CSF lactic acid does not rule out a mitochondrial disorder.