The genetics of incontinence: A scoping review.

The genetic causes underlying incontinence in both children and adults have begun to be unravelled during the last decades. The aim of this scoping review is to synthesize current knowledge on the genetics of childhood and adult urinary and faecal incontinence, identify similarities between different incontinence subgroups, and identify knowledge gaps to aid future research. PRISMA-ScR was used, and 76 studies were included. Early epidemiological family and twin studies suggest high heritability of incontinence. Linkage studies provide evidence for the existence of rare genetic variants; however, these variants have not been identified. Later candidate gene association studies and recent genome-wide association studies provide the first preliminary evidence that common risk variants also play a role. The genetics of incontinence in children and adults has predominantly been studied separately, but this review identifies for the first time the endothelin system as a potential common pathophysiological pathway. Overall, these findings strengthen the hypothesis that genetic variants play a prominent role in the pathogenesis of incontinence. Future research should include hypothesis-free studies of rare and common variants in large well-characterized cohorts with incontinence. Studies should include different age groups and ethnicities and both sexes to fully reveal the genetics of incontinence.

Characterization of symptom severity and impact on four fecal incontinence phenotypes in women presenting for evaluation.

AIM: To characterize symptom-specific distress and impact on quality of life (QOL) among women with urge, passive, and combined urge/passive fecal incontinence (FI) phenotypes. A secondary aim was to characterize FI symptom-specific distress and impact on women with a novel fourth phenotype, stress FI. METHODS: Women with at least monthly FI from 2003 to 2017 were included. Participants completed the Modified Manchester Health Questionnaire (MMHQ) including MHQ and Fecal Incontinence Severity Index (FISI). Anorectal manometry (ARM) and endoanal ultrasound (EAUS) testing was performed. Total MHQ and FISI scores were compared across FI subtypes controlling for pertinent baseline covariates. RESULTS: The cohort included 404 subjects, 220 meeting criteria for urge FI, 67 passive FI, and 117 combined urge/passive FI. On MHQ, women with combined urge/passive FI were most impacted (p < 0.01). FISI scores were significantly different from combined urge/passive FI having the greatest impact (38.1 ± 12.5) and urge FI (31.1 ± 11.3), p < 0.01 having the least. No differences were observed in ARM measurements or anal sphincter defects among the three groups (all p > 0.05). Twenty-nine subjects were identified with stress FI. There were no differences in overall MHQ or FISI scores or anal sphincter evaluation among the urge, passive, and stress FI groups (all p > 0.05). CONCLUSION: Women with combined urge/passive FI have higher symptom distress and impact on QOL than urge or passive FI alone. Further research is needed to determine the significance of stress FI as a subtype and response to treatment.

Genome-Wide Association Study for Urinary and Fecal Incontinence in Women.

PURPOSE: Urinary incontinence and fecal incontinence are common disorders in women that negatively impact quality of life. In addition to known health and lifestyle risk factors, genetics may have a role in continence. Identification of genetic variants associated with urinary incontinence and fecal incontinence could result in a better understanding of etiologic pathways, and new interventions and treatments. MATERIALS AND METHODS: We previously generated genome-wide single nucleotide polymorphism data from Nurses' Health Studies participants. The participants provided longitudinal urinary incontinence and fecal incontinence information via questionnaires. Cases of urinary incontinence (6,120) had at least weekly urinary incontinence reported on a majority of questionnaires (3 or 4 across 12 to 16 years) while controls (4,811) consistently had little to no urinary incontinence reported. We classified cases of urinary incontinence in women into stress (1,809), urgency (1,942) and mixed (2,036) subtypes. Cases of fecal incontinence (4,247) had at least monthly fecal incontinence reported on a majority of questionnaires while controls (11,634) consistently had no fecal incontinence reported. We performed a genome-wide association study for each incontinence outcome. RESULTS: We identified 8 single nucleotide polymorphisms significantly associated (p <5×10-8) with urinary incontinence located in 2 loci, chromosomes 8q23.3 and 1p32.2. There were no genome-wide significant findings for the urinary incontinence subtype analyses. However, the significant associations for overall urinary incontinence were stronger for the urgency and mixed subtypes than for stress. While no single nucleotide polymorphism reached genome-wide significance for fecal incontinence, 4 single nucleotide polymorphisms had p <10-6. CONCLUSIONS: Few studies have collected genetic data and detailed urinary incontinence and fecal incontinence information. This genome-wide association study provides initial evidence of genetic associations for urinary incontinence and merits further research to replicate our findings and identify additional risk variants.

Choline transporter-like 1 deficiency causes a new type of childhood-onset neurodegeneration.

Cerebral choline metabolism is crucial for normal brain function, and its homoeostasis depends on carrier-mediated transport. Here, we report on four individuals from three families with neurodegenerative disease and homozygous frameshift mutations (Asp517Metfs*19, Ser126Metfs*8, and Lys90Metfs*18) in the SLC44A1 gene encoding choline transporter-like protein 1. Clinical features included progressive ataxia, tremor, cognitive decline, dysphagia, optic atrophy, dysarthria, as well as urinary and bowel incontinence. Brain MRI demonstrated cerebellar atrophy and leukoencephalopathy. Moreover, low signal intensity in globus pallidus with hyperintensive streaking and low signal intensity in substantia nigra were seen in two individuals. The Asp517Metfs*19 and Ser126Metfs*8 fibroblasts were structurally and functionally indistinguishable. The most prominent ultrastructural changes of the mutant fibroblasts were reduced presence of free ribosomes, the appearance of elongated endoplasmic reticulum and strikingly increased number of mitochondria and small vesicles. When chronically treated with choline, those characteristics disappeared and mutant ultrastructure resembled healthy control cells. Functional analysis revealed diminished choline transport yet the membrane phosphatidylcholine content remained unchanged. As part of the mechanism to preserve choline and phosphatidylcholine, choline transporter deficiency was implicated in impaired membrane homeostasis of other phospholipids. Choline treatments could restore the membrane lipids, repair cellular organelles and protect mutant cells from acute iron overload. In conclusion, we describe a novel childhood-onset neurometabolic disease caused by choline transporter deficiency with autosomal recessive inheritance.

Incontinence in Phelan-McDermid Syndrome.

OBJECTIVE: The aim of the study was to evaluate gastrointestinal symptoms and continence in the context of Phelan-McDermid Syndrome (PMS). METHODS: A prospective evaluation of children with PMS (n = 17) at the National Institutes of Health. RESULTS: Parent-reported history of symptoms were common: constipation (65%), reflux (59%), choking/gagging (41%), and more than half received gastrointestinal specialty care. No aspiration was noted in 11/11 participants who completed modified barium swallows. Four participants met criteria for functional constipation, 2 of whom had abnormal colonic transit studies. Stool incontinence was highly prevalent (13/17) with nonretentive features present in 12/17. Participants who were continent had significantly smaller genetic deletions (P = 0.01) and higher nonverbal mental age (P = 0.03) compared with incontinent participants. CONCLUSIONS: Incontinence is common in PMS and associated with intellectual functioning and gene deletion size. Management strategies may differ based on the presence of nonretentive fecal incontinence, functional constipation, and degree of intellectual disability for children with PMS.

Anorectal Dysfunction in Presymptomatic Mutation Carriers and Patients with Huntington's Disease.

BACKGROUND: Huntington's disease (HD) patients often report anorectal dysfunction; however, in HD research no detailed analysis of these complaints has been published. OBJECTIVE: To report anorectal dysfunction in a systematically studied cohort of HD subjects. METHODS: In 54 HD patients (24 men) and 10 presymptomatic HD mutation carriers (2 men) and in 99 controls (44 men) a history of anal incontinence and constipation was obtained and data was compared accordingly. In HD mutation carriers a clinical neurologic assessment and in some cases anorectal manometry were performed. RESULTS: Defecation urgency was reported by 28% of our HD mutation carriers, soiling in 18% and fecal incontinence in 28%. Severe anal incontinence (solid stools) was found in 0% men / 10% women, moderate (liquid stools) in 21% / 13%, and mild (flatus only) in 67% / 47% of our HD subjects. Compared to controls, anal incontinence was significantly more common in HD subjects (p < 0.001). Severe chronic constipation was found in 4.2% men / 0.0% women, moderate in 8.3% / 0.0%, and mild in 21% / 27% of HD subjects. Constipation was more common in HD men (p = 0.02) than in HD women (p = 0.144). Anorectal dysfunction was not reported by 54% of our HD subjects. Patients reporting incontinence or constipation were significantly more depressed (r = 0.53, p = 0.001). Upon anorectal manometry reduced resting anal pressure was found in 4 of 6 HD women. CONCLUSIONS: Our study demonstrated significant bowel dysfunction in HD patients. We propose these symptoms to be of central autonomic origin, although we cannot exclude effects of medication. These often neglected symptoms in HD subjects require greater attention from physicians.

Effects of electroacupuncture combined with stem cell transplantation on anal sphincter injury-induced faecal incontinence in a rat model.

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) and acupuncture are known to mitigate tissue damage. This study aimed to investigate the therapeutic effects of combined electroacupuncture (EA) stimulation and BMSC injection in a rat model of anal sphincter injury-induced faecal incontinence (FI). METHODS: 60 Sprague-Dawley rats were randomly divided into five groups: sham-operated control, FI, FI+EA, FI+BMSC, and FI+BMSC+EA. The anorectal tissues were collected on days 1, 3, 7 and 14. Repair of the injured anal sphincter was compared using haematoxylin and eosin (HE) and immunocytochemiscal analyses with sarcomeric α actinin. The expression of stromal cell derived factor-1 (SDF-1) and monocyte chemoattractant protein-3 (MCP-3) was detected by quantitative reverse transcription PCR to evaluate the effects of EA on the homing of BMSCs. RESULTS: The therapeutic effect of combined EA+BMSCs on damaged tissue was the strongest among all the groups as indicated by HE and immunohistochemical staining. The expression of SDF-1 and MCP-3 was significantly increased by combined EA and BMSC treatment when compared with the other groups (P=0.01 to P<0.05), suggesting promotive effects of EA on the homing of BMSCs. CONCLUSION: The combination of EA and BMSC transplantation effectively repaired the impaired anal sphincters. The underlying mechanism might be associated with apparent promotive effects of EA on the homing of BMSCs. Our study provides a theoretical basis for the development of a non-surgical treatment method for FI secondary to muscle impairment.

The molecular basis of the genesis of basal tone in internal anal sphincter.

Smooth muscle sphincters exhibit basal tone and control passage of contents through organs such as the gastrointestinal tract; loss of this tone leads to disorders such as faecal incontinence. However, the molecular mechanisms underlying this tone remain unknown. Here, we show that deletion of myosin light-chain kinases (MLCK) in the smooth muscle cells from internal anal sphincter (IAS-SMCs) abolishes basal tone, impairing defecation. Pharmacological regulation of ryanodine receptors (RyRs), L-type voltage-dependent Ca(2+) channels (VDCCs) or TMEM16A Ca(2+)-activated Cl(-) channels significantly changes global cytosolic Ca(2+) concentration ([Ca(2+)]i) and the tone. TMEM16A deletion in IAS-SMCs abolishes the effects of modulators for TMEM16A or VDCCs on a RyR-mediated rise in global [Ca(2+)]i and impairs the tone and defecation. Hence, MLCK activation in IAS-SMCs caused by a global rise in [Ca(2+)]i via a RyR-TMEM16A-VDCC signalling module sets the basal tone. Targeting this module may lead to new treatments for diseases like faecal incontinence.

Graphic integration of causal factors of pelvic floor disorders: an integrated life span model.

There is growing interest in causal factors for pelvic floor disorders. These conditions include pelvic organ prolapse and urinary and fecal incontinence and are affected by a myriad of factors that increase occurrence of symptomatic disease. Unraveling the complex causal network of genetic factors, birth-induced injury, connective tissue aging, lifestyle and comorbid factors is challenging. We describe a graphical tool to integrate the factors affecting pelvic floor disorders. It plots pelvic floor function in 3 major life phases: (1) development of functional reserve during an individual's growth, (2) variations in the amount of injury and potential recovery that occur during and after vaginal birth, and (3) deterioration that occurs with advancing age. This graphical tool accounts for changes in different phases to be integrated to form a disease model to help assess the overlap of different causal factors.

Basic science and translational research in female pelvic floor disorders: proceedings of an NIH-sponsored meeting.

AIMS: To report the findings of a multidisciplinary group of scientists focusing on issues in basic science and translational research related to female pelvic floor disorders, and to produce recommendations for a research agenda for investigators studying female pelvic floor disorders. METHODS: A National Institutes of Health (NIH)-sponsored meeting was held on November 14-15, 2002, bringing together scientists in diverse fields including obstetrics, gynecology, urogynecology, urology, gastroenterology, biomechanical engineering, neuroscience, endocrinology, and molecular biology. Recent and ongoing studies were presented and discussed, key gaps in knowledge were identified, and recommendations were made for research that would have the highest impact in making advances in the field of female pelvic floor disorders. RESULTS: The meeting included presentations and discussion on the use of animal models to better understand physiology and pathophysiology; neuromuscular injury (such as at childbirth) as a possible pathogenetic factor and mechanisms for recovery of function after injury; the use of biomechanical concepts and imaging to better understand the relationship between structure and function; and molecular and biochemical mechanisms that may underlie the development of female pelvic floor disorders. CONCLUSIONS: While the findings of current research will help elucidate the pathophysiologic pathways leading to the development of female pelvic floor disorders, much more research is needed for full understanding that will result in better care for patients through specific rather than empiric therapy, and lead to the potential for prevention on primary and secondary levels.

Molecular and clinical correlations in autosomal dominant cerebellar ataxia with progressive macular dystrophy (SCA7).

Spinocerebellar ataxia 7 (SCA7) is caused by the expansion of an unstable CAG repeat in the first exon of the SCA7 gene. We have analyzed the SCA7 mutation in 19 families and one isolated case of various geographical origins, presenting with autosomal dominant cerebellar ataxia with progressive macular dystrophy. The SCA7 CAG repeat was expanded in 77 patients and in 11 at-risk individuals, with alleles containing from 37 to 130 repeats, demonstrating that SCA7 is genetically homogeneous. Repeats on normal alleles contained from 7 to 35 CAGs. There was a strong negative correlation (r = -0.84) between the age at onset and the size of the CAG repeat expansion in SCA7 patients. Larger expansions were associated with earlier onset, a more severe and rapid clinical course, and a higher frequency of decreased vision, ophthalmoplegia, extensor plantar response and scoliosis. The frequency of other clinical signs such as dysphagia and sphincter disturbances increased with disease duration. The mutation was highly unstable during transmission, with a mean increase of 10 +/- 16 CAG repeats, which was significantly greater in paternal (15 +/- 20) than in maternal (5 +/- 5) transmissions. This correlated well with the marked anticipation (19 +/- 13 years) observed in the families. Gonadal mosaicism, observed in the sperm of a patient, was particularly important, with expanded alleles ranging from 42 to >155 CAG repeats. The degree of instability during transmission, resulting mostly in expansions, is greater than in the seven other neurodegenerative disorders caused by polyglutamine expansions.

[Overflow incontinence--a rare manifestation of Peutz-Jeghers syndrome]. / Uberlaufinkontinenz--seltene Erscheinungsform des Peutz-Jeghers-Syndroms.

We present the case of a 12-year-old girl with Peutz-Jeghers syndrome (PJS). Enormous polyps of the transverse colon intussuscepting into the rectum turned out to be the rate cause of overflow incontinence. Although she presented all the signs of PJS at infancy, diagnosis was made only after a period of nine years, implying a lack of follow-up. We emphasize that when polyps occur in children, a complete examination is required, and once the diagnosis of Peutz-Jeghers syndrome is established, frequent endoscopic follow-up and resection of polyps are necessary.

[Anal sphincter dysplasia as cause of chronic defecation disorders: a clinical and genetic study]. / Analsphinkterdysplasie als Ursache chronischer Defäkationsstörungen: eine klinische und genetische Studie.

Anal sphincter dysplasia is a congenital, often familial malformation of the anal canal. In the literature, the anomaly is poorly represented and usually referred to as anteriorly or ventrally displaced anus. The range of symptoms includes chronic constipation, severe straining at defecation, encopresis and chronic paradoxical diarrhea with fecal incontinence. One usually finds dysplasia and absent (type I) or incomplete (type II) fixation of the sphincter complex to the coccyx. Both are demonstrable by computerized tomography (CT) as well as by intraoperative dissection of the sphincter muscles. There ist also shortening of the ectodermal segment of the anal canal which is obviously responsible for the disturbed stool sensation. Posterior butterfly anoplasty combined with fixation of the sphincter complex to the coccyx usually leads to immediate improvement of defecation disorders. A genetic study on 42 patients (age 1-52 years) operated on for anal sphincter dysplasia revealed autosomal dominant inheritance with variable expression and probably incomplete penetrance of the mutated gene.

Implication of sex differences in the familial transmission of infantile autism.

There are studies suggesting possible hereditary influence in autism. Data on 102 autistic children, 78 boys and 24 girls, showed that there was a significantly greater proportion of autistic girls than boys with IQs less than 50 and with evidence of brain damage. The autistic girls also had a greater proportion of relatives affected with autism or cognitive-language deficit than did the boys. The implication of sex differences in the possible mode of familial transmission of autism is discussed.