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S W Moore

Publications and source records attributed to S W Moore.

At least 19 recordsLinked to original sources
PubMed2006

The contribution of associated congenital anomalies in understanding Hirschsprung's disease.

Hirschsprung's disease (HSCR) is a complex congenital disorder which, from a molecular perspective, appears to result due to disruption of normal signalling during development of enteric nerve cells, resulting in aganglionosis of the distal bowel. Associated congenital anomalies occur in at least 5-32% (mean 21%) of patients and certain syndromic phenotypes have been linked to distinct genetic sites, indicating underlying genetic associations of the disease and probable gene-gene interaction in its pathogenesis. Clear-cut associations with HSCR include Down's syndrome, dominant sensorineural deafness, Waardenburg syndrome, neurofibromatosis, neuroblastoma, phaeochromocytoma, the MEN type IIB syndrome and other abnormalities. Individual anomalies vary from 2.97% to 8%, the most frequent being the gastrointestinal tract (GIT) (8.05%), the central nervous system (CNS) and sensorineural anomalies (6.79%) and the genito-urinary tract (6.05%). Other associated systems include the musculoskeletal (5.12%), cardiovascular systems (4.99%), craniofacial and eye abnormalities (3%) and less frequently the skin and integumentary system (ectodermal dysplasia) and syndromes related to cholesterol and fat metabolism. In addition to associations with neuroblastoma and tumours related to MEN2B, HSCR may also be associated with tumours of neural origin such as ganglioneuroma, ganglioneuroblastoma, retinoblastoma and tumours associated with neurofibromatosis and other autonomic nervous system disturbances. The contribution of the major susceptibility genes on chromosome 10 (RET) and chromosome 13 (EDNRB) is well established in the phenotypic expression of HSCR. Whereas major RET mutations may result in HSCR by haploinsufficiency in 20-25% of cases, the etiology of the majority of sporadic HSCR is not as clear, appearing to arise from the combined cumulative effects of susceptibility loci at critical genes controlling the mechanisms of cell proliferation, differentiation and maturation. In addition, potential "modifying" associations exist with chromosome 2, 9, 20, 21 and 22, and we explore the importance of certain flanking genes of critical areas in the final phenotypic expression of HSCR.

Animals↗
PubMed2006

The peripheral anionic site of acetylcholinesterase: structure, functions and potential role in rational drug design.

The peripheral anionic site of acetylcholinesterase lies at the entrance to the active site gorge. It is composed of five residues (Tyr 70, Asp 72, Tyr 121, Trp 279 and Tyr 334; Torpedo numbering); associated with it are a number of surface loops, conferring a high degree of conformational flexibility on the area. The site is involved in the allosteric modulation of catalysis at the active centre and is the target of various anti-cholinesterases. It is also implicated in a number of non-classical functions, in particular, amyloid deposition, cell adhesion and neurite outgrowth. A number of peptide and protein ligands for the site have been identified. In this review, the structure and multiple functions of the peripheral anionic site are discussed, together with its potential as a target in rational drug design for the development of novel and improved inhibitors and of therapeutics for the treatment of neural cancers, nerve regeneration and neurodegenerative disorders such as Alzheimer's disease.

Acetylcholinesterase↗
PubMed2005

Acetylcholinesterase in Hirschsprung's disease.

The association between the congenital absence of colonic ganglion cells and an increased acetylcholinesterase (AChE) expression in the affected tissue is of diagnostic importance in Hirschsprung's disease (HSCR). Investigation of AChE's function in development may also help unravel some of the complex pathophysiology in HSCR. Normal nerves do not stain for AChE, but increased AChE expression is associated with the hypertrophied extrinsic nerve fibres of the aganglionic segment in HSCR. Although a high degree of histochemical diagnostic accuracy exists, results are not always uniform, and false positives and false negatives are reported. False negative results are primarily related to age, and an absence of AChE reaction does not exclude HSCR in neonates within the first 3 weeks after birth. AChE staining results may lack uniformity, resulting in a number of technical modifications that have been made to improve standardization of AChE staining. At least two distinct histological patterns are described, types A and B. The interpretation of increased AChE staining patterns in ganglionated bowel at the time of surgical pull-through remains a problem in patients with HSCR. The development of rapid staining techniques has helped to identify normal ganglionated bowel with greater certainty. The presence of fine AChE neurofibrils in the ganglionated segment has contributed to the debate surrounding intestinal neuronal dysplasia. Quantitative assay of cholinesterase activity confirms the pattern of histochemical staining. AChE is particularly increased in relation to butrylcholinesterase, with one molecular form, the G4 tetrameric form, predominating. It is likely that the raised levels of AChE in aganglionic tissue are the transcriptional consequence of the abnormalities in signalling molecules that characterize HSCR. Evidence suggests that this AChE is functioning in a nonenzymatic capacity to promote cell adhesion and differentiation and that the hypertrophied nerves and neurofibrils may be the result of this increased AChE expression.

Acetylcholinesterase↗
PubMed2003

The epidemiology of neonatal tumours. Report of an international working group.

Neonatal tumours occur every 12,500-27,500 live births and comprise 2% of childhood malignancies, but there is little clarity as to their real prevalence, sites of origin and pathological nature as reported series vary. As an entity, neonatal tumours provide a unique window of opportunity to study tumours in which minimal environmental interference has occurred. The majority of tumours present with a mass at birth (e.g., teratomas, neuroblastomas, mesoblastic nephroma, fibromatosis), which are not infrequently identified on antenatal ultrasound. Histologically, teratoma and neuroblastoma remain the two main tumour types encountered with soft tissue sarcoma, renal tumours, CNS tumours and leukaemia being the next most common tumour types identified. Malignant tumours are uncommon in the neonatal period per se and benign tumours may have malignant potential. A particular problem exists in clinical classification, as histological features of malignancy do not always correlate with clinical behaviour. Benign tumours may also be life threatening because of their size and location. Other tumours may demonstrate local invasiveness, but no metastatic potential, and tumours that are clearly malignant may demonstrate unpredictable or uncertain behaviour. Screening programmes have brought more tumours to light, but do not appear to affect the overall prognosis. They may provide clues to the stage at which tumours develop in foetu. The aetiology of cancer in children is multifactorial and includes both genetic and environmental factors. The association between congenital abnormalities and tumours is well established (15% of neonatal tumours). Genetic defects are highly likely in neonatal tumours and include those with a high risk of malignancy (e.g., retinoblastoma), but also genetically determined syndromes with an increased risk of malignancy and complex genetic rearrangements. Tumours are mostly genetically related at a cellular level and factors influencing cellular maturation or apoptosis within the developing foetus may continue to operate in the neonatal period. Cytogenetics of neonatal neoplasms appear to differ from neoplasms in older children, thus possibly explaining some of the observed differences in clinical behaviour. Certain constitutional chromosome anomalies, however, specifically favour tumours occurring in the foetal and neonatal period. In support of this hypothesis, certain cytogenetic anomalies appear to be specific to neonates, and a number of examples are explored. Other environmental associations include ionizing radiation, drugs taken during pregnancy, infections, tumours in the mother and environmental exposure.

Female↗
PubMed2003

Diagnostic aspects of cervical lymphadenopathy in children in the developing world: a study of 1,877 surgical specimens.

Chronic cervical lymphadenopathy is a common clinical problem frequently requiring surgical biopsy. To evaluate the characteristics of surgically excised cervical lymph nodes (LN) in children in a developing country, we studied 1,332 children less than 15 years old (1,877 surgically removed cervical LNs) over a 23-year period (1976-1999). Indications for biopsy included failure to respond to antibiotic therapy, rapid increase in size, hard, matted LNs in the preauricular, supraclavicular, and posterior triangle of the neck, and difficulty in diagnosis. Clinical and pathological characteristics investigated included age, malignancy, and granulomatous disease such as tuberculosis (tbc). The mean age was 7 years (tbc 5.8/neoplastic disease 8.5 years). Twenty LNs (1.5%) were histologically normal. There were 637 (47.8%) with nonspecific reactive lymphoid hyperplasia and 484 with chronic granulomatous changes (36.3%). Tuberculous lymphadenitis was confirmed in 332 of these (25%). In 181 (54.5%) Mycobacterium tuberculosis was cultured and a further 149 had acid-fast bacilli. Other granulomatous diseases identified included sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfmann disease) (3), syphilis (4), yaws (2), and toxoplasmosis (1). No mycobacteria other than M. tuberculosis were encountered. More than two-thirds (108) of 154 patients with neoplastic LN involvement had a lymphoma; in a further 10 lymphadenopathy was associated with leukemia. Pyogenic organisms were identified in 32, and 5 were positive for human immunodeficiency virus, 1 of whom had Kaposi's sarcoma. A second pathology was identified in 18 of the 637 cases of reactive lymphoid hyperplasia (3 with tuberculosis); in 15 (1.3%) a diagnosis of lymphoma was made from other sites (pleural fluid, etc.) within 6 months of initial biopsy. This represents a diagnostically difficult subgroup requiring further investigation. Chronic lymphadenopathy in children in developing countries has a high incidence of infective causes, including a significant incidence of M. tuberculosis. The incidence of serious pathology in more than one-half of the cervical LNs examined justifies aggressive surgical investigation.

Biopsy, Needle↗
PubMed2003

Significance of novel endothelin-B receptor gene polymorphisms in Hirschsprung's disease: predominance of a novel variant (561C/T) in patients with co-existing Down's syndrome.

Several genes have been implicated in the pathogenesis of Hirschsprung's disease (HSCR). In a previous study performed, five novel (V202M, E480K, IVS10-2A/G, D771N, IVS19-9C/T) mutations and one previously described mutation (P937L) have been identified in the RET proto-oncogene in 20% of the study population. To further investigate the involvement of other genes, mutation analysis of the endothelin-B receptor (EDNRB) gene was performed in 52 unrelated sporadic HSCR patients, including 38 non-syndromic and 14 patients with HSCR and Down's syndrome. Six novel (178G/A, 552C/T, 561C/T, 702C/T, IVS3-6C/T and IVS4 + 3A/G) sequence variants and one previously described (831G/A) polymorphism were identified. Statistically significant differences were achieved for six (178G/A, 552C/T, 561C/T, 702C/T, IVS3-6C/T and 831G/A) of these variants. The T-allele of the 561C/T polymorphism was over represented in the HSCR/Down's syndrome patient group (36% representing 5 of 14) compared to normal controls (6% representing 5 of 84) (p < 0.002, chi(2) with Yates correction = 12.14), suggesting that the 561C/T variant is associated with a low penetrance effect in patients with this complex phenotype. Detection of the 178G/A polymorphism in only non-syndromic HSCR patients, provide further support for an important role of specific sequence variants in the EDNRB gene in the HSCR/Down's syndrome phenotype.

Down Syndrome↗
PubMed2002

Non-familial visceral myopathy: clinical and pathologic features of degenerative leiomyopathy.

Degenerative leiomyopathy (DL) is a distinctive form of acquired degenerative visceral myopathy of uncertain etiology that occurs largely in Africa and results in intestinal pseudo-obstruction (IP). In this review of 39 patients from the Western Cape region of South Africa, the mean age at presentation was 9.5 years (range 6 months to 16 years). Characteristic clinical features included a chronic, insidious history of repeated attacks of abdominal distension, abdominal pain, and vomiting. Marked gaseous distension with atony and IP, especially of the colon, was noted on X-ray films. Megacolon was the most common radiologic feature, but pseudo-obstruction extended proximally into the small intestine in some patients with advanced disease. In the majority of cases the condition was progressive and eventually affected the entire gastrointestinal (GI) tract.

Abdominal Pain↗
PubMed2002

Unusual variations of gastrointestinal smooth muscle abnormalities associated with chronic intestinal pseudo-obstruction.

The clinicopathological spectrum of gastrointestinal (GI) smooth-muscle abnormalities associated with chronic intestinal pseudo-obstruction (CIPO) includes numerous heterogeneous conditions that are often ill-defined and poorly understood. Primary GI smooth-muscle abnormalities include familial and sporadic forms. Secondary involvement of GI smooth-muscle may result from associated GI and systemic conditions, but is less frequent than in adults. This study documents the clinicopathological findings observed in 12 South African patients with unusual forms of visceral smooth-muscle abnormalities not conforming to the diagnostic criteria of known primary visceral myopathies at the Tygerberg and Red Cross Childrens' Hospitals over a 14-year period (July 1985 through January 1999). Congenital muscle defects occurred in 5 patients where layers of bowel-wall muscle were absent or attenuated. Idiopathic fibrosis and ultrastructural features of perinuclear and mitochondrial vacuolisation were noted in 2 patients. A 21-year-old female with long-standing pseudo-obstruction demonstrated diminished immunohistochemical expression of enteric alpha-smooth-muscle actin without associated muscular degeneration or fibrosis. A secondary complication of dermatomyositis (bowel perforation) occurred twice in 1 patient. In 3 further patients (1 each with anorectal malformation, long-segment Hirschsprung's disease, and intestinal neuronal dysplasia), muscle fibrosis appeared during progression of the pre-existing disease. Visceral myopathies are poorly understood conditions that may present with CIPO. Unusual variations occur that do not conform to the usual recognised histological patterns. Secondary involvement may also be more common than anticipated in children. The challenge to further understanding these uncommon conditions lies in timely diagnosis and identification of early, subtle signs. Optimal and extensive application of various diagnostic modalities, including the development of new diagnostic tools, is of considerable importance in identifying hitherto unexplained CIPO due to GI smooth-muscle abnormalities.

Adolescent↗
PubMed2001

Diagnostic dilemmas in abdominal tuberculosis in children.

The authors review 45 pediatric patients with intra-abdominal tuberculosis (ATB) treated between May 1990 and April 1998. The diagnosis was confirmed histologically or by positive culture for Mycobacterium tuberculosis. Clinical presentation was with an abdominal mass (12), subacute obstruction (11), ascites (5), mass and ascites (4), peritonitis (4), and 9 unusual presentations. Mantoux tests were positive in 68% of patients tested. There were radiologic features suggestive of pulmonary TB in 29 patients (64%); abnormal abdominal radiographs were recorded in 21 (47%). Lymphadenopathy was noted on abdominal ultrasound in 23 of 30 patients (77%) and on computed tomography scan in a further 3 of 8 patients investigated. Ascitic fluid adenosine deaminase (ADA) levels were greater than 30 IU/l in 3 of 4 patients (75%), suggesting ATB. All 28 patients screened for human immunodeficiency virus were negative. A surgical procedure was performed in 39 patients. 29 (74%) had an elective diagnostic laparotomy for tissue diagnosis. One (3.4%) developed a postoperative intra-abdominal abscess. Ten (26%) presented with complications requiring surgical intervention including perforated viscus, segmental bowel resection, strictureplasty, adhesiolysis, or ileostomy. One of the latter died due to sepsis after having complications of persistent intestinal obstruction and cecal perforation. The authors recommend an aggressive approach to patients with suspected ATB in order to obtain an early definitive diagnosis, prevent complications, and reduce morbidity and mortality. They emphasize the importance of tissue diagnosis and confirmation by culture.

Abdominal Abscess↗
PubMed2001

Association of the HNK-1 epitope with the detergent-soluble G4 isoform of acetylcholinesterase from human neuroblastoma cells.

The HNK-1 carbohydrate epitope is expressed in neural and natural killer cells and is a mediator of cell adhesion. It is well documented that acetylcholinesterase has a secondary function in cell adhesion and differentiation. The presence of HNK-1 on isoforms of Torpedo and Electrophorus acetylcholinesterase, as well as isoforms from the bovine central nervous system has been described. In this paper, we have investigated the association of the epitope with acetylcholinesterase from human neuroblastoma cells. Acetylcholinesterase was extracted, with or without detergent, purified on immunoaffinity columns and the isoforms separated by sucrose density gradient sedimentation. Secreted acetylcholinesterase, from spent serum-free culture medium, was similarly treated. The presence of the HNK-1 epitope was determined by ELISA using the anti-HNK-1 and Elec 39 monoclonal antibodies. The epitope was found to be associated with the detergent-soluble G4 isoform, but not with the hydrophilic G1 nor the secreted hydrophilic G4 isoforms. Likewise, no HNK-1 was observed associated with human erythrocyte acetylcholinesterase. These results indicate that acetylcholinesterase-G4, anchored in the extracellular membrane, is capable of mediating cell-substrate adhesion through HNK-1.

Acetylcholinesterase↗
PubMed2001

Novel RET mutations in Hirschsprung's disease patients from the diverse South African population.

Hirschsprung's disease (HSCR) is a common cause of intestinal obstruction in neonates with an incidence of one in 5000 live births. The disease occurs due to the absence of parasympathetic neuronal ganglia in the hindgut, resulting in irregular or sustained contraction of the affected segment. DNA samples of 40 unrelated subjects with HSCR were subjected to mutation screening of the RET (REarranged during Transfection) proto-oncogene, the major susceptibility gene for HSCR. Five novel (V202M, E480K, IVS10-2A/G, D771N, IVS19-9C/T) and one previously described mutation (P973L) were identified. Only two of the mutation-positive patients (from different ethnic groups) displayed total colonic aganglionosis, and both were heterozygous for mutation D771N. The potential disease-causing mutations occurred in 20% of individuals, with more males (22.5% representing seven of 31 males) affected than females (12.5% representing one of eight females). This study represents the first comprehensive genetic analysis of this disease in the diverse South African population.

Black People↗
PubMed2001

Clinicopathological features of Meckel's diverticula in 32 patients, with emphasis on the presence of Helicobacter pylori.

Meckel's diverticula (MD) with areas of gastric heterotopia (metaplasia) are more likely to become symptomatic than those that contain mucosa of purely an intestinal type. Helicobacter pylori has been associated with the pathogenesis of various diseases. The aim of the study was to evaluate whether H. pylori could be identified within metaplastic gastric mucosa in MD. A retrospective evaluation of the histopathological features and the clinical presentation of patients with MD was undertaken. The study group included 32 cases (20 paediatric and 12 adults). The commonest modes of presentation were acute pain (25%), obstruction (19%), bleeding (12.5%) and hernias (9%). On histological examination, heterotopic gastric mucosa was noted to be present in 12 cases. Of these, 3 specimens were noted to have H. pylori organisms present using a specific immunostaining technique. Two patients had concurrent gastric biopsies; one stained positively for H. pylori but the second (1 mm biopsy) was rapid urease-test positive only. In conclusion, the study provides strong evidence that H. pylori may colonise heterotopic gastric mucosa in a minority of MD. H. pylori is apparently not involved in the pathogenesis of most cases of complicated MD. Nonetheless, all 3 patients who had evidence of H. pylori were symptomatic.

Adolescent↗
PubMed2000

Cholinesterases modulate cell adhesion in human neuroblastoma cells in vitro.

Cholinesterases are expressed non-synaptically during embryonic development, neoplasia and neurodegeneration. We have investigated the effects of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and, conversely, anti-AChE and -BChE antibodies and inhibitors on cell adhesion and neurite outgrowth in human neuroblastoma cells. Analysis of cholinesterase levels and isoforms in undifferentiated and differentiated cells indicated a significant rise in AChE levels on differentiation. This increase was related to both cell-associated and secreted enzyme, and was predominantly the G4 isoform. BChE levels and isoforms, on the other hand, showed no significant variation. Coating the tissue culture plate with AChE stimulated neurite outgrowth, while BChE had an anti-adhesive effect. Cell adhesion was affected by the BChE inhibitor, ethopropazine, and the AChE peripheral site inhibitor, BW284c51, but not by eserine which binds to the active site. This indicates that the adhesion function is non-cholinergic, a finding supported by the lack of effect of AE-2, a monoclonal antibody that inhibits AChE, on cell adhesion. Four out of a panel of nine anti-AChE antibodies inhibited adhesion to varying degrees. Of these antibodies, two are catalytic, with epitopes associated with the peripheral anionic site of AChE, and the remaining two have epitopes overlapping this site. Neither of the two anti-BChE antibodies used had any effect on adhesion. These results indicate the importance of AChE in neuroblastoma cell adhesion and neurite outgrowth, and suggest that the peripheral anionic site may be involved in these processes.

Acetylcholinesterase↗
PubMed2000

Elevated tissue immunoglobulins in Hirschsprung's disease--indication of early immunologic response.

Hirschsprung's disease is of multifactorial origin including genetic as well as other region-specific neuroenvironmental factors as well as focal contact with the extracellular matrix. Immunological activity is elevated in patients with enterocolitis associated with Hirschsprung's disease suggesting an immunological role in HD. Increased expression of major histocompatibility complexes (MHC) class II antigens and ICAM-1 in the aganglionic segments of bowel further strengthen this association and suggest early immunologic involvement. In this study, immunoglobulin activity was biochemically assessed in surgically resected specimens of 23 patients with Hirschsprung's disease in whom there was no clinical or histological evidence of enterocolitis. IgG and IgM were significantly increased in segments of bowel histologically identified as aganglionic or transitional zone, suggesting an area of maximal immunological activity in the transitional zone. The lack of an increase in IgA immunoglobulin activity in the same bowel segments suggests that IgA response may be related to associated enterocolitis in HD. Elevated tissue IgG and IgM levels were observed in 5 neonates presenting within the first week of life and older patients did not have significantly higher immunoglobulin levels, suggesting that the immunological response was not part of an ongoing infection or progressive condition. Increased IgM in the neonatal period suggests an early immune response in Hirschsprung's disease and strengthens the hypothesis that the immune system may be involved in its pathogenesis. Possible causes include the effects of an antenatal infection or local microenvironmental influences on the differentiation or maturation of migrating neuroblasts of the enteric nervous system.

Age Factors↗
PubMed1999

The adhesion function on acetylcholinesterase is located at the peripheral anionic site.

There is accumulating evidence that acetylcholinesterase has secondary noncholinergic functions, related to adhesion, differentiation, and the deposition of beta-amyloid in Alzheimer's disease. We have observed that the specific acetylcholinesterase peripheral anionic site inhibitors, BW284c51 and propidium iodide, abrogated cell-substrate adhesion in three human neuroblastoma cell lines. The active-site inhibitors, eserine and edrophonium, in contrast, had no effect. Certain anti-AChE antibodies were also shown to inhibit adhesion. Of these, the most effective were a monoclonal (E8) and a polyclonal having cholinesterase-like catalytic activity. These were raised against an acetylcholinesterase-inhibitor complex, implying that the epitope is associated with active-site structures. Two other monoclonal antibodies (E62A1 and E65E8) partially inhibited adhesion. The epitopes of these antibodies have been shown to overlap the peripheral anionic site of acetylcholinesterase. Competition ELISA between the monoclonal antibodies and inhibitors indicated competition between E8, E62A1, and E65E8 and the peripheral-site inhibitors BW284c51 and propidium, but not with the active-site inhibitors eserine and edrophonium. Fluorescence titration between antibodies and propidium confirmed these results. We conclude that the adhesion function of acetylcholinesterase is located at the peripheral anionic site. This has implications, not only for our understanding of neural development and its disorders, but also for the treatment of neuroblastoma, the leukemias, and Alzheimer's disease.

Acetylcholinesterase↗
PubMed1998

Fulminanting necrotising enterocolitis: outcome and prognostic factors.

In order to determine the outcome of infants with fulminant necrotising entercolitis (NEC), the records of 128 surgically-treated neonates were reviewed. Fifty-two were found to have severe, rapid-onset disease. The 30-day survival was determined and correlated with birth weight, gestational age, laboratory and radiological findings, and extent of disease. Seven patients did not respond to resuscitative measures and were treated by percutaneous drainage with a uniformly fatal outcome. For patients who could be made fit for surgery, the only absolute predictor of survival was extent of disease. Pan-necrosis occurred in 19 patients and all of these died. Conversely, patients who had resectable disease had a 30-day survival of 61%. Pan-necrosis could not be determined preoperatively by radiological findings. Patients with severe, rapid-onset NEC and evidence of gangrene who respond to resuscitation should have active surgical management, as approximately one-half of them have resectable disease and a reasonable short-term outcome may be expected. Patients who do not respond to resuscitative measures and those with a surgical finding of pan-necrosis had a uniformly fatal outcome in this study, and if resources are limited, it is reasonable to withdraw active management in this group of patients.

Analysis of Variance↗
PubMed1998

Hirschsprung's disease: genetic and functional associations of Down's and Waardenburg syndromes.

Despite significant advances in understanding the genetic background in Hirschsprung's disease (HD), the majority of cases are believed to be multigenic and multifactorial. Conditions associated with an increased risk of HD suggest some common inherited factor and include Down's syndrome, Waardenburg syndrome (WS), dominant sensorineural deafness, neurofibromatosis, neuroblastoma, phaechromocytoma, the MEN type 2B syndrome, and other abnormalities. The reported incidence of Down's syndrome in HD is approximately 2%, but the range varies from 2% to 15%. WS, on the other hand, is one of a number of uncommon human conditions in which pigmentary disturbances are associated with sensorineural deafness. HD mutations have been mapped to a number of genes, i.e., RET proto-oncogene, at 10q11.2; the recessive EDNRB gene, located at 13q22; its ligand endothelin 3 (EDN3); and the glial cell line-derived neurotrophic factor (GDNF) in humans. Mutations of known genes appear to account for only a relatively small number of HD cases (20% in the case of RET). GDNF may modulate the disease phenotype by interacting with other susceptibility loci (e.g., RET). The genetic aspects of HD occurring in association with trisomy 21 and WS are reviewed. Clinical presentation, diagnosis, treatment and long-term outcome in this patient group are evaluated. Additional data are presented on 12 children with Down's syndrome out of 408 surgically treated HD patients. The role of associated anomalies is evaluated, and an increased susceptibility to severe enterocolitis associated with a high mortality rate is reported. Surgical correction can be achieved, but patients may require some form of ongoing help to facilitate acceptable bowel function. The decision as to the nature and timing of the surgical correction must be individualized.

Down Syndrome↗