Nurture Early for Optimal Nutrition (NEON) participatory learning and action women's groups to improve infant feeding and practices in South Asian infants: pilot randomised trial study protocol

INTRODUCTION

Feeding practices developed in early life can impact a child's nutrition, growth, dental health, cognitive development and lifetime risk of chronic diseases. Substantial evidence suggests ethnic health inequalities, and non-recommended complementary infant feeding practices among UK's South Asian (SA) population. Nurture Early for Optimal Nutrition aims to use women's group participatory learning and action (PLA) cycles to optimise infant feeding, care and dental hygiene practices in SA infants <2 years in East London.

METHODS AND ANALYSIS

A three-arm pilot feasibility cluster randomised controlled trial will assess feasibility, acceptability, costs and explore preliminary effectiveness for proposed primary outcome (ie, reporting on body mass index (BMI) z-score). Multilingual SA community facilitators will deliver the intervention, group PLA Cycle, to mothers/carers in respective ethnic/language groups. 12 wards are randomised to face-to-face PLA, online PLA and usual care arms in 1:1:1 ratio. Primary outcomes are feasibility and process measures (ie, BMI z-score, study records, feedback questionnaires, direct observation of intervention and sustainability) for assessment against Go/Stop criteria. Secondary outcomes are cluster-level and economic outcomes (ie, eating behaviour, parental feeding practices, network diffusion, children development performance, level of dental caries, general practitioner utilisation, costs, staff time). Outcomes are measured at baseline, every 2 weeks during intervention, 14 weeks and at 6 months by blinded outcome assessors where possible. This study will use concurrent mixed-methods evaluation. Quantitative analyses include descriptive summary with 95% CI and sample size calculation for the definitive trial. The intervention effect with CI will be estimated for child BMI z-score. Implementation will be evaluated qualitatively using thematic framework analysis.

ETHICS AND DISSEMINATION

Ethics approval was obtained from University College London (UCL), National Health Service (Health Research Authority (HRA) and Health and Care Research Wales (HRCW)). Results will be published in peer-reviewed journals, presented at scientific conferences/workshops with commissioners, partners and participating communities. Plain language summaries will be disseminated through community groups, websites and social media.

TRIAL REGISTRATION NUMBER

IRAS-ID-296259 (ISRCTN10234623).

Paediatric survivors beyond infancy with Stüve-Wiedemann syndrome - A case series from the West Midlands, UK

Stüve-Wiedemann Syndrome (STWS) is an autosomal recessive condition caused by variants in the LIFR gene, presenting with respiratory failure, hyperthermia and skeletal dysplasia in the neonatal period. Historically identified as a lethal condition, more children are now managed holistically from early in life with multidisciplinary team involvement with improved outcomes. This stems from early diagnosis, supported by molecular testing in the pre and postnatal periods. This report includes five such cases with survival in childhood to 10 years old in the UK affected by skeletal abnormalities, hyperthermia, respiratory distress and their diagnostic odyssey. All cases have a molecular diagnosis; two patients (family 1) were found to be homozygous for a novel pathogenic LIFR variant NM_002310.5:c.704G > A, p.(Trp235Ter). One patient (family 2) is compound heterozygous with the previously reported LIFR variant NM_002310.5:c.756dup p.(Lys253Ter), and a second novel variant NM_002310.5:c.397+5G > A. Two patients (family 3) are homozygous for one of the same LIFR variants NM_002310.5:c.756dup p.(Lys253Ter) as in family 2. This report discusses genotypic and phenotypic data for five patients with STWS, as well as the need for multi-disciplinary, proactive management and genetic counselling.

Mechanism of KMT5B haploinsufficiency in neurodevelopment in humans and mice

Pathogenic variants in KMT5B, a lysine methyltransferase, are associated with global developmental delay, macrocephaly, autism, and congenital anomalies (OMIM# 617788). Given the relatively recent discovery of this disorder, it has not been fully characterized. Deep phenotyping of the largest (n = 43) patient cohort to date identified that hypotonia and congenital heart defects are prominent features that were previously not associated with this syndrome. Both missense variants and putative loss-of-function variants resulted in slow growth in patient-derived cell lines. KMT5B homozygous knockout mice were smaller in size than their wild-type littermates but did not have significantly smaller brains, suggesting relative macrocephaly, also noted as a prominent clinical feature. RNA sequencing of patient lymphoblasts and Kmt5b haploinsufficient mouse brains identified differentially expressed pathways associated with nervous system development and function including axon guidance signaling. Overall, we identified additional pathogenic variants and clinical features in KMT5B-related neurodevelopmental disorder and provide insights into the molecular mechanisms of the disorder using multiple model systems.

Exome sequencing efficacy and phenotypic expansions involving esophageal atresia/tracheoesophageal fistula plus

Esophageal atresia/tracheoesophageal fistula (EA/TEF) is a life-threatening birth defect that often occurs with other major birth defects (EA/TEF+). Despite advances in genetic testing, a molecular diagnosis can only be made in a minority of EA/TEF+ cases. Here, we analyzed clinical exome sequencing data and data from the DECIPHER database to determine the efficacy of exome sequencing in cases of EA/TEF+ and to identify phenotypic expansions involving EA/TEF. Among 67 individuals with EA/TEF+ referred for clinical exome sequencing, a definitive or probable diagnosis was made in 11 cases for an efficacy rate of 16% (11/67). This efficacy rate is significantly lower than that reported for other major birth defects, suggesting that polygenic, multifactorial, epigenetic, and/or environmental factors may play a particularly important role in EA/TEF pathogenesis. Our cohort included individuals with pathogenic or likely pathogenic variants that affect TCF4 and its downstream target NRXN1, and FANCA, FANCB, and FANCC, which are associated with Fanconi anemia. These cases, previously published case reports, and comparisons to other EA/TEF genes made using a machine learning algorithm, provide evidence in support of a potential pathogenic role for these genes in the development of EA/TEF.

Monoallelic variants resulting in substitutions of MAB21L1 Arg51 Cause Aniridia and microphthalmia

Classical aniridia is a congenital and progressive panocular disorder almost exclusively caused by heterozygous loss-of-function variants at the PAX6 locus. We report nine individuals from five families with severe aniridia and/or microphthalmia (with no detectable PAX6 mutation) with ultrarare monoallelic missense variants altering the Arg51 codon of MAB21L1. These mutations occurred de novo in 3/5 families, with the remaining families being compatible with autosomal dominant inheritance. Mice engineered to carry the p.Arg51Leu change showed a highly-penetrant optic disc anomaly in heterozygous animals with severe microphthalmia in homozygotes. Substitutions of the same codon (Arg51) in MAB21L2, a close homolog of MAB21L1, cause severe ocular and skeletal malformations in humans and mice. The predicted nucleotidyltransferase function of MAB21L1 could not be demonstrated using purified protein with a variety of nucleotide substrates and oligonucleotide activators. Induced expression of GFP-tagged wildtype and mutant MAB21L1 in human cells caused only modest transcriptional changes. Mass spectrometry of immunoprecipitated protein revealed that both mutant and wildtype MAB21L1 associate with transcription factors that are known regulators of PAX6 (MEIS1, MEIS2 and PBX1) and with poly(A) RNA binding proteins. Arg51 substitutions reduce the association of wild-type MAB21L1 with TBL1XR1, a component of the NCoR complex. We found limited evidence for mutation-specific interactions with MSI2/Musashi-2, an RNA-binding proteins with effects on many different developmental pathways. Given that biallelic loss-of-function variants in MAB21L1 result in a milder eye phenotype we suggest that Arg51-altering monoallelic variants most plausibly perturb eye development via a gain-of-function mechanism.

Developing a community facilitator-led participatory learning and action women's group intervention to improve infant feeding, care and dental hygiene practices in South Asian infants: NEON programme

INTRODUCTION

The Nurture Early for Optimal Nutrition (NEON) study is a multiphase project that aims to optimize feeding, care and dental hygiene practices in South Asian children <2 years in East London, United Kingdom. The multiphase project uses a participatory learning and action (PLA) approach facilitated by a multilingual community facilitator. In this paper, we elaborate on the process and results of the Intervention Development Phase in the context of the wider NEON programme.

METHODS

Qualitative community-based participatory intervention codevelopment and adaptation.

SETTING

Community centres in East London and online (Zoom) meetings and workshops.

PARTICIPANTS

In total, 32 participants registered to participate in the Intervention Development Phase. Four Intervention Development workshops were held, attended by 25, 17, 20 and 20 participants, respectively.

RESULTS

Collaboratively, a culturally sensitive NEON intervention package was developed consisting of (1) PLA group facilitator manual, (2) picture cards detailing recommended and nonrecommended feeding, care and dental hygiene practices with facilitators/barriers to uptake as well as solutions to address these, (3) healthy infant cultural recipes, (4) participatory Community Asset Maps and (5) list of resources and services supporting infant feeding, care and dental hygiene practices.

CONCLUSION

The Intervention Development Phase of the NEON programme demonstrates the value of a collaborative approach between researchers, community facilitators and the target population when developing public health interventions. We recommend that interventions to promote infant feeding, care and dental hygiene practices should be codeveloped with communities. Recognizing and taking into account both social and cultural norms may be of particular value for infants from ethnically diverse communities to develop interventions that are both effective in and accepted by these communities.

PATIENT AND PUBLIC INVOLVEMENT AND ENGAGEMENT

Considerable efforts were placed on Patient/Participant and Public Involvement and Engagement. Five community facilitators were identified, each of which represented one ethnic/language group: (i) Bangladeshi/Bengali and Sylheti, (ii) Pakistani/Urdu, (iii) Indian/Gujrati, (iv) Indian/Punjabi and (v) Sri Lankan/Tamil. The community facilitators were engaged in every step of the study, from the initial drafting of the protocol and study design to the Intervention Development and refinement of the NEON toolkit, as well as the publication and dissemination of the study findings. More specifically, their role in the Intervention Development Phase of the NEON programme was to: 1. Support the development of the study protocol, information sheets and ethics application. 2. Ensure any documents intended for community members are clear, appropriate and sensitively worded. 3. Develop strategies to troubleshoot any logistical challenges of project delivery, for example, recruitment shortfalls. 4. Contribute to the writing of academic papers, in particular reviewing and revising drafts. 5. Develop plain language summaries and assist in dissemination activities, for example, updates on relevant websites. 6. Contribute to the development of the NEON intervention toolkit and recruitment of the community members. 7. Attend and contribute to Intervention Development workshops, ensuring the participant's voices were the focus of the discussion and workshop outcomes.

Bi-allelic Loss-of-Function CACNA1B Mutations in Progressive Epilepsy-Dyskinesia

The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Ca_v2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca²⁺ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Ca_v2.2 in normal human neurodevelopment.

Angelman Syndrome due to a Maternally Inherited Intragenic Deletion Encompassing Exons 7 and 8 of the UBE3A Gene

Angelman syndrome (AS) is characterised by developmental delay, lack of speech, seizures, a characteristic behavioural profile with a happy demeanour, microcephaly, and ataxia. More than two-thirds of cases are due to an approximately 5-Mb interstitial deletion of the imprinted region 15q11.2q13, which is usually de novo. The rest are associated with point mutations in the UBE3A gene, imprinting defects, and paternal uniparental disomy. Small intragenic UBE3A deletions have rarely been described. They are usually maternally inherited, increasing the recurrence risk to 50%, and may be missed by conventional testing (methylation studies and UBE3A gene sequencing). We describe a boy with AS due to an 11.7-kb intragenic deletion. The deletion was identified by array-CGH and was subsequently detected in his affected first cousin and unaffected maternal grandfather, mother, and aunt, confirming the silencing of the paternal allele. The patient had developmental delay, speech impairment, a happy demeanour, microcephaly, and an abnormal EEG, but no seizures by the age of 4 years. Delineation of the underlying genetic mechanism is of utmost importance for reasons of genetic counselling, as well as appropriate management and prognosis. Alternative techniques, such as array-CGH and MLPA, are necessary when conventional testing for AS has failed to identify the underlying genetic mechanism.

Genetic Analysis of 'PAX6-Negative' Individuals with Aniridia or Gillespie Syndrome

We report molecular genetic analysis of 42 affected individuals referred with a diagnosis of aniridia who previously screened as negative for intragenic PAX6 mutations. Of these 42, the diagnoses were 31 individuals with aniridia and 11 individuals referred with a diagnosis of Gillespie syndrome (iris hypoplasia, ataxia and mild to moderate developmental delay). Array-based comparative genomic hybridization identified six whole gene deletions: four encompassing PAX6 and two encompassing FOXC1. Six deletions with plausible cis-regulatory effects were identified: five that were 3' (telomeric) to PAX6 and one within a gene desert 5' (telomeric) to PITX2. Sequence analysis of the FOXC1 and PITX2 coding regions identified two plausibly pathogenic de novo FOXC1 missense mutations (p.Pro79Thr and p.Leu101Pro). No intragenic mutations were detected in PITX2. FISH mapping in an individual with Gillespie-like syndrome with an apparently balanced X;11 reciprocal translocation revealed disruption of a gene at each breakpoint: ARHGAP6 on the X chromosome and PHF21A on chromosome 11. In the other individuals with Gillespie syndrome no mutations were identified in either of these genes, or in HCCS which lies close to the Xp breakpoint. Disruption of PHF21A has previously been implicated in the causation of intellectual disability (but not aniridia). Plausibly causative mutations were identified in 15 out of 42 individuals (12/32 aniridia; 3/11 Gillespie syndrome). Fourteen of these mutations presented in the known aniridia genes; PAX6, FOXC1 and PITX2. The large number of individuals in the cohort with no mutation identified suggests greater locus heterogeneity may exist in both isolated and syndromic aniridia than was previously appreciated.

A combined vascular surgical and clinical genetics approach to diffuse aneurysmal disease

We report two patients who presented with extensive aneurysmal disease, in association with minimal external physical signs. Patient 1 remained genetically undiagnosed despite multiple structural, biochemical and genetic investigations. He made a good recovery following surgery for popliteal and left axillary artery aneurysms. Patient 2 was diagnosed with vascular type Ehlers-Danlos syndrome, associated with a high degree of tissue and blood vessel fragility, and is being managed conservatively. Early multidisciplinary assessment of such patients facilitates accurate diagnosis and management.

Mutation of SALL2 causes recessive ocular coloboma in humans and mice

Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice.

A novel heterozygous SOX2 mutation causing congenital bilateral anophthalmia, hypogonadotropic hypogonadism and growth hormone deficiency

Heterozygous de novo mutations in SOX2 have been reported in approximately 10-20% of patients with unilateral or bilateral anophthalmia or microphthalmia. An additional phenotype of hypopituitarism, with anterior pituitary hypoplasia and hypogonadotropic hypogonadism, has been reported in patients carrying SOX2 alterations. We report a novel heterozygous mutation in the SOX2 gene in a male affected with congenital bilateral anophthalmia, hypogonadotrophic hypogonadism and growth hormone deficiency. The mutation we describe is a cytosine deletion in position 905 (c905delC) which causes frameshift and an aberrant C-terminal domain. Our report highlights the fact that subjects affected with eye anomalies and harboring SOX2 mutations are at high risk for gonadotropin deficiency, which has important implications for their clinical management.

CHRNG genotype-phenotype correlations in the multiple pterygium syndromes

BACKGROUND

Germline mutations in the CHRNG gene that encodes the γ subunit of the embryonal acetylcholine receptor may cause the non-lethal Escobar variant (EVMPS) or the lethal form (LMPS) of multiple pterygium syndrome (MPS). In addition CHRNG mutations and mutations in other components of the embryonal acetylcholine receptor may present with fetal akinesia deformation sequence (FADS) without pterygia.

METHODS

In order to elucidate further the role of CHRNG mutations in MPS/FADS, this study evaluated the results of CHRNG mutation analysis in 100 families with a clinical diagnosis of MPS/FADS.

RESULTS

CHRNG mutations were identified in 11/41 (27%) of families with EVMPS and 5/59 (8%) with LMPS/FADS. Most patients with a detectable CHRNG mutation (21 of 24 (87.5%)) had pterygia but no CHRNG mutations were detected in the presence of central nervous system anomalies.

DISCUSSION

The mutation spectrum was similar in EVMPS and LMPS/FADS kindreds and EVMPS and LMPS phenotypes were observed in different families with the same CHRNG mutation. Despite this intrafamilial variability, it is estimated that there is a 95% chance that a subsequent sibling will have the same MPS phenotype (EVMPS or LMPS) as the proband (though concordance is less for more distant relatives). Based on these findings, a molecular genetic diagnostic pathway for the investigation of MPS/FADS is proposed.

Digenic inheritance of mutations in FOXC1 and PITX2 : correlating transcription factor function and Axenfeld-Rieger disease severity

Disease-causing mutations affecting either one of the transcription factor genes, PITX2 or FOXC1, have been previously identified in patients with Axenfeld-Rieger syndrome (AR). We identified a family who segregate novel mutations in both PITX2 (p.Ser233Leu) and FOXC1 (c.609delC). The most severely affected individual, who presented with an atypical phenotype of corneal opacification, lens extrusion, persistent hyperplastic primary vitreous (PHPV), and subsequent bilateral retinal detachment, inherited mutations in both genes, whereas the single heterozygous mutations caused mild AR phenotypes. This is the first report of such digenic inheritance. By analyzing cognate targets of each gene, we showed that FOXC1 and PITX2 can independently regulate their own and each other's target gene promoters and do not show synergistic action in vitro. Mutation in either gene caused reduced transcriptional activation to different extents on the FOXO1 and PLOD1 promoters, whereas both mutations in combination showed the lowest level of activation. These data show how the compensatory activity of one factor, when the other is impaired, may lessen the phenotypic impact of developmental anomalies, yet reduced activity of both transcription factors increased disease severity. This suggests an under-reported mechanism for phenotypic variability whereby single mutations cause mild AR phenotypes, whereas digenic inheritance increases phenotypic severity.

Chromosome abnormalities and the genetics of congenital corneal opacification

Congenital corneal opacification (CCO) encompasses a broad spectrum of disorders that have different etiologies, including genetic and environmental. Terminology used in clinical phenotyping is commonly not specific enough to describe separate entities, for example both the terms Peters anomaly and sclerocornea have been ascribed to a clinical picture of total CCO, without investigating the presence or absence of iridocorneal adhesions. This is not only confusing but also unhelpful in determining valid genotype-phenotype correlations, and thereby revealing clues for pathogenesis. We undertook a systematic review of the literature focusing on CCO as part of anterior segment developmental anomalies (ASDA), and analyzed its association specifically with chromosomal abnormalities. Genes previously identified as being associated with CCO are also summarized. All reports were critically appraised to classify phenotypes according to described features, rather than the given diagnosis. Some interesting associations were found, and are discussed.

Evidence for genetic heterogeneity in D-2-hydroxyglutaric aciduria

We performed molecular, enzyme, and metabolic studies in 50 patients with D-2-hydroxyglutaric aciduria (D-2-HGA) who accumulated D-2-hydroxyglutarate (D-2-HG) in physiological fluids. Presumed pathogenic mutations were detected in 24 of 50 patients in the D-2-hydroxyglutarate dehydrogenase (D2HGDH) gene, which encodes D-2-hydroxyglutarate dehydrogenase (D-2-HGDH). Enzyme assay of D-2-HGDH confirmed that all patients with mutations had impaired enzyme activity, whereas patients with D-2-HGA whose enzyme activity was normal did not have mutations. Significantly lower D-2-HG concentrations in body fluids were observed in mutation-positive D-2-HGA patients than in mutation-negative patients. These results imply that multiple genetic loci may be associated with hyperexcretion of D-2-HG. Accordingly, we suggest a new classification: D-2-HGA Type I associates with D-2-HGDH deficiency, whereas idiopathic D-2-HGA manifests with normal D-2-HGDH activity and higher D-2-HG levels in body fluids compared with Type I patients. It remains possible that several classifications for idiopathic D-2-HGA patients with diverse genetic loci will be revealed in future studies.

Psychiatric issues in patients with headaches

Comorbidities among headaches and psychiatric disorders have been consistently reported in several clinical studies and reviews. In this paper, we review some recent clinical studies on migraine and tension-type headaches associated with mood, anxiety and somatoform disorders, focusing on therapeutic strategies for the psychiatric disorders.

Nonbacterial osteitis: a clinical, histopathological, and imaging study with a proposal for protocol-based management of patients with this diagnosis

BACKGROUND

Nonbacterial osteitis (NBO), a term referring to sterile bone lesions with nonspecific histopathological features of inflammation, may be either unifocal or multifocal, acute (< or =6 months) or chronic, and recurrent. Only when the condition is chronic, recurrent, and multifocal is it appropriate to use the term chronic recurrent multifocal osteomyelitis (CRMO). We present our clinical experience as the largest reported series of children with NBO to date.

METHODS

We report a retrospective clinical, histopathological, and radiological study of 41 children with nonbacterial osteitis.

RESULTS

Of 41 children (2-16 years of age) diagnosed with NBO in our institution over the last 6 years, 21 (51%) had recurrent disease and 18 (44%) had multifocal disease. The most common bones affected were the clavicle, femur, and tibia (in order of decreasing prevalence) accounting for 44 (63%) of a total of 70 lesions. Only one individual had SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, osteitis) and no other patients had evidence of bowel or skin disease. In the absence of evidence for an infective etiology, we recommend nonsteroidal anti-inflammatory agents as the firstline therapy and bisphosphonates only in cases of resistant disease.

CONCLUSIONS

On the basis of our findings, we propose using a patient questionnaire and protocol for investigating and managing patients who present with NBO to orthopedic surgeons. We predict that this will benefit patients with this disorder by improving our knowledge of the presenting signs and symptoms and related disorders, rationalizing the therapeutic approach, and allowing us to learn about the natural history of the disease.

Detection of beta-catenin mutations in paraffin-embedded sporadic desmoid-type fibromatosis by mutation-specific restriction enzyme digestion (MSRED): an ancillary diagnostic tool

Desmoid-type fibromatosis is a locally aggressive deep soft tissue tumor. Some cases are associated with adenosis polyposis coli germline mutations whereas others harbor somatic beta-catenin point mutations mainly in exon 3, codons 41 and 45. These mutations result in stabilization of beta-catenin, and activation of the Wnt signaling pathway. The aim of this study was to determine the specificity and sensitivity of these 3 most common beta-catenin mutations in the diagnosis of desmoid-type fibromatosis using paraffin-embedded material. The results were compared with nuclear expression of beta-catenin. Mutation-specific restriction enzyme digestion methodology was employed to detect the 3 mutations. One hundred and thirty-three cases were analyzed, including 76 desmoid-type, and 18 superficial fibromatosis, in addition to a further 39 fibromatosis mimics. A restriction site was present for analysis of the codon 41 mutation. Mismatch primers were designed for the codon 45 mutations. Mutations were detected in 66 cases (87%) of 76 desmoid-type fibromatosis (71 extra-abdominal). Of these, 34 (45%) were in codon 45 (TCT>TTT), 27 (35%) in codon 41 (ACC>GCC), and 5 (7%) in codon 45 (TCT>CCT). No mutations were detected in the other lesions studied. All desmoid-type fibromatosis cases and 72% of the mimics tested showed nuclear positivity for beta-catenin indicating immunohistochemistry is a sensitive but not a specific test for desmoid-type fibromatosis. In contrast, to date, beta-catenin mutations have not been detected in any lesions which mimic desmoid-type fibromatosis. Mutation-specific restriction enzyme digestion, a simple and efficient means of detecting the common beta-catenin mutations in desmoid-type fibromatosis, complements light microscopy in reaching a diagnosis.