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The ClinGen Severe Combined Immunodeficiency Disease Variant Curation Expert Panel: Specifications for classification of variants in ADA, DCLRE1C, IL2RG, IL7R, JAK3, RAG1, and RAG2.

PURPOSE: This collaborative study, led by the Clinical Genome Resource Severe Combined Immunodeficiency Disease Variant Curation Expert Panel (ClinGen SCID-VCEP), implemented and adapted the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines for interpreting germline variants in genes with established relationships to SCID. The effort focused on the 7 most common SCID-related genes identified by SCID newborn screening in North America: ADA, DCLRE1C, IL2RG, IL7R, JAK3, RAG1, and RAG2. METHODS: The SCID-VCEP conducted a rigorous review of variants that involved database analyses, literature review, and expert feedback to derive gene-specific modifications to the ACMG/AMP guidelines. These specifications were validated using a pilot set of 90 variants. RESULTS: Of these 90 variants, 25 were classified as pathogenic, 21 as likely pathogenic, 14 as variants of uncertain significance, 18 as likely benign, and 12 as benign. Seventeen variants with conflicting classifications in ClinVar were successfully resolved. The criteria included modifications to 20 of the 28 original ACMG/AMP criteria specific to SCID-related genes. CONCLUSION: The SCID-specific variant curation guidelines developed by the SCID-VCEP will enhance the precision of SCID genetic diagnosis and provide a robust framework for interpreting variants in SCID-related genes, contributing to appropriate treatment of SCID.

Humans

Dual Aberrant Splicing Caused by an Apparently Missense CHD7 Variant, c.5273A>G (p.Asp1758Gly), in CHARGE Syndrome.

CHARGE syndrome is a rare congenital disorder primarily attributed to heterozygous pathogenic variants of the CHD7 gene. Most pathogenic CHD7 variants are loss-of-function (LoF) variants, whereas the interpretation of missense variants remains challenging in the absence of functional evidence for their pathogenicity. We report a female infant presenting with clinical features characteristic of CHARGE syndrome. Targeted sequencing identified a heterozygous CHD7 variant (NM_017780.4:c.5273A>G), initially annotated as a missense substitution p.Asp1758Gly. This variant has been previously reported and registered with conflicting pathogenicity classifications; however, its transcript-level consequences remain unclear. Long-PCR-based RNA sequencing of total RNA from peripheral blood mononuclear cells revealed two aberrant splicing patterns associated with the variant: a predominant transcript carrying a 28-bp deletion due to cryptic donor splice-site activation, and a minor transcript with partial intron 24 retention. Both transcripts were predicted to result in premature termination codons. These findings demonstrate that c.5273A>G functions as a LoF variant through dual aberrant splicing rather than a simple missense substitution. This case underscores the importance of RNA-level splicing analysis for the accurate interpretation and classification of CHD7 missense variants.

CHD7

Monomorphic adenomas of salivary glands. Trabecular-tubular, canalicular, and basaloid variants.

Eleven cases of monomorphic adenoma of the salivary glands are interpreted as variants of pleomorphic adenomas (mixed tumors) that lack chondroid or myxomatous components. Nine of these tumors were in the parotid gland and two were on the hard palate. Monomorphic adenomas are usually encapsulated and frequently are partially cystic. Their histologic pattern may be confused with that of adenoid cystic carcinoma, but they grow in an expansile fashion and usually are monolobular. Histologically, they may be divided into trabecular-tubular, canalicular, and basaloid variants. Morphologically, they bear a resemblance to basaloid sweat-gland tumors (eccrine spiradenoma and cylindroma).

Adenoma

Integrating AlphaFold2 models and clinical data to improve the assessment of Short Linear Motifs (SLiMs) and their variants' pathogenicity.

Short Linear Motifs (SLiMs) are protein functionally relevant regions that mediate reversible protein-protein interactions. Variants that disrupt SLiMs can lead to numerous Mendelian diseases. Although various bioinformatic tools have been developed to identify SLiMs, most suffer from low specificity. In our previous work, we demonstrated that integrating sequence variant information with structural analysis can enhance the prediction of true functional SLiMs while simultaneously generating tolerance matrices that indicate whether each of the 19 possible single amino acid substitutions (SASs) is tolerated. However, the scarcity of representative crystallographic structures of SLiM-receptor complexes posed a significant limitation. In this study, we demonstrate that these interactions can be modeled using AlphaFold2 (AF2) to generate high-quality structures that serve as input for our MotSASi method. These AF2-derived structures show robust performance, both in reproducing known structures deposited in the Protein Data Bank (PDB) and in reflecting the deleterious effects of known sequence variants. This updated version of MotSASi expands the repertoire of high-confidence predicted SLiMs and provides a comprehensive catalog of variants located within SLiMs, along with their respective deleteriousness assessments. When compared to AlphaMissense, MotSASi demonstrates superior performance in predicting variant deleteriousness. By contributing to the accurate identification and interpretation of variants, this work aligns with ACMG/AMP standards and aims to improve diagnostic rates in clinical genomics.

Humans

Whole-Exome Sequencing in a Consanguinity-Enriched South Indian Retinitis Pigmentosa Cohort: Diagnostic Yield and Molecular Spectrum.

PURPOSE: To determine the molecular diagnostic yield, variant spectrum, inheritance architecture, and influence of consanguinity on whole-exome sequencing outcomes in a South Indian retinitis pigmentosa (RP) cohort. DESIGN: Prospective, registry-based cohort study. SUBJECTS: A total of 113 affected participants were enrolled through the Aravind Registry for Inherited Diseases of the Eye, including 109 unrelated probands and 4 affected relatives from already represented families. Primary analyses were restricted to the 109 unrelated probands. METHODS: Whole-exome sequencing was performed using a clinical exome workflow. Variants were interpreted using American College of Medical Genetics and Genomics/Association for Molecular Pathology criteria and cases were categorized as solved, possibly solved, inconclusive, or unsolved using prespecified inheritance-aware rules. MAIN OUTCOME MEASURES: Molecular diagnostic yield, distribution of implicated genes and variant classes, inheritance architecture, and diagnostic yield stratified by consanguinity status. RESULTS: Among the 109 unrelated probands, mean age at testing was 39.3 ± 14.1 years and 58.7% were male. Whole-exome sequencing identified 186 distinct rare variants across 92 inherited retinal disease genes, including 26 pathogenic and 33 likely pathogenic variants. A molecular diagnosis was established in 50 of 109 probands (45.9%), including 42 solved and 8 possibly solved cases; 45 (41.3%) were inconclusive and 14 (12.8%) remained unsolved, including 4 (3.7%) in whom no candidate variant was identified. EYS, USH2A, and ADGRV1 were the most frequently implicated genes. Autosomal recessive (AR) disease predominated (44/50, 88.0%). Consanguineous AR cases were exclusively homozygous (17/17); notably, 68.0% of nonconsanguineous AR cases were also homozygous (P = 0.013). Diagnostic yield was higher in consanguineous probands (51.4% vs. 41.7%), without reaching significance. Recurrent alleles included an established South Asian founder variant (MFSD8 c.1361T>C) and candidate founder alleles in EYS (c.4321C>T) and ADGRV1 (c.14329C>T). CONCLUSIONS: Whole-exome sequencing established a molecular diagnosis in nearly half of this South Indian RP cohort and revealed a predominantly recessive, homozygosity-enriched architecture shaped by consanguinity. These findings define a region-specific variant landscape to support clinical interpretation, genetic counseling, and future trial enrollment in this underrepresented population. FINANCIAL DISCLOSURES: The authors have no proprietary or commercial interest in any materials discussed in this article.

Consanguinity

Anatomic variants and artifacts in ERCP interpretation.

ERCP is a complex diagnostic procedure requiring manual dexterity, careful attention to endoscopic and radiographic technique, and correct interpretation of the resulting images. Not surprisingly, the procedure is associated with many potential pitfalls. Many of these are related to normal anatomic pancreatic and biliary variants and to artifacts associated with the examination itself. Knowledge of these variants and artifacts is necessary to perform procedures and interpret the results effectively. Our discussion and illustrations are based on a retrospective review of approximately 1300 ERCP studies performed at a single center during a 2-year period.

Biliary Tract

Integrating rare and common variation in epilepsy genetics: from genetic architecture to penetrance and clinical expressivity.

Epilepsy genetics has often been interpreted through a useful but simplified dichotomous framework in which severe epilepsies, particularly developmental and epileptic encephalopathies, are attributed mainly to rare, high-effect variants, whereas more common epilepsies are viewed as arising largely from the cumulative effects of common, small-effect variation. Although this framework has been instrumental for gene discovery, molecular diagnosis, and mechanism-based treatment, it does not fully explain incomplete penetrance, intrafamilial phenotypic heterogeneity, or marked differences in severity among individuals sharing the same molecular diagnosis. Evidence from exome sequencing, copy number variant (CNV) studies, and genome-wide association studies increasingly suggests that rare SNVs/indels, CNVs, and common variant should not be interpreted as entirely independent risk sources, but may partially converge on shared genes, pathways, cell types, and neurobiological processes relevant to neuronal excitability, network stability, and seizure susceptibility. Here, we review evidence across epilepsy subtypes, focusing on convergence and divergence across the allelic spectrum, and discuss how polygenic background and other modifiers may influence penetrance and clinical expressivity among carriers of rare pathogenic variants and CNVs. We also consider implications for variant interpretation, genetic counseling, risk stratification, and precision medicine, while emphasizing that most rare-common integrated models remain insufficiently validated for routine clinical decision-making.

common variants

Eco RI restriction-site polymorphism of the albumin gene in different inbred strains of rat.

Two types of variant EcoRI restriction enzyme patterns of albumin-gene DNA fragments have been detected in different rat strains by agarose gel electrophoresis and Southern blot hybridization using 32P-labeled cloned rat albumin cDNA probes. The type I albumin gene variant is characteristic of the Sprague-Dawley strain, and type II is found in Buffalo rats. The occurrence of these variants is interpreted as the result of simple allelic polymorphism because they are inherited in a normal Mendelian fashion when crossing Sprague-Dawley and Buffalo rats. The distribution of the two genetic variants in various inbred strains of rat suggests that type I represents the original or ancestral form of the albumin gene and that type II appeared spontaneously during laboratory breeding.

Animals

Genomic landscape of hepatocellular carcinoma in Egyptian patients by whole exome sequencing.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Chronic hepatitis and liver cirrhosis lead to accumulation of genetic alterations driving HCC pathogenesis. This study is designed to explore genomic landscape of HCC in Egyptian patients by whole exome sequencing. METHODS: Whole exome sequencing using Ion Torrent was done on 13 HCC patients, who underwent surgical intervention (7 patients underwent living donor liver transplantation (LDLT) and 6 patients had surgical resection}. RESULTS: Mutational signature was mostly S1, S5, S6, and S12 in HCC. Analysis of highly mutated genes in both HCC and Non-HCC revealed the presence of highly mutated genes in HCC (AHNAK2, MUC6, MUC16, TTN, ZNF17, FLG, MUC12, OBSCN, PDE4DIP, MUC5b, and HYDIN). Among the 26 significantly mutated HCC genes-identified across 10 genome sequencing studies-in addition to TCGA, APOB and RP1L1 showed the highest number of mutations in both HCC and Non-HCC tissues. Tier 1, Tier 2 variants in TCGA SMGs in HCC and Non-HCC (TP53, PIK3CA, CDKN2A, and BAP1). Cancer Genome Landscape analysis revealed Tier 1 and Tier 2 variants in HCC (MSH2) and in Non-HCC (KMT2D and ATM). For KEGG analysis, the significantly annotated clusters in HCC were Notch signaling, Wnt signaling, PI3K-AKT pathway, Hippo signaling, Apelin signaling, Hedgehog (Hh) signaling, and MAPK signaling, in addition to ECM-receptor interaction, focal adhesion, and calcium signaling. Tier 1 and Tier 2 variants KIT, KMT2D, NOTCH1, KMT2C, PIK3CA, KIT, SMARCA4, ATM, PTEN, MSH2, and PTCH1 were low frequency variants in both HCC and Non-HCC. CONCLUSION: Our results are in accordance with previous studies in HCC regarding highly mutated genes, TCGA and specifically enriched pathways in HCC. Analysis for clinical interpretation of variants revealed the presence of Tier 1 and Tier 2 variants that represent potential clinically actionable targets. The use of sequencing techniques to detect structural variants and novel techniques as single cell sequencing together with multiomics transcriptomics, metagenomics will integrate the molecular pathogenesis of HCC in Egyptian patients.

Humans

Whole exome sequencing of paediatric patients with Cogan's syndrome to identify monogenic mimics.

OBJECTIVES: Cogan's syndrome (CS) is a rare variable vessel vasculitis, describing sensorineural hearing loss (SNHL), inflammatory ocular disease and vestibular dysfunction. We hypothesized that within paediatric-onset (p)CS, a proportion would have monogenic disease, either autoinflammatory and/or associated with SNHL. METHODS: Whole exome sequencing (WES) was performed and analysed using an in-house pipeline incorporating virtual gene panels for inflammation and SNHL; copy number variant analysis (ExomeDepth); and phenotype-driven variant prioritization (Exomiser). Genetic variants were interpreted by a multi-disciplinary team according to American College of Medical Genetics and Genomics guidelines. RESULTS: Ten patients with a clinical diagnosis of pCS were enrolled. Three/10 (30%) had a monogenic contribution to the phenotype based on Class 4/5 variants: de novo NLRP3 p.T915R (n = 1) associated with Cryopyrin-associated periodic syndrome; MYO7A p.K542Qfs*5 (n = 1) causing SNHL; and HBB homozygous p.E7V causing sickle cell disease (associated with hearing loss and uveitis). A further two cases had possible monogenic contribution with the following rare variants of uncertain significance (class 3): ADGRV1 compound heterozygous variants (n = 1) associated with Usher syndrome; and a novel ALPK1 p.H735P (n = 1), associated with Retinal dystrophy Optic nerve oedema Splenomegaly Anhidrosis Headache (ROSAH) syndrome. CONCLUSIONS: In children presenting with features suggesting CS, genetic screening should be considered before conferring this rare diagnostic label since at least 30% had an alternative monogenic contribution to the phenotype rather than true pCS, with implications for treatment and prognosis. We thus advocate for genetic testing using next-generation sequencing for patients presenting with pCS.

Humans

Whole-exome sequencing-centered genetic evaluation for early-onset obesity in Chinese children: a retrospective single-center cohort.

BACKGROUND: Genetic causes of early-onset obesity remain undercharacterized in East Asian children. This study evaluated a whole-exome sequencing (WES)-centered diagnostic workflow in Chinese children with obesity onset before 5 years. METHODS: Consecutive children with body mass index above the 95th percentile and obesity onset before 5 years who completed structured inpatient assessment at a single center between February 2022 and December 2023 were retrospectively analyzed. Phenotyping included clinical, biochemical, oral glucose tolerance, cortisol rhythm, and liver assessments. Genetic testing combined WES, mitochondrial DNA analysis, multiplex ligation-dependent probe amplification (MLPA) for obesity-related imprinting loci, WES-based copy-number variant and runs-of-homozygosity analyses, and Sanger validation. Variants were interpreted according to the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria. RESULTS: Among 23 children, clinically relevant genetic findings were identified in 6 (26.1%): melanocortin-4 receptor (MC4R) c.831T>A (p.C277*), maternal uniparental disomy of 15q11-13, and four phenotype-correlated variants of uncertain significance in UCP3, BBS1, NCOA1, and SH2B1. The definitive/likely diagnostic yield, restricted to pathogenic or confirmed imprinting findings, was 8.7% (2/23). Findings involved leptin-MC4R signaling, BBSome function, fatty-acid oxidation, and chromosomal imprinting. Genetically positive children showed numerically higher alanine aminotransferase (ALT) and aspartate aminotransferase (AST), but differences were not statistically significant. BBS1 p.T374S was relatively enriched in East Asian reference data. CONCLUSIONS: A WES-centered integrated workflow detected heterogeneous genetic mechanisms in Chinese children with early-onset obesity, but variant of uncertain significance (VUS)-associated findings should be distinguished from confirmed diagnoses. Orthogonal methylation/MLPA and runs of homozygosity (ROH) analyses were necessary for imprinting diagnosis. Larger multicenter studies and functional validation are needed.

Chinese children

Real-world clinical utility of exome sequencing in pediatric drug-resistant epilepsy: Experience from a tertiary center in Thailand.

BACKGROUND: Genomic testing has increasingly contributed to the diagnosis and management of pediatric drug-resistant epilepsy (DRE), particularly in patients with suspected genetic etiologies. This study evaluated the diagnostic yield and real- world clinical utility of whole-exome sequencing (WES) in children with DRE. METHODS: Children with DRE and seizure onset before 15 years of age were enrolled between January 2020 and December 2023. Clinical data, including demographics, seizure characteristics, developmental history, electroencephalography (EEG), brain magnetic resonance imaging (MRI), and prior investigations, were reviewed. WES was performed in all probands and, when available, their parents. Variants were interpreted according to standard guidelines. Clinical utility and 1-year seizure and developmental outcomes were assessed from follow-up records. RESULTS: Fifty-six patients (23 males, 33 females) were included. The median age at seizure onset was 1 year (interquartile range [IQR] 0.3-4 years), and 96.4% had developmental comorbidities. Pathogenic or likely pathogenic variants were identified in 39% (22/56), with the highest diagnostic yield in children with seizure onset before 3 years of age. Channelopathies accounted for most genetically solved cases (68%), predominantly involving sodium channel genes. Genetic diagnoses provided clinical utility in 73% (16/22) of solved cases by guiding treatment and precision management. At 1-year follow-up, genetically solved patients showed more favorable seizure and developmental outcomes than those with genetically unsolved patients. CONCLUSION: WES achieved a 39% diagnostic yield and substantial clinical utility in pediatric DRE, particularly in early-onset and channelopathy-related disorders. These findings support early molecular diagnosis to facilitate genotype-informed management in appropriately selected children. However, the more favorable developmental and seizure outcomes observed in genetically solved patients should be interpreted with caution, as they may have been influenced by multiple factors beyond genetic diagnosis. In resource-limited settings, careful clinical phenotyping remains essential for treatment decisions and for prioritizing children for genomic testing.

Clinical utility

Integrating Next-Generation Sequencing into von Willebrand Disease Diagnostics: Insights from the PCM-EVW-ES Multicenter Project.

Von Willebrand disease (VWD) is the most common inherited bleeding disorder, caused by quantitative or qualitative defects in von Willebrand factor (VWF). Diagnosis is challenging and requires integrating bleeding history, VWF antigen and activity measurements, FVIII assays, and specialized phenotyping. Genetic testing is increasingly recognized as a key component. Here, we review current concepts in VWD diagnostics and highlight the Spanish Clinical and Molecular Profile of von Willebrand Disease (PCM-EVW-ES) project as a model for genomics-enabled precision medicine. PCM-EVW-ES is a multicenter initiative involving 48 hospitals, centralized phenotypic testing, and next-generation sequencing of the VWF coding region, enabling definitive classification in 730 individuals with VWD to date. Harmonized recruitment criteria and standardized workflows improve subtype assignment, uncover complex genotypes, refine genotype-phenotype correlations, and facilitate the identification of asymptomatic carriers. The PCM-EVW-ES variant spectrum highlights recurrent disease-causing variants in Spain and underscores the value of coordinated national registries for variant curation. Building on these data, we propose a diagnostic algorithm in which bleeding assessment and first-line VWF/FVIII assays, combined with, early VWF molecular testing increases diagnostic accuracy and guides targeted second-line investigations to confirm and refine VWD subtype classification. We also outline persisting challenges, including the interpretation of variants of uncertain significance and patients without identifiable pathogenic VWF variants, and future directions integrating third-generation sequencing, expanded gene panels, functional studies, and artificial-intelligence-driven multiomic approaches. Together, these advances illustrate how robust multicenter studies can bridge the gap between complex diagnostics and clinical practice in VWD.

Humans

Whole exome sequencing identifies three novel variants and establishes the molecular diagnosis of ATP6V0A4-related distal renal tubular acidosis in a lebanese infant.

BACKGROUND: Distal renal tubular acidosis (dRTA) is a rare inherited disorder characterized by impaired urinary acidification, leading to metabolic acidosis, hypokalemia, nephrocalcinosis, and growth impairment. Pathogenic variants in ATP6V0A4 are among the most common genetic causes of autosomal recessive dRTA. METHODS AND RESULTS: We report a Lebanese infant presenting with failure to thrive, recurrent vomiting, severe hyperchloremic metabolic acidosis, hypokalemia, and bilateral nephrocalcinosis, in whom whole-exome sequencing (WES) was performed to establish the molecular diagnosis and perform a comprehensive genomic evaluation. WES identified three novel variants, including a novel homozygous likely pathogenic ATP6V0A4 variant, consistent with the patient's phenotype. Two additional novel variants in TTN and CEP290 were also detected. Family segregation analysis confirmed the inheritance pattern of all three variants and refined the interpretation of the additional genomic findings. The patient showed sustained clinical and biochemical improvement to alkali therapy, with normalization of biochemical abnormalities and improvement in growth during follow-up. CONCLUSIONS: This report expands the molecular spectrum of ATP6V0A4-related dRTA and illustrates the clinical utility of comprehensive WES combined with segregation analysis for accurate molecular diagnosis, variant interpretation, genetic counseling, and the evaluation of additional genomic findings in rare inherited disorders.

Humans

Relative accuracy of three automated systems for neuropsychological interpretation.

Three computer programs for automated interpretation of variants of the Halstead-Reitan Neuropsychological Test Battery were tested on cases in two data sets. The Key approach of Russell, Neuringer, and Goldstein (1970), Brain I (Finkelstein, 1977), and Adams' (1975) ability-based algorithm were employed in the study. The first data set included 63 well-documented cases with precise criterion data and multiple sources of direct verification. The second data set consisted of 30 equally well-studied cerebrovascular disease patients whose cerebral circulation disorders resulted in clinical manifestations encompassing the entire range of stroke. Results suggested that, while none of the programs do poorly at identifying the presence of brain damage, lateralization and possibly other localization/process predictions are not done well by these programs. The failure described in this particular study does not imply that automated methods are potentially less effective than true actuarial or clinical ones. Rather, we suggest that the translation process from clinical interpretation to the mechanical combinatory logic of the digital computer is at an early stage.

Aged

The Animal Variant Classification Guidelines v2: An Update With New Criteria and Improved Clarifications.

The Animal Variant Classification Guidelines (AVCG) were developed to standardize and objectify the classification of putative disease-causing variants. These guidelines are sufficiently reproducible and are used to classify previously published and new disease-causing variants across species. Here, the guidelines are updated (AVCG.v2), based on a three-phase decision process. Overall, four new criteria and seven clarifying comments were added. The number of criteria has increased from 23 to 27, with three new criteria supporting pathogenicity and one new criterion supporting benign classification. Pharmacogenomic variants were determined to fall within the scope of the guidelines. These updated guidelines are being used by the Variant Pathogenicity Working Group (VPWG), part of the Animal Genetic Testing Standardization standing committee, which is a committee of elected members of the International Society for Animal Genetics (ISAG). Under the auspices of ISAG, the VPWG retrospectively classifies published putative disease-causing variants. The pathogenicity label for a variant will be presented in the variant tables of Online Mendelian Inheritance in Animals (OMIA; https://omia.org/). The AVCGv.2 criteria and recommendations were developed by the expertise of the animal genetics community and the ISAG Executive Committee through the Animal Genetics Testing Standardization Committee endorses and strongly encourages their use to evaluate the evidence supporting pathogenicity of putative disease-causing variants.

Animals

Guidelines for Genetic Testing of Peripheral Nerve Disorders.

Inherited peripheral neuropathies (IPNs) comprise a clinically and genetically heterogeneous group of disorders affecting approximately 1 in 2500 individuals and represent one of the most common inherited neurologic diseases. The rapidly expanding identification of disease-causing genes and the widespread implementation of next-generation sequencing (NGS) have fundamentally transformed the diagnostic evaluation of these disorders. Contemporary molecular testing has substantially increased diagnostic yield, shortened the diagnostic delay, refined disease classification, and strengthened genotype-phenotype correlations. In the United States, NGS-based multigene panels have become the most cost-effective first-line molecular diagnostic approach for most patients with suspected inherited neuropathies, whereas phenotype-directed single-gene testing remains appropriate in selected clinical circumstances and in healthcare systems in which access to comprehensive sequencing is limited. Despite these advances, challenges continue to affect diagnostic accuracy, including interpretation of variants of uncertain significance, detection of copy number variants and repeat expansions, technical limitations associated with highly homologous genomic regions such as SORD, and variability in gene content and analytic performance among commercially available testing platforms. Accurate diagnosis therefore requires integration of clinical phenotype, electrodiagnostic findings, family history, and molecular data. Establishing a precise genetic diagnosis has become increasingly important because it improves prognostic accuracy, guides genetic counseling and cascade testing, identifies patients with treatable hereditary neuropathies such as transthyretin amyloidosis, and facilitates enrollment in gene-specific clinical trials and emerging precision therapies. An evidence-based, phenotype-driven approach that incorporates contemporary molecular technologies is essential to maximize diagnostic efficiency while recognizing the strengths and limitations of currently available genetic testing strategies.

Charcot–Marie–tooth disease

Palmar fibromatosis (Dupuytren's contracture). Ultrastructural and enzyme histochemical studies of 43 cases.

Forty three cases of palmar fibromatosis were studied by light and electron microscopy, enzyme histochemistry, and ultrastructural immunohistochemistry. By electron microscopy most of the cells composing the nodules in both the proliferative and the involutional stages were identical to myofibroblasts. The myofibroblasts in the involutional nodules often possessed microfilament aggregates probably representing contraction of micro(actin)filaments in the cytoplasm. The proliferative nodules revealed small perivascular haemorrhages and haemosiderin deposits accompanied by accumulation of macrophages and some lymphocytes; these inflammatory cells possibly secrete a certain growth factor inducing proliferation of genetically abnormal fibroblasts and myofibroblasts. Diaminopeptidase IV was detected in myofibroblasts and fibroblasts by enzyme histochemistry and ultrastructural immunohistochemistry; the enzyme may play a role in the metabolism of intercellular substances. Some perivascular mesenchymal cells, interpreted as variants of myofibroblasts, had moderate activity of alkaline phosphatase.

Acid Phosphatase