Two new patients with Curry-Jones syndrome with trichoblastoma and medulloblastoma suggest an etiologic role of the sonic hedgehog-patched-GLI pathway

Variants of Uncertain Significance in Vascular Anomalies: The Role of Reclassification

BACKGROUND

Vascular anomalies (VA) are rare developmental disorders due to somatic variants in intracellular growth signaling pathways. Although genetic evaluation is considered the standard of care for optimizing management, the frequency of variants of uncertain significance (VUS) in VA and their clinical implications are not defined.

METHODS

Medical records were reviewed on all patients seen in our VA clinic from January 2014 to August 2024 with vascular malformations or related disorders who had undergone genetic testing. The year and patient age at the time of genetic testing, whether testing was done on peripheral blood or involved tissue, and results were noted. Laboratory vendors were queried about policies for reclassifying VUS and selective re-evaluations of VUS were requested.

RESULTS

In all, 154 patients underwent single gene or gene panel evaluations, with the number of patients tested increasing from zero in 2014 to 39 in 2023; 21 patients had testing done during the first 7 months of 2024. VUS were reported in 22 patients (14%). Many laboratory vendors maintain a policy of revisiting these nonpathogenic variants only when requested by the treating physician. Unsolicited reclassification was reported in a single patient whose VUS was found to be a normal variant. No changes were identified in six other patients whose VUS were re-examined.

CONCLUSIONS

VUS are not uncommon in VA. Reclassification may be possible as more variant-specific data become available and more testing is performed. Centers need to be aware that reclassification efforts are not automatic and should be considered where changes in therapy might result.

Genome-wide association analysis reveals insights into the genetic architecture of mesenteric torsion in pigs

Mesenteric torsion (MT) is a condition that affects several animal species and can lead to the animals' death. However, little is known about its etiology. Therefore, this study aimed to identify genomic regions and candidate genes associated with MT. Phenotypic and genotypic data from 405 pigs, including MT records and genealogy were used. In the model, contemporary group (sex, year, and week of weaning) was considered fixed effect, the linear effect of weaning weight as a covariate, while direct additive genetic effect was random. In the genome-wide association study, genomic windows explaining more than 0.3% of the genetic variance were considered significant. Fifty-two significant windows were identified, covering 299 genes located on 15 chromosomes. The HSD17B4, TNFAIP8, TENM4, CHD2, RGMA, OPRM1, PPARGC1A, CHIA, KCNJ2, KCNJ16, KCNJ15, ELN, SGO1, IL17A, IL17F, GATA4, OVOL2, GLI3, and RAP1A genes were considered candidates to MT since they are related to intestinal morphogenesis, feeding behavior, intestinal barrier, digestion, and intestinal motility. These processes could induce intestinal malformations, dysbiosis, excessive fermentation, delay intestinal transit, and obstruction. Our findings contribute to understanding the mechanisms involved in the occurrence of MT in pigs and may help to elucidate the etiology of intestinal torsion/volvulus in other mammals, including humans.

Medulloblastoma genomics in the modern molecular era

Medulloblastoma (MB) represents a spectrum of biologically and clinically distinct entities. Initially described histopathologically as a small, round blue cell tumor arising in the cerebellum, MB has emerged as a paradigm for molecular classification in cancer. Recent advances in genomic, transcriptomic and epigenomic profiling of MB have further refined molecular classification and complemented conventional histopathological diagnosis. Herein, we review the main clinical and molecular features of the four consensus subgroups of MB (WNT, SHH, Group 3 and Group 4). We also highlight hereditary predisposition syndromes associated with increased risk of MB. Finally, we explore advances in the classification of the consensus molecular groups while also presenting cutting-edge frontiers in identifying intratumoral heterogeneity and cellular origins of MB.

Occurrence and characterization of medulloblastoma in a patient with Curry-Jones syndrome

Medulloblastoma in a Patient with Curry-Jones Syndrome with a mosaic variant, c.1234C > T (p.Leu412Phe), in SMO.

Happle-Tinschert, Curry-Jones and segmental basal cell naevus syndromes, overlapping disorders caused by somatic mutations in hedgehog signalling genes: the mosaic hedgehog spectrum

Happle-Tinschert syndrome (HTS) and Curry-Jones syndrome (CJS; OMIM 601707) are rare, sporadic, multisystem disorders characterized by hypo- and hyperpigmented skin patches following Blaschko's lines, plus acral skeletal and other abnormalities. The blaschkoid pattern implies mosaicism, and indeed CJS was found in 2016 to be caused by a recurrent postzygotic mutation in a gene of the hedgehog signalling pathway, namely SMO, c.1234C>T, p.Leu412Phe. More recently the original case of HTS was found to carry the same somatic mutation. Despite this genetic and phenotypic overlap, two significant differences remained between the two syndromes. The histological hallmark of HTS, basaloid follicular hamartomas, is not a feature of CJS. Meanwhile, the severe gastrointestinal manifestations regularly reported in CJS had not been described in HTS. We report a patient whose phenotype was entirely consistent with HTS apart from intractable constipation, and a second patient with classic features of CJS plus early-onset medulloblastoma, a feature of basal cell naevus syndrome (BCNS). Both had the same recurrent SMO mutation. This prompted a literature review that revealed a case with the same somatic mutation, with basaloid follicular hamartomas and other features of both CJS and BCNS. Segmental BCNS can also be caused by a somatic mutation in PTCH1. We thus demonstrate for the first time phenotypic and genetic overlap between HTS, CJS and segmental BCNS. All of these conditions are caused by somatic mutations in genes of the hedgehog signalling pathway and we therefore propose the unifying term 'mosaic hedgehog spectrum'. What's already known about this topic? Happle-Tinschert syndrome (HTS) and Curry-Jones syndrome (CJS) are rare mosaic multisystem disorders with linear skin lesions. CJS is characterized by severe constipation, which has not previously been reported in HTS. HTS is characterized by basaloid follicular hamartomas, which are not a recognized feature of CJS. The recurrent mosaic SMO mutation found in CJS was recently reported in a patient with HTS. What does this study add? We describe a patient with HTS and intractable constipation, and a case of CJS with medulloblastoma. Both patients had the same recurrent somatic SMO mutation also found in a case reported as segmental basal cell naevus syndrome. SMO functions in the hedgehog pathway, explaining phenotypic overlap between HTS, CJS and mosaic basal cell naevus syndrome. We propose the term 'mosaic hedgehog spectrum' for these overlapping conditions.

Genetics of anophthalmia and microphthalmia. Part 2: Syndromes associated with anophthalmia-microphthalmia

As new genes for A/M are identified in the genomic era, the number of syndromes associated with A/M has greatly expanded. In this review, we provide a brief synopsis of the clinical presentation and molecular genetic etiology of previously characterized pathways involved in A/M, including the Sex-determining region Y-box 2 (SOX2), Orthodenticle Homeobox 2 (OTX2) and Paired box protein-6 (PAX6) genes, and the Stimulated by retinoic acid gene 6 homolog (STRA6), Aldehyde Dehydrogenase 1 Family Member A3 (ALDH1A3), and RA Receptor Beta (RARβ) genes that are involved in retinoic acid synthesis. Less common genetic causes of A/M, including genes involved in BMP signaling [Bone Morphogenetic Protein 4 (BMP4), Bone Morphogenetic Protein 7 (BMP7) and SPARC-related modular calcium-binding protein 1 (SMOC1)], genes involved in the mitochondrial respiratory chain complex [Holocytochrome c-type synthase (HCCS), Cytochrome C Oxidase Subunit 7B (COX7B), and NADH:Ubiquinone Oxidoreductase subunit B11 (NDUFB11)], the BCL-6 corepressor gene (BCOR), Yes-Associated Protein 1 (YAP1) and Transcription Factor AP-2 Alpha (TFAP2α), are more briefly discussed. We also review several recently described genes and pathways associated with A/M, including Smoothened (SMO) that is involved in Sonic hedgehog (SHH) signaling, Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) and Solute carrier family 25 member 24 (SLC25A24), emphasizing phenotype-genotype correlations and shared pathways where relevant.

Gastrointestinal disorders in Curry-Jones syndrome: Clinical and molecular insights from an affected newborn

Curry-Jones syndrome (CJS) is a pattern of malformation that includes craniosynostosis, pre-axial polysyndactyly, agenesis of the corpus callosum, cutaneous and gastrointestinal abnormalities. A recurrent, mosaic mutation of SMO (c.1234 C>T; p.Leu412Phe) causes CJS. This report describes the gastrointestinal and surgical findings in a baby with CJS who presented with abdominal obstruction and reviews the spectrum of gastrointestinal malformations in this rare disorder. A 41-week, 4,165 g, female presented with craniosynostosis, pre-axial polysyndactyly, and cutaneous findings consistent with a clinical diagnosis of CJS. The infant developed abdominal distension beginning on the second day of life. Surgical exploration revealed an intestinal malrotation for which she underwent a Ladd procedure. Multiple small nodules were found on the surface of the small and large bowel in addition to an apparent intestinal duplication that seemed to originate posterior to the pancreas. Histopathology of serosal nodules revealed bundles of smooth muscle with associated ganglion cells. Molecular analysis demonstrated the SMO c.1234 C>T mutation in varying amounts in affected skin (up to 35%) and intestinal hamartoma (26%). Gastrointestinal features including structural malformations, motility disorders, and upper GI bleeding are major causes of morbidity in CJS. Smooth muscle hamartomas are a recognized feature of children with CJS typically presenting with abdominal obstruction requiring surgical intervention. A somatic mutation in SMO likely accounts for the structural malformations and predisposition to form bowel hamartomas and myofibromas. The mutation burden in the involved tissues likely accounts for the variable manifestations.

Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review

Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.

A Recurrent Mosaic Mutation in SMO, Encoding the Hedgehog Signal Transducer Smoothened, Is the Major Cause of Curry-Jones Syndrome

Curry-Jones syndrome (CJS) is a multisystem disorder characterized by patchy skin lesions, polysyndactyly, diverse cerebral malformations, unicoronal craniosynostosis, iris colobomas, microphthalmia, and intestinal malrotation with myofibromas or hamartomas. Cerebellar medulloblastoma has been described in a single affected individual; in another, biopsy of skin lesions showed features of trichoblastoma. The combination of asymmetric clinical features, patchy skin manifestations, and neoplastic association previously led to the suggestion that this could be a mosaic condition, possibly involving hedgehog (Hh) signaling. Here, we show that CJS is caused by recurrent somatic mosaicism for a nonsynonymous variant in SMO (c.1234C>T [p.Leu412Phe]), encoding smoothened (SMO), a G-protein-coupled receptor that transduces Hh signaling. We identified eight mutation-positive individuals (two of whom had not been reported previously) with highly similar phenotypes and demonstrated varying amounts of the mutant allele in different tissues. We present detailed findings from brain MRI in three mutation-positive individuals. Somatic SMO mutations that result in constitutive activation have been described in several tumors, including medulloblastoma, ameloblastoma, and basal cell carcinoma. Strikingly, the most common of these mutations is the identical nonsynonymous variant encoding p.Leu412Phe. Furthermore, this substitution has been shown to activate SMO in the absence of Hh signaling, providing an explanation for tumor development in CJS. This raises therapeutic possibilities for using recently generated Hh-pathway inhibitors. In summary, our work uncovers the major genetic cause of CJS and illustrates strategies for gene discovery in the context of low-level tissue-specific somatic mosaicism.

Sonic Hedgehog, VACTERL, and Fanconi anemia: Pathogenetic connections and therapeutic implications

Three systems with VACTERL association findings- mutations of the Sonic Hedgehog (SHH) signaling pathway in mice, murine adriamycin teratogenicity, and human Fanconi anemia (FA) pathway mutations, may all involve a similar mechanism. SHH is up-regulated in irradiated cells, and DNA breaks common with radiation damage in the adriamycin and FA systems are plausible signals for such effects, which would affect development. Since FA related DNA breakage occurs throughout life, SHH disturbances may account for later FA related findings involving hematopoietic and malignancy issues. In support, androgen, a standard treatment for FA hematologic failure, down-regulates SHH, and common FA malignancies such as squamous cell carcinomas and acute myeloid leukemia have been linked to enhanced SHH function. This suggests that interventions lowering SHH levels may be useful therapeutically. Also supporting a connection between pre- and post- natal findings, the frequency and number of VACTERL anomalies with FA correlate with the severity and onset of hematopoietic and malignancy issues. In FA, radial anomalies are the most common of these defects, followed by renal findings, while vertebral and gastrointestinal anomalies are relatively uncommon, a pattern that differs from observations of the VACTERL association. Genes with more severe effects also show a greatly increased incidence of brain abnormalities, and a paucity of such findings with other FA genes suggests that brain development is relatively refractory to SHH related effects, accounting for the rarity of such findings with the association.