Clinical spectrum of MTOR-related hypomelanosis of Ito with neurodevelopmental abnormalities

PURPOSE: Hypomelanosis of Ito (HI) is a skin marker of somatic mosaicism. Mosaic MTOR pathogenic variants have been reported in HI with brain overgrowth. We sought to delineate further the pigmentary skin phenotype and clinical spectrum of neurodevelopmental manifestations of MTOR-related HI. METHODS: From two cohorts totaling 71 patients with pigmentary mosaicism, we identified 14 patients with Blaschko-linear and one with flag-like pigmentation abnormalities, psychomotor impairment or seizures, and a postzygotic MTOR variant in skin. Patient records, including brain magnetic resonance image (MRI) were reviewed. Immunostaining (n = 3) for melanocyte markers and ultrastructural studies (n = 2) were performed on skin biopsies. RESULTS: MTOR variants were present in skin, but absent from blood in half of cases. In a patient (p.[Glu2419Lys] variant), phosphorylation of p70S6K was constitutively increased. In hypopigmented skin of two patients, we found a decrease in stage 4 melanosomes in melanocytes and keratinocytes. Most patients (80%) had macrocephaly or (hemi)megalencephaly on MRI. CONCLUSION: MTOR-related HI is a recognizable neurocutaneous phenotype of patterned dyspigmentation, epilepsy, intellectual deficiency, and brain overgrowth, and a distinct subtype of hypomelanosis related to somatic mosaicism. Hypopigmentation may be due to a defect in melanogenesis, through mTORC1 activation, similar to hypochromic patches in tuberous sclerosis complex

616 Postzygotic mutations of RHOA cause a mosaic neuroectodermal syndrome

IF 6.287International audienc

Caractérisation clinique et génétique d’une nouvelle dysplasie ectodermique en mosaïque

National audienceIntroduction L’hypomélanose d’Ito est définie par l’association d’une hypopigmentation qui suit les lignes de Blaschko et de manifestations principalement neurologiques. Les autres atteintes associées sont variables. Elle peut être associée à diverses anomalies chromosomiques en mosaïque ou à des mutations MTOR lorsqu’elle s’associe à une hémimégalencéphalie. Nous rapportons un nouveau syndrome clinique avec hypomélanose d’Ito et atteinte neuroectodermique en lien avec des mutations postzygotiques de RHOA . Matériel et méthodes Dans le cadre de la cohorte Mosaic Unknown Skin Traits And Related Disorders (MUSTARD), nous avons étudié 5 patients par séquençage haut débit de l’exome complet ou ciblé, sur peau atteinte et dans le sang. Observations Les 5 patients, non apparentés, présentaient tous une hypopigmentation ou une hypotrichose linéaire, associée à une atteinte faciale bilatérale ou unilatérale (hypoplasie malaire, élargissement de la pyramide nasale), malformations dentaires avec dysplasie de l’émail, doigts et orteils courts, atteinte oculaire avec choroïdose myopique. L’IRM réalisée chez 3 patients a montré une leucoencéphalopathie asymptomatique avec hypersignal de la substance blanche et dilatation des espaces de Virchow. Résultats Chez les deux premiers patients, le séquençage de l’exome en profondeur (144X à 228X) sur peau atteinte a identifié une même mutation en mosaïque p.Glu47Lys du gène RHOA , confirmée par séquençage ciblé (taux allélique : 33,5 % et 23,1 %), absente du sang. Cette mutation a également été identifiée par séquençage ciblé chez deux des autres patients ayant un phénotype similaire. Le cinquième patient était porteur d’une autre mutation postzygotique de RHOA , Pro71Ser, identifiée par séquençage de l’exome. La transfection de plasmides porteurs de ces mutations de RHOA dans des cellules NIH 3T3 en culture a montré une diminution de l’étalement cellulaire, de la formation de fibre de stress, et de la phosphorylation des effecteurs de RhoA , MYPT1 et MLC2, suggérant un effet dominant-négatif de ces mutations. Discussion Nous avons identifié une affection neuroectodermique jamais décrite à notre connaissance, causée par des mutations en mosaïque de RHOA , qui code la protéine RhoA , une petite GTPase de la superfamille Ras, impliquée dans le chimiotactisme, le guidage axonal, et le contrôle du cycle cellulaire. En plus des anomalies fonctionnelles mises en évidence, la forte conservation de la séquence de RHOA au cours de l’évolution est en faveur du caractère pathogène des mutations identifiées. Conclusion Cette dysplasie ectodermique en mosaïque liée à RHOA s’ajoute aux syndromes causés par des mutations létales, pour lesquelles la survie embryonnaire n’est possible que par mosaïcisme. Il s’agit d’une de premières caractérisations moléculaires d’un mosaïcisme pigmentaire, qui souligne l’importance de RHOA dans le développement cutané

Postzygotic inactivating mutations of RHOA cause a mosaic neuroectodermal syndrome

Hypopigmentation along Blaschko’s lines is a hallmark of a poorly defined group of mosaic syndromes whose genetic causes are unknown. Here we show that postzygotic inactivating mutations of RHOA cause a neuroectodermal syndrome combining linear hypopigmentation, alopecia, apparently asymptomatic leukoencephalopathy, and facial, ocular, dental and acral anomalies. Our findings pave the way toward elucidating the etiology of pigmentary mosaicism and highlight the role of RHOA in human development and disease

Hybrid organic-inorganic conductor with a magnetic chain anion: κ-BETS₂[Fe^III(C₂O₄)Cl₂] [BETS = Bis(ethylenedithio)tetraselenafulvalene]

The synthesis, crystal structure, and electrical, optical, and magnetic properties of kappa-BETS2(Fe-III(C2O4)CI2], where BETS is bis(ethylenedithio)tetraselenafulvalene, are reported. The black plate crystals consist of parallel donor layers, two per unit cell, displaying a K-type packing of BETS0.5+ within the bc plane and anionic magnetic chains, [Fe(C2O4)CI2-](n), running along the c axis. It displays metallic behavior clown to 4.2 K, and analysis of the optical reflectivity data gives unscreened plasma energies of 0.69 eV (E parallel to c) and 0.40 eV (E perpendicular to c). The optical anisotropy is larger than that seen for other kappa phases and is described well by transfer integrals obtained from extended Huckel calculations. However, the transfer integrals need to be scaled down uniformly by a factor of 1.21 to reproduce the absolute experimental plasma frequencies. The band structure consists of a one-dimensional (1D) band and a hole pocket, characteristics of kappa phases. The magnetic properties were modeled by the sum of a 1D antiferromagnetic chain contribution from the d spins of Fe3+, a temperature-independent paramagnetic contribution, and a Curie impurity term. At 4.5 K, there is a signature of long-range magnetic ordering to a canted-antiferromagnetic state in the zero-field-cooled-field-cooled magnetizations, and at 2 K, a small hysteresis loop is observed.Chemistry, Inorganic & NuclearSCI(E)18ARTICLE83275-32804

Search for ReCQL4 mutations in 39 patients genotyped for suspected Rothmund-Thomson/Baller-Gerold syndromes

Three overlapping conditions, namely Rothmund-Thomson (RTS), Baller-Gerold (BGS) and RAPADILINO syndromes, have been attributed to RECQL4 mutations. Differential diagnoses depend on the clinical presentation, but the numbers of known genes remain low, leading to the widespread prescription of RECQL4 sequencing. The aim of our study was therefore to determine the best clinical indicators for the presence of RECQL4 mutations in a series of 39 patients referred for RECQL4 molecular analysis and belonging to the RTS (27 cases) and BGS (12 cases) spectrum. One or two deleterious RECQL4 mutations were found in 10/27 patients referred for RTS diagnosis. Clinical and molecular reevaluation led to a different diagnosis in 7/17 negative cases, including Clericuzio-type poikiloderma with neutropenia, hereditary sclerosing poikiloderma, and craniosynostosis/anal anomalies/porokeratosis. No RECQL4 mutations were found in the BGS group without poikiloderma, confirming that RECQL4 sequencing was not indicated in this phenotype. One chromosomal abnormality and one TWIST mutation was found in this cohort. This study highlights the search for differential diagnoses before the prescription of RECQL4 sequencing in this clinically heterogeneous group. The combination of clinically defined subgroups and next-generation sequencing will hopefully bring to light new molecular bases of syndromes with poikiloderma, as well as BGS without poikiloderma

Search for ReCQL4 mutations in 39 patients genotyped for suspected Rothmund-Thomson/Baller-Gerold syndromes.

Three overlapping conditions, namely Rothmund-Thomson (RTS), Baller-Gerold (BGS) and RAPADILINO syndromes, have been attributed to RECQL4 mutations. Differential diagnoses depend on the clinical presentation, but the numbers of known genes remain low, leading to the widespread prescription of RECQL4 sequencing. The aim of our study was therefore to determine the best clinical indicators for the presence of RECQL4 mutations in a series of 39 patients referred for RECQL4 molecular analysis and belonging to the RTS (27 cases) and BGS (12 cases) spectrum. One or two deleterious RECQL4 mutations were found in 10/27 patients referred for RTS diagnosis. Clinical and molecular reevaluation led to a different diagnosis in 7/17 negative cases, including Clericuzio-type poikiloderma with neutropenia, hereditary sclerosing poikiloderma, and craniosynostosis/anal anomalies/porokeratosis. No RECQL4 mutations were found in the BGS group without poikiloderma, confirming that RECQL4 sequencing was not indicated in this phenotype. One chromosomal abnormality and one TWIST mutation was found in this cohort. This study highlights the search for differential diagnoses before the prescription of RECQL4 sequencing in this clinically heterogeneous group. The combination of clinically defined subgroups and next-generation sequencing will hopefully bring to light new molecular bases of syndromes with poikiloderma, as well as BGS without poikiloderma

Investigation of copy number variations on chromosome 21 detected by comparative genomic hybridization (CGH) microarray in patients with congenital anomalies

Abstract Background The clinical features of Down syndrome vary among individuals, with those most common being congenital heart disease, intellectual disability, developmental abnormity and dysmorphic features. Complex combination of Down syndrome phenotype could be produced by partially copy number variations (CNVs) on chromosome 21 as well. By comparing individual with partial CNVs of chromosome 21 with other patients of known CNVs and clinical phenotypes, we hope to provide a better understanding of the genotype-phenotype correlation of chromosome 21. Methods A total of 2768 pediatric patients sample collected at the Genetics Laboratory at Oklahoma University Health Science Center were screened using CGH Microarray for CNVs on chromosome 21. Results We report comprehensive clinical and molecular descriptions of six patients with microduplication and seven patients with microdeletion on the long arm of chromosome 21. Patients with microduplication have varied clinical features including developmental delay, microcephaly, facial dysmorphic features, pulmonary stenosis, autism, preauricular skin tag, eye pterygium, speech delay and pain insensitivity. We found that patients with microdeletion presented with developmental delay, microcephaly, intrauterine fetal demise, epilepsia partialis continua, congenital coronary anomaly and seizures. Conclusion Three patients from our study combine with four patients in public database suggests an association between 21q21.1 microduplication of CXADR gene and patients with developmental delay. One patient with 21q22.13 microdeletion of DYRK1A shows association with microcephaly and scoliosis. Our findings helped pinpoint critical genes in the genotype-phenotype association with a high resolution of 0.1 Mb and expanded the clinical features observed in patients with CNVs on the long arm of chromosome 21