A novel splicing acceptor variant of the FBN2 gene contributes to a case of congenital contractural arachnodactyly / 中华医学遗传学杂志

OBJECTIVE@#To identify the pathogenic variants from a patient with suspected congenital contractural arachnodactyly, and to explore the possible molecular genetic pathogenesis, so as to provide evidence for clinical diagnosis.@*METHODS@#Whole exome sequencing was performed for the patient. The splicing site variation of candidate pathogenic genes was verified by Sanger sequencing, and the new transcript sequence was determined by RT-PCR and TA-cloning sequencing.@*RESULTS@#The patient carried a heterozygous c.533-1G>C variant of FBN2 gene, which was not reported. The sequencing of mRNA showed that the variant leaded to the disappearance of the canonical splice acceptor site of FBN2 gene and the activation of a cryptic splice acceptor site at c.533-71, resulting in the insertion of 70 bp sequence in the new transcript. It was speculated that the polypeptide encoded by the new transcript changed from valine (Val) to serine (Ser) at amino acid 179, and prematurely terminated after 26 aminoacids. According to the guidelines of American College of Medical Genetics and Genomics, the variant of FBN2 gene c. 533-1G>C was determined as pathogenic (PVS1+PM2+PP3 ).@*CONCLUSION@#A novel splicing variant of FBN2 gene (c.533-1G>C) was identified, which can lead to congenital contractural arachnodactyly.

Analysis of CNTNAP1 gene variants in a Chinese pedigree affected with lethal congenital contracture syndrome type 7 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a couple who had developed polyhydramnios during three pregnancies and given birth to two liveborns featuring limb contracture, dyspnea and neonatal death.@*METHODS@#Whole-exome sequencing (WES) was carried out on fetal tissue and peripheral blood samples from the couple. Suspected variants were verified by Sanger sequencing.@*RESULTS@#The fetus was found to harbor homozygous nonsense c.3718C>T (p.Arg1240Ter) variants of the CNTNAP1 gene, which were respectively inherited from its mother and father. The variant was unreported previously. According to the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be pathogenic (PVS1+PM2+PP4).@*CONCLUSION@#The novel homozygous nonsense variants of the CNTNAP1 gene probably underlay the lethal congenital contracture syndrome type 7 (LCCS7) in this pedigree. Above finding has enabled genetic counseling and prenatal diagnosis for the family.

Miopatías relacionadas a colágeno VI: cuando sospecharlas, cómo identificarlas: aporte de la resonancia magnética muscular / Collagen VI related myopathies: when to suspect, how to identify: the contribution of muscle magnetic resonance

Resumen: Las miopatías secundarias a mutaciones en el colágeno VI (M-COLVI) son las más frecuentes en el hemisferio norte, afectando población adulta y pediátrica. No existen datos de su prevalencia en Latinoamérica. Se caracterizan por presentar una gran variabilidad clínica, desde fenotipos severos, como la distrofia muscular congénita de Ullrich (DMCU), a intermedios y leves como la Miopatía de Bethlem (MB). Su inicio también es variable y se extiende desde el período de recién nacido hasta la vida adulta. Dada la presencia de hiperlaxitud articular, el diagnóstico diferencial se debe realizar con diversas enfermedades del tejido conectivo. El algoritmo diagnóstico clásico en muchos pacientes ha sido insuficiente para orientar el estudio genético de forma adecuada, y a partir de esto la resonancia magnética muscular ha emergido como una herramienta de gran utilidad para una mejor aproxima ción diagnóstica de ésta y otras patologías musculares. Esta revisión tiene como objetivo examinar las formas de presentación, características clínicas, estudio diagnóstico específico, diagnóstico dife rencial y manejo de una de las patologías musculares herediatarias más frecuentes, con énfasis en el aporte de la resonancia magnética muscular.

Abstract: Myopathies secondary to collagen VI mutations (COLVI-M) are the most frequent in the northern hemisphere, affecting the adult and pediatric population. There are no data on its prevalence in Latin America. They are characterized by a great clinical variability, from severe phenotypes, such as Ullrich congenital muscular dystrophy (UCMD), to intermediate and mild ones such as Bethlem myopathy (BM). Its onset is also variable and extends from the neonatal period to adulthood. Given the presence of joint hypermobility, the differential diagnosis should be made with various connective tissue diseases. The classical diagnostic algorithm in many patients has been insufficient to guide the genetic study in an adequate way, and from this the muscular magnetic resonance imaging has emerged as a very useful tool for a better diagnostic approach of this and other muscular pathologies. This ob jective of this review is to study the forms of presentation, clinical characteristics, specific diagnostic study, differential diagnosis and management of one of the most frequent hereditary muscular patho logies, with emphasis on the contribution of muscle magnetic resonance imaging.

The Antley-Bixler syndrome: two new cases.

The Antley-Bixler syndrome is a rare multiple congenital anomaly with a high mortality rate. The characteristic manifestations include craniosynostosis, radiohumeral synostosis, midface hypoplasia, joint contractures and arachnodactyly. We report two new cases of this syndrome and address the diagnostic features, associated malformations, inheritance patterns, prenatal findings, and briefly review the literature.