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Molecular Genetics & Genomic Medicine Apr 2020Agnathia-otocephaly is a rare and lethal anomaly affecting craniofacial structures derived from the first pharyngeal arch. It is characterized by agnathia, microstomia,...
BACKGROUND
Agnathia-otocephaly is a rare and lethal anomaly affecting craniofacial structures derived from the first pharyngeal arch. It is characterized by agnathia, microstomia, aglossia, and abnormally positioned auricles with or without associated anomalies. Variants affecting function of OTX2 and PRRX1, which together regulate the neural crest cells and the patterning of the first pharyngeal arch as well as skeletal and limb development, were identified to be causal for the anomaly in a few patients.
METHODS
Family-based exome sequencing (ES) on a fetus with severe agnathia-otocephaly, cheilognathopalatoschisis, laryngeal hypoplasia, fused lung lobes and other organ abnormalities and mRNA expression analysis were performed.
RESULTS
Exome sequencing detected a de novo SMAD3 missense variant in exon 6 (c.860G>A) associated with decreased mRNA expression. Variants in SMAD3 cause Loeys-Dietz syndrome 3 presenting with craniofacial anomalies such as mandibular hypoplasia, micro- or retro-gnathia, bifid uvula and cleft palate as well as skeletal anomalies and arterial tortuosity. The SMAD3 protein acts as a transcriptional regulator in the transforming growth factor β (TGFB) and bone morphogenetic (BMP) signaling pathways, which play a key role in the development of craniofacial structures originating from the pharyngeal arches.
CONCLUSION
Agnathia-otocephaly with or without associated anomalies may represent the severe end of a phenotypic spectrum related to variants in genes in the interacting SMAD/TGFB/BMP/SHH/FGF developmental pathways.
Topics: Craniofacial Abnormalities; Fetus; Genetic Testing; Humans; Loss of Function Mutation; Phenotype; Smad3 Protein; Ultrasonography, Prenatal; Exome Sequencing
PubMed: 32100971
DOI: 10.1002/mgg3.1178 -
European Journal of Human Genetics :... Jul 2012Array-based genome-wide segmental aneuploidy screening detects both de novo and inherited copy number variations (CNVs). In sporadic patients de novo CNVs are...
Array-based genome-wide segmental aneuploidy screening detects both de novo and inherited copy number variations (CNVs). In sporadic patients de novo CNVs are interpreted as potentially pathogenic. However, a deletion, transmitted from a healthy parent, may be pathogenic if it overlaps with a mutated second allele inherited from the other healthy parent. To detect such events, we performed multiplex enrichment and next-generation sequencing of the entire coding sequence of all genes within unique hemizygous deletion regions in 20 patients (1.53 Mb capture footprint). Out of the detected 703 non-synonymous single-nucleotide variants (SNVs), 8 represented variants being unmasked by a hemizygous deletion. Although evaluation of inheritance patterns, Grantham matrix scores, evolutionary conservation and bioinformatic predictions did not consistently indicate pathogenicity of these variants, no definitive conclusions can be drawn without functional validation. However, in one patient with severe mental retardation, lack of speech, microcephaly, cheilognathopalatoschisis and bilateral hearing loss, we discovered a second smaller deletion, inherited from the other healthy parent, resulting in loss of both alleles of the highly conserved heat shock factor binding protein 1 (HSBP1) gene. Conceivably, inherited deletions may unmask rare pathogenic variants that may exert a phenotypic impact through a recessive mode of gene action.
Topics: Alleles; Computational Biology; DNA Copy Number Variations; DNA Mutational Analysis; Gene Deletion; Gene Dosage; Gene Library; Genes, Recessive; Genetic Testing; Genome, Human; Heat-Shock Proteins; Hemizygote; Humans; Inheritance Patterns; Intellectual Disability; Phenotype; Sensitivity and Specificity
PubMed: 22258528
DOI: 10.1038/ejhg.2011.263 -
Interdisciplinary Toxicology Dec 2017Despite modern approaches in molecular biology and genetics, we are still not able to identify the actual cause in more than 50% of all congenital defects. One-half of...
Despite modern approaches in molecular biology and genetics, we are still not able to identify the actual cause in more than 50% of all congenital defects. One-half of the unidentified cases is referred to as "multifactorial". Detailed prenatal investigation of the fetus can discover the presence of congenital abnormality, which can worsen the process of postnatal adaptation. Retrospective analysis of newborns admitted to the Neonatal Department of Intensive Medicine (NDIM) in 2012-2016 with the aim to analyze how the process of postnatal adaptation can be changed by the presence of congenital abnormalities of lip and palate. During a five-year period, 13 newborns were admitted to NDIM (2 premature; 11 term newborns). Chromosomal abnormality was confirmed in one patient (Down syndrome) and in one patient suspicion of Patau syndrome was found. Twelve newborns had complete cheilognathopalatoschisis. Two premature newborns and two term newborns had perinatal asphyxia. In this group of patients, 33% had respiratory insufficiency without the presence of congenital heart abnormality, 66% had congenital heart abnormality with respiratory insufficiency, and 2 patients had feeding problems. Only one patient had a positive family history. The diagnosis of complete cheilognathopalatoschisis was confirmed prenatally only in 9 patients. We confirmed that clinical consequences of congenital abnormalities of lip and palate depend on the nature, localization and range of abnormalities, as well as on the genetic background and accompanying congenital abnormalities. Prenatal confirmation of the presence of congenital abnormalities has an important influence on the postnatal management of a patient.
PubMed: 30147425
DOI: 10.1515/intox-2017-0024