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Otocephaly is a severe and lethal malformation. We report a new case of a fetus with Agnathia-Otocephaly, presenting only the facial findings but with otherwise normal organs. The fetal karyotype was normal. We examined the fetal DNA for uniparental disomy of chromo-somes 3 and 4, since the mother is a carrier of a t(3;4) chromosome, but did not identify any evidence. We were also unable to find mutations or possible associations with candidate Otocephalic genes, including OTX2 and PGAP1. These findings suggest that the molecular etiology of Agnathia-Otocephaly is still unknown with a mutation yet to be identified in humans. [ABSTRACT FROM AUTHOR]

Current models on the etiology of psychiatric disorders support the idea of a biologic cause as well as interactions of biologic systems with the environment. The elucidation of the genetic etiology is of paramount importance to understand the cause of psychiatric disorders. Human chromosome 18 was identified as one of the first chromosomes to be aberrant in psychiatric patients and has subsequently served as a model to identify the molecular cause. In this article I review a multitude of methodologies that can be used in determining the genetic basis of schizophrenia, affective disorder and autism associated with human chromosome 18. These strategies include the use of chromosome aberrations, linkage and association studies, mouse-human comparative genomics, mutation analysis on candidate genes, trinucleotide repeat expansion studies, search for genes demonstrating parental effects and bioinformatics. Current data from the use of these methods are cited from the literature. Linkage and association studies have suggested at least 2 candidate loci on the short and long arms of chromosome 18 for each of these psychiatric disorders. Some loci are supported by the mapping of chromosome aberrations from psychiatric patients. Mutation analyses of psychiatric patients with 4 candidate genes (NEDD4L, IMPA2, PACAP and GNAL) mapping within these loci have been unsuccessful, although an association was found with the IMPA2 gene in patients with schizophrenia. With these methods and findings, our understanding of the cause of psychiatric disorders associated with human chromosome 18 has improved and will advance, especially with emerging data from the human and rodent genome projects. [ABSTRACT FROM AUTHOR]

We report a new and rare case of recurrent anencephaly in a family with no other apparent abnormalities. The karyotypes of the family and all affected subjects were normal. Thorough mutational analyses of VANGL1 of chromosome 1p13.1 and FOXN1 of chromosome 17q11-q12, genes that are associated with phenotypes of the anencephaly spectrum, unfortunately did not disclose any DNA variations in an affected fetus of this family. The etiology of recurrent anencephaly in this family is therefore due to mutations in genes yet to be discovered, perhaps of the planar cell polarity pathway, or to possible environmental gestational factors during development. [ABSTRACT FROM AUTHOR]

Abstract: Agnathia-otocephaly, a rare, sporadic and lethal malformation, is characterized by microstomia (small mouth), aglossia (absence of the tongue), agnathia (absence of the lower jaw) and abnormally positioned ears. It is a principal anomaly derived from the first pharyngeal arch as a consequence of failed mesenchymal migration of the maxillary prominence and atrophy in the development of the mandibular prominences. Unfortunately, these patients have poor prognoses and may succumb to death shortly after birth due to respiratory problems if appropriate airway management is not implemented. Difficulties persist in the prenatal diagnosis of agnathia-otocephalic patients. However, two- and three-dimensional ultrasonography, computed tomography and magnetic resonance imaging technologies now offer significant improvements in refining the resolution of distinctive facial anomalies. This complex disorder can be attributed to both genetic and teratogenic causes, in addition to other unidentifiable factors. Furthermore, studies in model organisms, in particular mice, have unraveled potential genetic pathways that may contribute to the etiology. This article highlights current perspectives on agnathia-otocephaly with a focus on the etiological causes and issues concerning prenatal diagnosis, differential diagnosis, prognosis and genetic counseling. Finally, studies using animal models especially genetically engineered mice are described to comprehend the molecular genetic interactions that may occur during the genesis of this intriguing craniofacial birth defect. [ABSTRACT FROM AUTHOR]