The genomic architecture of the 10q22q23 region is characterised by two low-copy repeats (LCRs3 and 4), and deletions in this region appear to be rare. We report the clinical and molecular characterisation of eight novel deletions and six duplications within the 10q22.3q23.3 region. Five deletions and three duplications occur between LCRs3 and 4, whereas three deletions and three duplications have unique breakpoints. Most of the individuals with the LCR3-4 deletion had developmental delay, mainly affecting speech. In addition, macrocephaly, mild facial dysmorphisms, cerebellar anomalies, cardiac defects and congenital breast aplasia were observed. For congenital breast aplasia, the NRG3 gene, known to be involved in early mammary gland development in mice, is a putative candidate gene. For cardiac defects, BMPR1A and GRID1 are putative candidate genes because of their association with cardiac structure and function. Duplications between LCRs3 and 4 are associated with variable phenotypic penetrance. Probands had speech and/or motor delays and dysmorphisms including a broad forehead, deep-set eyes, upslanting palpebral fissures, a smooth philtrum and a thin upper lip. In conclusion, duplications between LCRs3 and 4 on 10q22.3q23.2 may lead to a distinct facial appearance and delays in speech and motor development. However, the phenotypic spectrum is broad, and duplications have also been found in healthy family members of a proband. Reciprocal deletions lead to speech and language delay, mild facial dysmorphisms and, in some individuals, to cerebellar, breast developmental and cardiac defects.
Background
Aicardi syndrome is a rare X-linked disorder that has been characterized classically by agenesis of the corpus callosum, seizures, and the finding of chorioretinal lacunae. This triad has been augmented more recently by central nervous system and ocular findings. The goal of this study is to determine how frequently other ophthalmologic findings are associated with Aicardi syndrome.
Methods
A single ophthalmologist recorded the ocular and adnexal findings of 40 girls with this disorder at the annual meeting of an Aicardi syndrome family support group. For each subject, the examiner performed facial anthropometrics, portable biomicroscopy, and, where feasible, indirect ophthalmoscopy.
Results
The most common findings were chorioretinal lacunae in 66 (88%) of 75 eyes and optic nerve abnormalities in 61 (81%) of 75 eyes. Other less common findings included persistent pupillary membrane in 4 (5%) of 79 eyes and anterior synechiae in 1 of 79 eyes (1%).
Conclusions
Although the ophthalmic hallmark and defining feature of Aicardi syndrome is the cluster of distinctive chorioretinal lacunae surrounding the optic nerve(s), the spectrum of ocular, papillary, and retinal anomalies varies widely, from nearly normal to dysplasia of the optic nerve and to severe microphthalmos.
Until recently, the prenatal detection of genetic disease was available to only a subset of the pregnant population deemed to be at an increased risk for chromosomal abnormalities or, more rarely, other genetic disorders, based on family history, multiple-marker screening or ultrasound findings. Guided by recent data that indicate that screening for Down syndrome has improved and that risks of invasive procedures are smaller than previously ascertained, the American College of Obstetricians and Gynecologists has recommended that all women have access to invasive prenatal diagnosis. The parallel development of newer genetic diagnostic technologies, such as chromosomal microarray analysis, has made it feasible to simultaneously test for more conditions than was possible with standard karyotype analysis complemented by targeted fluorescence in situ hybridization or mutation detection for specific conditions. In the pediatric and adult population, chromosomal microarray analysis has already been thoroughly evaluated and is now recommended as a first-line diagnostic test for clinically suspected genetic disorders. In this article, we review the current status of array-based comparative genomic hybridization use for prenatal diagnosis and predict that, in the future, it will replace karyotyping as a first-line test for detecting chromosomal abnormalities in the prenatal setting.
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