19 12 Prenatal Diagnosis of Sex Chromosome Abnormalities Incidence Ascertainment bias Patterns of inheritance Prenatal diagnosis Turner syndrome Klinefelter syndrome Triple X and poly‐X syndromes 47,XYY males Polysomy Y karyotypes Structural abnormalities of the X chromosome Structural abnormalities of the Y chromosome Disorders of sex development Conclusion References
20 13 Prenatal Diagnosis of Chromosomal Abnormalities: From Karyotype to Microarray The study and impact of chromosome abnormalities in humans Traditional cytogenetic testing: analysis of the G‐banded metaphase Incidence and spectrum of chromosome abnormalities observed in prenatal diagnosis Rapid identification of the common aneuploidies Chromosome microarray analysis adds diagnostic yield over karyotyping and rapid aneuploidy techniques Types of microarrays Microarray design for clinical testing Interpreting and reporting of CMA results Factors affecting CMA diagnostic yield CMA in routine pregnancies CMA in pregnancies with ultrasound anomalies CMA versus karyotyping: additional points to consider CMA and genetic counseling Conclusion References
21 14 Molecular Genetics and Prenatal Diagnosis Diagnostic methods: use, limitations, and pitfalls Clinical caveats, cautions, limitations, and pitfalls Prenatal diagnosis of mitochondrial disorders Reporting incidental (secondary) results Ethical considerations in prenatal testing References
22 15 Prenatal Diagnosis of Cystic Fibrosis Genetics and epidemiology Clinical features Diagnosis Treatment Discovery of the cystic fibrosis gene Genotype–phenotype correlation Congenital bilateral absence of the vas deferens Modifier genes Ethnic variation in mutation frequencies Development and implementation of public policy for CF population carrier screening and the core mutation panel Laboratory methods Expanded panels Outcomes of the CF carrier screening program Special prenatal diagnosis situations Future directions References
23 16 Prenatal Diagnosis and the Spectrum of Involvement from Fragile X Mutations Introduction Epidemiology Clinical involvement in those with the full mutation Clinical phenotype in the premutation Pathogenesis of the premutation‐associated disorder FXTAS Molecular prenatal diagnosis methodology Preimplantation genetic testing and polar body analysis Neurobiologic advances and targeted treatment in the full mutation Genetic counseling Acknowledgments References
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17 Prenatal Diagnosis of Fetal Malformations by Ultrasound
Introduction
Craniospinal defects
Fetal face