Medical Genetics for Practicing Obstetrician

Medical genetics has evolved over a decade, and hence, all investigations are available for clinical practice. Many diseases are diagnosed accurately today because of new investigations. These advanced investigations are affordable, accessible and available in day-to-day practice. Hence, there is a need and it is a time for us to understand these advanced technologies. Karyotyping and rapid aneuploidy tests are basic tests, while chromosomal microarray and next-generation sequencing are advanced technologies. It is time to update the knowledge and utilize them in day-to-day practice. These tests are utilized both in prenatal diagnosis and in some clinical scenarios, which are elaborated in detail. Karyotyping is the basic tool to detect both numerical and structural abnormalities. It is advantageous in that it is accurate with error of 0.001% but has a resolution of up to 5 MB. Rapid aneuploidy detection tests are equally accurate and detect as good as 99%. They are FISH, QF-PCR and MLPA. They have high sensitivity and specificity, and results are available within 3 days of time. Hence, these tests are apt for Indian scenarios, where late detection of anomalies (18–20 weeks) is common. Chromosomal microarray is the hybridization technique which detects aneuploidy of all chromosomes. This is useful for detection of deletion and duplication in chromosomes. This is not available for prenatal diagnosis in India now, whereas this is available for prenatal diagnosis in developed countries. Whole-exome sequencing and whole-genome sequencing are advanced techniques which have been described and discussed at length.