The term 'Genetic Syndrome' though often used loosely, indicates co occurrence of distinct abnormalities, which are presumably caused by a single genetic defect. There are thousands of genetic syndromes reported in literature, and many more are yet to be reported. Memorizing the clinical pictures of various syndromes is neither possible nor advisable. Hence, presence of multiple malformations in a case is a diagnostic challenge. Thus, systematic clinical approach is essential for syndrome identification. Role of genetics is mainly preventive in medical practice. Hence for the computation of risk and reliable preventive procedures accurate diagnosis in the affected individual or family is a necessity.
There are different types of genetic syndromes. Those caused by chromosomal abnormalities account for approximately 5% of all the congenital malformations. Usually, there are two or more malformations associated in chromosomal disorders. Many of the chromosomal syndromes are not compatible with life. They end up as spontaneous abortion or late fetal death. Any recognizable defect of any autosome is usually associated with several structural and developmental defects. Nearly, 1 in every 100 newborns have some or the other chromosomal abnormality. Chromosomal syndromes frequently seen in liveborns are Down's syndrome, Turner's syndrome, Klinefelter's syndrome, Patau syndrome, Edward's syndrome, Cri-du-chat syndrome, Fragile-X syndrome etc.
Genetic syndromes caused by single gene defects account for approximately, 7.5% of all congenital malformations. Single gene defects may present either as isolated defect or multiple malformation syndromes. Few examples of multiple malformation syndromes caused due to single gene defects are Holt-Oram syndrome, Nail-patella syndrome, Robert syndrome, Smith-Lemli-Opitz syndrome, Zellweger syndrome etc.
In multifactorial syndromes, both genes and the environmental factors play 3 role in causation of the disease.
It is not always possible to arrive at the accurate genetic diagnosis. There are number of reasons for this. But, suspecting a genetic syndrome and following a systematic approach leading to final diagnosis is necessary for genetic counseling and further management.
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