Commentary on: Expression of cystathionine beta-synthase and histopathological observations in placentas of patients with Down syndrome

Down syndrome, which occurs in about1 in 1,000 births, is the most common genetic cause of mental retardation and the most common aneuploidy in live births. Historical records show that the condition has been recognized for thousands of years [1, 2]. The first depictions in the medical literature were made in the first half of the nineteenth century, with John Langdon Down’s description following approximately twenty years later [2, 3]. Trisomy 21 was shown to be the cause of Down syndrome over half of a century ago [4]; the chromosomal causes of the other common aneuploidy-related syndromes, such as Turner syndrome (monosomy X), Patau syndrome (trisomy 13), and Edwards syndrome (trisomy 18) were all described within the same several year period [5–7].

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Corresponding author: Benjamin D. Solomon, MD, Division of Medical Genomics, Inova Translational Medicine Institute, Associate Professor, Virginia Commonwealth University School of Medicine, 3300 Gallows Road, Claude Moore Building, 2nd Floor, Falls Church, VA 22042, USA. Tel.: +1 703 776 6118; Fax: +1 703 776 7177; E-mail: