Chromosomal Disorders

Abstract Chromosomal disorders may be due to abnormalities of chromosome number or structure and may involve autosomes or sex chromosomes. Approximately 7.5% of all conceptions have a chromosomal disorder, but most of these are spontaneously aborted, so the birth frequency is 0.6%. Chromosomal abnormalities generally cause multiple congenital malformations. Children with more than one physical abnormality, particularly if developmentally delayed, should undergo chromosomal analysis as part of their investigation. Recent advances for detecting chromosomal aneuploidies leverage the ability of sensitive DNA sequencing technologies to detect fetal (cell free) DNA circulating in the maternal circulation. Invasive diagnostic testing approaches such as chorionic villus sampling or amniocentesis allow access to tissue or amniocytes that can be tested for fetal chromosomal abnormalities. Many chromosomal disorders have cutaneous manifestations. In this chapter we review the cutaneous manifestations of the commonest chromosomal abnormalities.