Infertility & Recurrent Miscarriage

Indications • Genetic Causes

Genetic Causes

Abnormal Chromosome Numbers : Aneuploidy
The most common type of chromosome abnormality is having too many or too few chromosomes. This is called aneuploidy. Aneuploidy is always associated with physical and/or mental developmental problems. The condition at birth is directly related to the type of chromosome abnormality present in the embryo at the time of conception.

Having an extra chromosome is called trisomy and missing a chromosome is monosomy. If the extra or missing chromosome is an autosome (chromosomes 1 to 22), the embryo may not implant or may stop normal development soon after attaching and undergo a spontaneous abortion. If the aneuploidy involves chromosomes 13, 18, 21 X or Y, the embryo may implant and carry to term. Down syndrome (trisomy 21) is the presence of three copies of chromosome 21.



Patau syndrome (trisomy 13) is the presence of three copies of chromosome 13. Edward syndrome (trisomy 18) has three copies of chromosome 18. Other common aneuploidies seen at birth include Klinefelter syndrome and Turner syndrome. Klinefelter syndrome is the presence of an extra sex chromosome (47,XXY), whereas Turner syndrome is missing a sex chromosome (45,X). Embryos affected with Klinefelter syndrome or Turner syndrome may also spontaneously abort.

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