Are there earlier onset or later onsets of Trisomy 13?
The extra copy of chromosome 13 is present in the baby's cells from early in prenatal development. Some symptoms of trisomy 13 are revealed through prenatal ultrasounds or prenatal testing. Babies with complete trisomy 13 will almost always have symptoms before birth, such as growth being slower than expected while in the womb. There is no "late onset" form of Trisomy 13.
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