Table 1.

Characteristics of complete and partial hydatidiform moles

	Type	Ovum (chr)	Number of sperms (chr)	Mechanism	Ploidy	Karyotype
Complete HM	Androgenetic	Anucleate oocyte	1 (mostly 23X)	Dublication of haploid sperm	Diploid (2 paternal)	46XX
	Androgenetic	Anucleate oocyte	2 (23X + 23Y or 23X + 23X)	Dispermic fertilisation	Diploid (2 paternal)	46XY or 46XX
	Biparental	23X	1 (23X or23Y)	Maternal mutation affecting imprinting in the offspring	Diploid (1 maternal/1 paternal)	46XX or 46XY
Partial HM	Diandric	23X	2 (23X + 23Y or 23X + 23X or (23Y + 23Y	Dispermic fertilisation	Triploid (1 maternal/2 paternal)	69XXY or 69XXX or 69XYY

HM hydatidiform mole, chr chromosome