Genetics of hht.



Hht is a genetic condition, it is inherited in an autosomal dominant manner. This means it is passed on from one parent to their child. For someone with hht they carry one abnormal gene with a 50% chance of passing that gene onto each child. Hht can not skip a generation then reappear, but sometime a person can be so mildly affected they are unaware they have hht.


There are at least five recognized genetic types of hht, three of these have been associated with particular genes while two currently are not associated to a partcular gene. There are over 600 mutations known to cause hht.


Apart from  SMAD4 mutations which causes also juvenile polyposis as well as hht, it is unclear as to if the gentic mutation is more likely to cause specific difficulties. 


HHT1  or genetic type ENG 

HHT2 or genetic type ACVRL1

HHT3 or non specific gene

HHT4 or non specific gene

JPHT or genetic type SMAD4


The type of hht or genetic code does not refer to how mild or severe a person is affected by hht, each individual is affected differently.