Children with TOF may develop acute episodes of hypoxia, known as Tet spells, during activities that demand more oxygen.

法儿童时，需增多，可出现急性缺发作，又称Tet spells。

The cause of tof remains largely unknown, but several genetic disorders and prenatal factors are thought to be associated with increased risks of this condition.

法原因还不清楚，但是认为一些基因异常和胎儿期因素与其有关。