Currants or gooseberries can have deformed leaves or canes because of herbicide injury, witches broom, or viruses.
Herbicide damage can cause abnormal shoot growth, multiple shoots from one location, and oddly shaped leaves.
The cause for this witch's broom is not known. This abnormal shoot growth may be caused by a phytoplasma but this needs to be confirmed. These photos were taken of symptoms in a swamp gooseberry, Ribes lacustre (Pers.) Poir., in a cultivated collection in Corvallis, Oregon.