From Dust, a Flame - Rebecca Podos

Rebecca Podos, Lambda Award-winning author of Like Water, returns with a contemporary Jewish fantasy of enduring love, unfathomable loss, and the power of stories to hold us together when it seems that nothing else can.
Hannah's whole life has been spent in motion. Her mother has kept her and her brother, Gabe, on the road for as long as she can remember, leaving a trail of rental homes and faded relationships behind them. No roots, no family but one another, and no explanations.
All that changes on Hannah's seventeenth birthday when she wakes up transformed, a pair of golden eyes with knife-slit pupils blinking back at her from the mirror-the first of many such impossible mutations. Promising that she knows someone who can help, her mother leaves Hannah and Gabe behind to find a cure. But as the days turn to weeks and their mother doesn't return, they realize it's up to them to find the truth.
What they discover is a family they never knew and a history more tragic and fantastical than Hannah could have dreamed-one that stretches back to her grandmother's childhood in Prague under the Nazi occupation, and beyond, into the realm of Jewish mysticism and legend. As the past comes crashing into the present, Hannah must hurry to unearth their family's secrets in order to break the curse and save the people she loves most, as well as herself.