Inheritance

How common is Harlequin Ichthyosis?

Harlequin Ichthyosis (HI) is extremely rare, there are currently 10 people living with it in United States.

It is estimated that the occurrence of HI is 1 out of every 3 million births.

How do people inherit Harlequin Ichthyosis?

People inherit genes from their mother and father. When a disorder is autosomal recessive, the affected new-born’s cells will have mutated gene copies contributed from both biological parents. When someone has only one mutated gene copy in each cell, they are said to ‘carry’ the disorder and can pass it to their children.

HI is inherited in an autosomal recessive pattern, when both parents carry the mutated gene copy; the chances of the child being affected are the following for each pregnancy…

1 in 4 (25%) chance of having a child affected with Harlequin Ichtyosis

1 in 2 (50%) chance of having a child who carries Harlequin Ichthyosis

1 in 4 (25%) chance of having a child who is completely unaffected from HI