You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Gene"].

Please return the output as a JSON object of the format: {"Gene": ["SSX", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A family with two consecutive nonsense mutations in BMPR1A causing juvenile polyposis. We describe a novel germline mutation of BMPR1A in a family with juvenile polyposis and colon cancer. This mutation consists of two consecutive substitutions (735-6 TG>AT) that cause two nonsense mutations (Y245X, G246X), inherited in an autosomal dominant fashion, on one parental chromosome. This mutation caused protein truncation, and represents a novel case of consecutive nonsense mutations in human disease.
{"Gene": ["BMPR1A"]}