Gaucher disease probability problem

What is Gaucher disease? Gaucher disease is a rare genetic disorder passed down from parents to children (inherited). When you have Gaucher disease, you are missing an enzyme that breaks down fatty substances called lipids. Lipids start to build up in certain organs such as your spleen and liver. This can cause many different symptoms. Your spleen and liver may get very large and stop working normally. The disease can also affect your lungs, brain, eyes, and bones. There are 3 types of Gaucher disease: Type 1. This is the most common type of Gaucher disease. It affects about 90% of people with the disease. If you have type 1, you don’t have enough platelets in your blood. This can make you bruise easily and feel very tired (fatigued). Your symptoms can start at any age. You might have an enlarged liver or spleen. You may also have kidney, lung, or skeletal problems. Type 2. This form of the disease affects babies by age 3 to 6 months. It is fatal. In most cases children don’t live beyond 2 years old. Type 3. Symptoms include skeletal problems, eye movement disorders, seizures that become more obvious over time, blood disorders, breathing problems, and liver and spleen enlargement. What causes Gaucher disease? Gaucher disease is passed down from parents to children (is inherited). It is caused by a problem with the GBA gene. It is an autosomal recessive disorder. This means that each parent must pass along an abnormal GBA gene for their child to get Gaucher. Parents may have only 1 GBA gene and, therefore, not show any signs of the disease, but be carriers of the disease. Gaucher disease type 1 is most commonly found among Ashkenazi Jews who have a high number of carriers of the defective GBA gene. Problem: Gaucher disease is an early onset rare autosomal recessively inherited lysosomal storage disorder (LSD). An adult woman who has no symptoms but has two affected brothers is referred for genetic counseling. Which of the following is correct? A) With two affected brothers the probability of her being a carrier is 1. B) Before any carrier testing is carried out the woman can be correctly informed that the probability that her first son will be affected is 1 in 4. C) If she is a carrier then the probability that each of her sons and each of her daughters will be affected is 1 in 4. D) The probability that she is a carrier is 1/2 E) The probability that she is a carrier is 2/3