Question

A rare deletion on the long arm of chromosome 15 (15q11-13) produces one of two types of genetic disorders in humans. These are Prader-Willi syndrome (obesity, hypotonia, hypogonadism) and Angelman syndrome (epilepsy, tremors, perpetual smiling). Three imprinted genes are present in the deleted region. These are snrpn and ndn (lack of which is associated with Prader-Willi) and ube3A (lack of which is associated with Angelman). snrpn and ndn are paternally imprinted for expression and ube3A is maternally imprinted. Charlie and Pat are siblings both with Angelman syndrome and Charlie has one (of two) child with Prader-Willi Syndrome while Pat has a child with Angelman syndrome. What are the sexes of Charlie and Pat? Explain your answer. Can Charlie and Pat have two normal parents or does one of them have Prader-Willi or Angelman syndrome. Explain your answer and if one of them has a disorder tell me which parent had which disorder

Answer 1

To solve the question basic you need to know about the question has mentioned in the attached image below.

-1) ----'Charlie must be female

As we can see child of Charlie has prader villi syndrome.

In this condition mother gene is imprinted ( which is normally active , father gene is always imprinted) . So if her child has prader villi than she is having imprinted snmp and ndn gene and causing the disease in the child

--- Pat must be male  

His child having angelman syndrome.

As gene ube3A, is imprinted from mother side so mother dies not cause or impart disease. Ths active gene is actually provide by father . So in case of imprinting of father gene lead to angelman syndrome. So pat must be father and having imprinted ube3A gene and causing angelman syndrome in the child.

2) no they don have normal parents

Charlie has prader villi

Pat has angelman

So their mother must have imprinted Gene's of snmp and ndn. , so she impart prader villi to children

While father must have ube3A, and father impart angelman to the children.