Mr. and Mrs. Kim, a couple in their late 50s, are concerned about their son, John, who is 14 years old. John is a tall, outgoing, cheerful-appearing adolescent, who is nevertheless nervous about having his parents accompany him as they seek advice about his possible problems. Mr. and Mrs. Kim have no other children.
John’s penis and testicles are small for a 14-year-old. His testicles have not matured with puberty, and retain the appearance of those of a child. Mr. Kim says that John has gotten into trouble with school authorities over fighting with other boys in gym class and in the school hallways. This is a new problem during the current school year, but there have been other behavioral difficulties earlier in John’s school career.
“People make fun of me,” John says. “I’m getting tired of it.”
On examination, it is noted that John’s legs are exceptionally long in proportion to his trunk, which is short and stocky. In addition to the small testicles and penis, John has gynecomastia. His facial features are those of a normal 14-year-old.
Mrs. Kim says little, but is clearly very agitated about her son. Mr. Kim does most of the talking, and he seems baffled and embarrassed. Extended history for the Kim family identifies no health problems with either parent. Mrs. Kim was 43 years old when she gave birth to John.
John is scheduled for lab tests to determine his hormone levels and also to have chromosomal testing.
QUESTIONS
1.     What is the likely diagnosis for John?
   A. Fragile X syndrome
   B. Klinefelter syndrome
   C. Down syndrome
   D. Turner syndrome
2.     What is the genetic mechanism responsible for John’s condition?
A.   Sex chromosome non-disjunction
B.   Autosomal non-disjunction
C.   Deletion of one X chromosome
D.   Presence of extra Y chromosome
3.     What recommendations would be made for John and his parents?
   A. Male hormone treatment
   B. Psychological counseling
   C. A support group
   D. All of the above
4.     If John undergoes genetic testing, what will it show?
It will show an extra x chromosome for John.
5.     Which of the following medical treatment is appropriate for John?
A.   Estrogen treatment
B.   Testosterone treatment
C.   Progesterone treatment
D.   No treatment required
6.     Which is a common feature in a patient with Klinefelter syndrome?
A.   Cryptorchidism
B.   Hyperandrogenism
C.   Precocious puberty
D.   Testicular atrophy
7.     Which of the following is associated with this disorder?
A.   Normal IQ
B.   Gynecomastia
C.   Webbed neck
D.   Coarctation of aorta
8.     Why do patients like John need to be followed for many years?
A.   They may develop schizophrenia
B.   Risk of breast cancer
C.   Risk of endocarditis
D.   Risk of peripheral vascular disease
9.    What type of disorder is this?
A.   Autosomal dominant
B.   X-linked dominant
C.   X-linked recessive
D.   Chromosomal disorder
10. Mention a similar condition related to X chromosome that affects females.