may suffer irreversible brain damage resulting in a very low IQ. In addition,
she will develop other clinical features characteristic of PKU, such as, a pale
skin, blonde hair and blue eyes.
DISCUSSION OF CASE STUDY 15.2
The karyogram shows trisomy 21, the commonest cause of Down syndrome
(Box 15.4). Its frequency increases substantially in the fetuses of older women.
It is essential to obtain a karyogram of the child to determine whether the
cause is a Robertsonian translocation to aid genetic counseling, because it
tends to run in families, that is it is hereditable, while trisomy 21 is sporadic
in occurrence. The advice to Jane would be that her son is not a familial
Down syndrome child. However, if she wishes to have another child, she has
a greater risk of carrying a Down syndrome child than younger mothers and
so she should have cytogenetic testing of the baby during pregnancy.
CHAPTER 16
DISCUSSION OF CASE STUDY 16.1
A diagnosis of cystic fibrosis is usually made following a sweat test where
there is a high concentration of chloride, since 99% of cystic fibrosis patients
have concentrations of Cl– in their sweat exceeding 70 mmol dm–3. This test
could be performed on the siblings but cannot detect heterozygous carriers.
DNA diagnosis would detect children with cystic fibrosis and those who are
heterozygous carriers.
DISCUSSION OF CASE STUDY 16.2
Janice is suffering from adult, type 1, Gaucher’s disease. If untreated she will
become anemic, her hepatosplenomegaly will increase and bouts of severe
generalized pain in the body and limbs will occur with more intensity and
frequency. Degeneration of vertebral bodies and hip joints are common
leading to distortion of the spine and the need for hip replacement surgery.
She can expect bouts of anemia and recurrent pulmonary infections.
Treatment should consist of counseling to explain the nature of the disease,
analgesics for the bone pains, blood transfusions to relieve the anemia and
physiotherapy to keep the body mobile. Regular exercise, such as walking
and swimming, should be encouraged. The major treatment should be
intravenous enzyme therapy using A glucocerebrosidase to prevent the
visceral complications. With appropriate treatment, Janice can expect a life
of reasonable quality and length.
CHAPTER 17
DISCUSSION OF CASE STUDY 17.1
It is unlikely that Chris has cancer but rather benign prostate hyperplasia, as
indicated by the rectal examination. The PSA is slightly elevated. It would be
useful to monitor the level over a period of time as increasing concentrations
would require further investigation to ensure that the condition was not
becoming cancerous. If the benign hyperplasia begins to cause too much
discomfort, it may be necessary to hospitalize Chris for treatment.
DISCUSSION OF CASE STUDY 17.2
From Rebecca’s history, her consultant might be expecting to see a shadow
on the lung indicative of carcinoma. The hemoptysis is a strong indicator,
though some infectious diseases, such as tuberculosis, might also have this
effect. Rebecca has smoked for 30 years and although she stopped smoking
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