biomedical sub test[kalplan 2001] Discussion is welcome!

zhangheng1020UID：2130513

A newborn vomits after each feeding of milk-based formula, and does not gain weight. Biochemical testing reveals  a severe  deficiency of galactose-1-phosphate uridyltransferase, consistent with homozygosity. If this condition goes untreated, what is the likely outcome for this patient?
A. Benign disease except for cataract formation
B. Chronic emphysema appearing in early adulthood
C. Chronic renal failure appearing in adolescence
D. Death in infancy
E. Gastrointestinal symptoms that remit with puberty

zhangheng1020UID：2130513

Explanation:
The  correct answer  is D.  Galactosemia occurs  in two  very different  clinical forms.  Deficiency of galactokinase  produces  very mild  disease  with  the  only  significant complication  being  cataract formation.  In  contrast, homozygous  deficiency  of  galactose-1-phosphate uridyltransferase  produces severe  disease  culminating in death  in infancy. In addition  to galactosemia and galactosuria, these patients  have  impaired renal tubular  resorption leading to aminoaciduria, gastrointestinal symptoms, hepatosplenomegaly,    cataracts,   bleeding   diathesis,   hypoglycemia,   and   mental   retardation. Pathologically,  the CNS  shows neuronal loss and  gliosis and the liver shows fatty change progressing to cirrhosis.
Benign disease with cataract formation (choice A) is characteristic of galactokinase deficiency
Chronic    emphysema   (choice   B)   is   not   associated   with   homozygous   galactose-1-phosphate uridyltransferase deficiency, but rather with alpha 1-antitrypsin deficiency.
Impaired  tubular  reabsorption (producing  aminoaciduria)  is  seen within  a  few  days or  weeks  of feeding  milk to  an infant with severe galactosemia,  as opposed to chronic renal failure appearing in adolescence (choice C).
Gastrointestinal   symptoms   (choice   E)   certainly  occur   in   homozygous   galactose-1-phosphate uridyltransferase  deficiency,  but they  would not  be expected  to remit  with puberty. Instead, most untreated  infants with  this disorder  show failure  to thrive  and die  in infancy  from wasting  and inanition.

zhangheng1020UID：2130513

A  20-year old female who  is 2 months pregnant remembers that she had phenylketonuria (PKU) as a child and  required  a special diet.  Tests confirm markedly elevated  maternal serum levels of phenylalanine and  phenylacetic acid.  Genetic  studies  have not  been  performed on  the  father.  What should  the physician tell the parents regarding the welfare of the child?
A. Childhood phenylalanine restriction is sufficient to protect the health of her child.
B. Further information is required to ascertain if the fetus is at risk.
C. The fetus is at no health risk if it is heterozygous for the PKU gene.
D. The fetus is at no health risk if phenylalanine levels are normalized by the third trimester.
E. The mother's hyperphenylalaninemia may have already harmed the fetus.