【单选题】在窗体上画一个名称为Command1的命令按钮和3个名称为Label1、Label2、Label3的标签,然后编写如下程序段: Private x As Integer Private Sub Command1_Click( ) Static y As Integer Dim z As Integer n =10 z = n+z y=y+z x=x+z LabelCaption = x Label...
Porphyrias are a group of genetic diseases that result from defects in enzymes of the biosynthetic pathway from glycine to porphyrins; specific porphyrin precursors accumulate in erythrocytes, body fluids, and the liver.
B.
The most common form is acute intermittent porphyria. Most individuals inheriting this condition are heterozygotes and are usually asymptomatic, because the single copy of the normal gene provides a sufficient level of enzyme function.
C.
However, certain nutritional or environmental factors (as yet poorly understood) can cause a buildup of δ-aminolevulinate and porphobilinogen, leading to attacks of acute abdominal pain and neurological dysfunction.
D.
The symptoms of most porphyrias are now readily controlled with dietary changes or the administration of heme or heme derivatives.