Can't run simple PyQt5 application with Spyder

Question

Could someone review where's my error of that code?

import sys
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QMainWindow, QFormLayout, QLineEdit, QComboBox, QSpinBox, QGroupBox, QVBoxLayout, QDialogButtonBox


class MyForm(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        self.first = QLineEdit("Name")
        self.secnd = QLineEdit("Surname")        
        self.gendr = QComboBox()
        self.gendr.addItems(['Male','Female','Shemale'])
        self.age = QSpinBox()
        self.age.setMinimum(15)

        self.fgLayout = QFormLayout()
        self.fgLayout.addRow('First', self.first)
        self.fgLayout.addRow('Second', self.secnd)
        self.fgLayout.addRow('Gender', self.gendr)
        self.fgLayout.addRow('Age', self.age)

        self.setLayout(self.fgLayout)
        self.setWindowTitle("My Form") 
        self.setGeometry(500,300,250,150)



if __name__ == "__main__":
    def run_app():
        app = QtWidgets.QApplication(sys.argv)
        mainWin = MyForm()
        mainWin.show()
        app.exec_()
    run_app()

I run it but it result with blank window. I can't find an error besides looking thru examples with PyQt5 scripts. Maybe some component I use in a wrong way?

I've changed the recommended settings like described at this link [https://github.com/spyder-ide/spyder/wiki/How-to-run-PyQt-applications-within-Spyder] but still get error:

\Anaconda3\lib\site-packages\ipykernel\parentpoller.py:116: UserWarning: Parent poll failed.  If the frontend dies,
                the kernel may be left running.  Please let us know
                about your system (bitness, Python, etc.) at
                ipython-dev@scipy.org
  ipython-dev@scipy.org""")


Kernel died, restarting

This must be some installation issue. I've just uninstalled previous version of Anaconda and installed a new one (Windows 7 Sp1). It may be also something wrong with my code because those examples from above link works fine; I've just added some features.