Talk to Pediatrician on Microcephaly

My first baby was microcephaly(small brain) by birth... Pregnancy was normal.. Cousin marriage ha... ND he was mentally ND physically disabled 2 years lekin no speech not sitting onset of seizure hue ND within 2 days he passed away at age of I have ha healthy baby of 2 years he is completely normal no issue.... The doctors didn't told about the reason behind microcephaly he also had an MRI it was clear just indicated small brain... I want to conceive should I do should I get a genetic testing done?? To find that k ye genetic problem ha ya koi aur baat ha.. Ya mujhe ap baby plan Nae krna chahye