How is one diagnosed with MSUD? How does it progress?

Maple Syrup Urine Disease is diagnosed by a newborn screening program.  MSUD is part of all newborn screening tests in all 50 states. Below is a link of the National Newborn Screening Status from 2014. It will list off all of the chronic disease that are tested in newborns after birth.
National Newborn Screening Test Status 
Women can also test during pregnancy. They can do DNA testing or enzyme testing for the fetus cells, however the samples would be taken from the CVS or the aminocentesis of the fetus  (Star-G, Screening, Technology, and Research in Genetics). These are very invasive tests for the fetus and should be consulted by a doctor. Below is an image of how the test would be done during pregnancy.

Image taken from http://hrsbstaff.ednet.ns.ca/morrison/Advanced%20Biology%2012/adv_bio_12_karyotyping_assign.htm

 

However once a child is born the newborn screening test will be done. According to Healthline MSUD the newborn screening test is a blood test taken a few hours after birth and critical for a child who has MSUD.  The blood test indicates the high levels of amino acids in the body that were not broken down.  There are also cases where a newborn, who is tested within 12 hours after birth, can have a false negative  (Medical Home Portal).  It is important to take note of this if both parents are carriers and to pay close attention for other signs and symptoms. Once a baby has surpassed the newborn stage other symptoms may arise that would indicate MSUD. For instance, a urine analysis of a baby's urine. The urine analysis would indicate a high level of keto acids, which would cause the little one's urine to give off a maple syrup aroma. Hence where the disease got it's name. It is very important to catch MSUD, because an increase in amino acids can lead to brain damage and death.

What if I am a carrier? 
If one is worried that he/she is a carrier there are testing that can be done. They can test an individual's DNA and see if they posses the recessive mutated gene of MSUD. For more information on carrier testing and diagnosing check out MSUD Family and Support Group at http://msud-support.org/

Resources:
Giorgi, A. (2012). Maple Syrup Urine Disease (MSUD). Retrieved October 17, 2015.  

Heldt, K., Schawhn, B., Marquardt, I., Grotzke, M., & Wendel, U. (2005). Diagnosis of MSUD 
           by newborn screening allows early intervention without extraneous detoxification. 84(4), 
           313-316. Retrieved October 18, 2015, from Science Direct.  
 
 NEWBORN SCREENING. (2013, May 24). Retrieved from   
            http://www.newbornscreening.info/Parents/aminoaciddisorders/MSUD.html#10