There are two primary DNA databases were UID's are compared to MP's (or MP Family Reference Samples) - One is CODIS, which is run by the FBI, and the other is within the NamUs system. There are other state and private DNA databases, but they don't do comprehensive nationwide comparisons.
NamUs is run by the University of North Texas. So when a MP's DNA profile says "Sample Submitted - Tests Complete", I am pretty certain that the MP's DNA profile is at least in NamUs, although I am not so certain that that the sample is also in CODIS. CODIS will not accept samples from private labs, such as Bode Laboratories. Somewhere I've also heard that CODIS deals only with MP's who are thought to be victims of foul play. IIRC, if a person is missing as a result of circumstances, such as natural disaster, an accident, runaway or family abandonment, the person is not entered in CODIS. Also, from what I've heard, some state DNA databases automatically upload their MP DNA data to CODIS, and others don't.
But my understanding is that if the MP's DNA section in NamUs says Sample Submitted - Tests Complete, it at least is in NamUs for automated comparison.
I should add that an MP may have Mitochondrial DNA (mtDNA), or Nuclear DNA (nucDNA, sometimes referred to as STR), or both, depending on whether the familial contributors are mtDNA compatible (i.e., related by way of the maternal ancestral line) and also depending on how many Family Reference Samples are submitted. I've heard that NamUs and CODIS will not compare nucDNA based on only a single FRS.
So it may not be sufficient for both the MP and UID to have DNA in the system. The MP and UID need to both have the same type of DNA in the system, and if both have nucDNA, but one side does not have mtDNA, then there must be more than one FRS for the MP.
Or at least that's the way I understand it.