How do I download the mitochondrial haplogroup datasets for human genetics online?
Hmmm, I am not experienced enough in biology or bioinformatics to truly understand the question, but I am guessing you want to download the FASTA file or genebank file containing the sequence of the accession number you listed above.
There are 2 ways to do this -

Using your browser, if you want to download a small sample of files. On the right hand side of your screen you can see the &quot;send to&quot; button on this link, click on it and choose the what's appropriate for you and then click on create file.

https://www.ncbi.nlm.nih.gov/nuccore/MT742594.1

If you familiar with Biopython and python programming you can download multiple files at once in whatever format you want, there is an easy script to do this and has been taken from Biopython's documentation on biopython.org
import os
from Bio import SeqIO
from Bio import Entrez
Entrez.email = &quot;A.N.Other@example.com&quot;  # Always tell NCBI who you are
filename = &quot;MT742594.1.gb&quot;
if not os.path.isfile(filename):
 # Downloading...

 net_handle = Entrez.efetch(

     db=&quot;nucleotide&quot;, id=&quot;MG762674&quot;, rettype=&quot;gb&quot;, retmode=&quot;text&quot;

 )
 out_handle = open(filename, &quot;w&quot;)

 out_handle.write(net_handle.read())

 out_handle.close()

 net_handle.close()

 print(&quot;Saved&quot;)

print(&quot;Parsing...&quot;)
record = SeqIO.read(filename, &quot;gb&quot;)
print(record)


You can make a list of the accession numbers of the sequences you want to download and pass the list in the id, if you are curious as to how the code works visit biopython.org .