The Y chromosome’s genetic puzzle is finally complete

The male sex chromosome can vary in length from person to person by millions of DNA bases

Illustration of a hand wearing a blue medical glove placing the final piece in a square puzzle that shows the letter Y.

Piecing together the human Y chromosome was tricky because of lots of repetitive DNA, but researchers have finally finished the whole puzzle.

N. Hanacek/NIST

The human Y chromosome, responsible for determining male sex, finally has gotten an end-to-end examination.

Researchers sequenced the chromosome, which contains many genes involved in sperm production and fertility, from a male of European descent.