One missing X chromosome can leave fingerprints too faint for phone scanners
Some women with Turner syndrome report that fingerprint sensors cannot read their fingertips. The ridges can be underdeveloped, likely a trace of fluid swelling before birth. It is one surprising ripple from a single missing X chromosome, which affects roughly one in 2,000 to one in 5,000 girls born worldwide.
Most people carry 46 chromosomes, including two sex chromosomes. In Turner syndrome a female has only one working X, or part of the second is missing. The error arises while a parent's egg or sperm forms, or during the embryo's earliest cell divisions; no environmental cause is known and the mother's age plays no role. The American endocrinologist Henry Turner described the condition in 1938, and in 1964 it was traced to chromosomes.
Many cases are mosaic, meaning only some cells lack the X, and these often show milder signs or none at all. Only about 40 to 50 percent are pure monosomy X. Large genetic databases such as the UK Biobank keep finding women with few classic features, suggesting the textbook picture may be rarer than once thought. In that sample, women missing the X in every cell averaged 145 centimetres tall, while mosaic women averaged 159.
Height offers a neat genetic lesson. A gene called SHOX, found on both X and Y chromosomes, drives bone growth. Having one copy too few, as in Turner syndrome, stunts the skeleton, producing short stature, shorter fingers and a small chin, while having extra sex chromosomes, as in Klinefelter syndrome, tends to make people unusually tall. Growth usually looks normal at birth and starts lagging from about 18 months.
Swelling of the lymph system before birth is thought to shape several other features, including a webbed neck, low-set ears, upturned nails and those faint fingerprints. About half of those affected have heart defects, and aortic dissection is six times more common than in the general population. Most have normal intelligence, though some find spatial tasks and mathematics harder.
Source: Turner syndrome
