What is the most common chromosomal abnormality found in a newborn girl with lymphoedema and a low hairline?

The correct answer is associated with Turner syndrome, a condition that arises from the partial or complete absence of one of the two X chromosomes in females, leading to the karyotype of 45, XO. This chromosomal abnormality is characterized by a variety of physical features and health concerns, including lymphoedema, particularly noticeable in the hands and feet, and a low hairline, which are key indicators often observed in newborn girls with Turner syndrome.

In understanding why this is the most relevant choice, it's important to note that typically, individuals with Turner syndrome are often shorter than average and may have other developmental issues related to their physical characteristics. The presence of lymphoedema, among other traits like a low hairline, aligns closely with what is commonly seen in cases of Turner syndrome.

The other choices do not align with the typical presentations found in newborn females with these specific symptoms. For instance, karyotype 46 XX represents a normal female chromosomal arrangement, which would not account for the presence of lymphoedema or a low hairline. The 47 XXX condition, associated with Triple X syndrome, can lead to unique developmental traits but is less commonly linked with lymphoedema. The karyotype 46 XY