I also have a report by Dr. Tartaglia on girls with a chromosome anomaly.
There is also a type of ocular albinism that is carried on the X chromosome and occurs almost exclusively in males because they have only one X chromosome and, therefore, no other gene for the trait to override the defective one.
By studying the reading and writing abilities of close to 80 family members across four generations, the researchers reported, for the first time, that chromosome 2 can be involved in the inheritability of dyslexia.
However, it is estimated that 3 to 8 percent of girls with a single X chromosome and 12 to 21 percent of females with sex chromosome mosaicism may have normal pubertal development and spontaneous menstrual periods.
Mothers who have one mutated X chromosome and one normal copy have a 50 percent chance of passing the mutation to each child they bear, though they are very likely to show no symptoms of fragile X themselves.
Maternal uniparental disomy for chromosome 15 leads to PWS because the genes on chromosome 15 that should have been inherited from the father are missing, and the genes on both the chromosome 15s inherited from the mother are imprinted.
These individuals have had the unfortunate occurrence of a spontaneous mutation, meaning that in their early development, some random genetic accident affected their X chromosome, resulting in the defect that causes hemophilia A or B.
Female children, on the other hand, have two copies of the X chromosome, which often leaves them one normal X chromosome to fall back on to produce that essential protein, allowing proper development to occur.
Partial trisomy of the proximal segment of chromosome 13 is much less likely to be fatal and has been associated with a variety of facial features including a large nose, a short upper lip, and a receding jaw.
As they pass into this position they undergo a longitudinal splitting by which the chromatin in each chromosome becomes divided into equal halves.