Discussion:
Structural chromosomal abnormalities causing pregnancy loss.
A female has suffered five consecutive miscarriages.Cytological study of her peripheral blood revealed 46,XX inv(1) (p32 q34) in all her cells and inversion (9) (p12 q12) in 30% of the studied cells. It is likely that the chromosome 1 abnormality is the cause of the woman's recurrent miscarriages.
a) Explain in words the nature of the woman's chromosome 1 abnormality.
b) Find an ideogram of human chromosome 1 and DRAW with key landmarks, the woman's chromosomes 1, paired during oogenesis' first meiotic prophase. LABEL key landmarks.
c) Suppose in 70% of meiosis there is a crossover somewhere in the region between bands p32 and q34. DRAW the gametic chromosomes 1 that would result from meiosis in which a single crossover occurred within band q 1.1.
d) What fraction of the gametes are likely to give rise to normal development, if the chromosome 1 abnormality is the only cause of gametic/zygotic non-viability?