Humans have 46 chromosomes, including 22 pairs of autosomes and 23 sex chromosomes. Chromosomes contain DNA wrapped around proteins called histones. Centromere attaches sister chromatids during cell division. Telomeres protect chromosome tips and gradually lose DNA over time
Rare type, about as common as 46,XY type. Usually caused by chimerism rather than nondisjunction. External genitalia usually ambiguous or masculinized. Right gonad more likely to contain testicular tissue. Uterus present in 90% of cases worldwide
WHS is caused by irregularities on chromosome 4p. First documented by Cooper and Hirschhorn in 1961. More common in females (1:2 ratio)
MDS is a heterogeneous group of clonal hematopoietic disorders affecting aging population. Characterized by peripheral blood cytopenias and hypercellular bone marrow. Affects one, two, or all three myeloid cell lineages. Can transform into acute myeloid leukemia in some patients
Rare genetic disorder caused by extra small supernumerary marker chromosome (sSMC). sSMC consists of multiple copies of chromosome 12's short arm. Syndrome was first described by Philip Pallister in 1977
Isochromosome is a chromosome with mirror-image arms. Forms through simultaneous duplication and deletion of genetic material. Can be identified as i(chromosome number)(centromeric breakpoint). Created during mitosis/meiosis through centromere misdivision or U-type exchange