The main stem of the Bay itself is about 189 miles (304 km) long, from the Susquehanna River in the north to the Atlantic Ocean in the south. At its narrowest point near Annapolis, Maryland, the Bay is 4 miles (6.4 km) wide; at its widest point, near the mouth of the Potomac River, it is 30 miles (50 km) wide.
Patau syndrome. Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects.
Like Patau syndrome, Down syndrome is caused by having an extra copy of a certain chromosome. Individuals with Down syndrome usually have an extra copy of chromosome 21. Thus, Down syndrome is commonly called trisomy 21. Perhaps not surprisingly, the cause of the trisomy in both Patau and Down syndromes is similar. A phenomenon called nondisjunction is responsible for most cases of trisomy 13 and 21.