A table from from Cerebral folate deficiency: Analytical tests and differential diagnosis:
The first column contains patient numbers.
I thought that sib of .. meant "sibship of .." - that is, "in the patient's family, there is a total of NUMBER sisters and brothers". But when I came across "sib of 18" and "sib of 20" I started having second thoughts. Are there really families with such huge numbers of children?
What could be an alternative meaning for the abbreviation sib here?