These next five are case studies:

Cerebral atrophy in a vitamin B12-deficient infant of a vegetarian mother:

https://www.ncbi.nlm.nih.gov/pubmed/25076673

Severe megaloblastic anemia in child breast fed by a vegetarian mother:

https://www.ncbi.nlm.nih.gov/pubmed/8442642

Consequences of exclusive breast-feeding in vegan mother newborn - case report:

https://www.ncbi.nlm.nih.gov/pubmed/19748244

Nutritional vitamin B12 deficiency in a breast-fed infant of a vegan-diet mother:

https://www.ncbi.nlm.nih.gov/pubmed/3948463

"We report the case of a 7 month-old girl that presented with acute anemia, generalized muscular hypotonia and failure to thrive. Laboratory evaluation revealed cobalamin deficiency, due to a vegan diet of the mother."

https://www.ncbi.nlm.nih.gov/pubmed/18293883

Most recent studies using more sensitive techniques for detecting B12 deficiency have found that 68% of vegetarians and 83% of vegans are B12 deficient, compared to just 5% of omnivores. https://www.ncbi.nlm.nih.gov/pubmed/12816782
https://www.ncbi.nlm.nih.gov/pubmed/10966896
https://www.ncbi.nlm.nih.gov/pubmed/10552882

On paper, calcium intake is similar in vegetarians and omnivores (probably because both eat dairy products), but is much lower in vegans, who are often deficient.
https://www.ncbi.nlm.nih.gov/pubmed/21139125
http://ajcn.nutrition.org/content/70/3/543s.full