Who are at risk for developing nutritional vitamin D deficiency?

An 8-year-old male presents with concern for bilateral genu valgum deformity and complaint of pain in both lower limbs on walking or running. Parents note that he has always been the shortest boy in his class at school and his complaints of pain on walking and lower limb deformity have developed and progressed over the past six months. Patient and parents deny any trauma, and there is no history of fractures. Patient does not have any alopecia, or dental problems such as discoloration or abscesses. Patient has a history of polyuria and primary nocturnal enuresis.

Who are at risk for developing nutritional vitamin D deficiency?