 You are a biomedical researcher, and please answer the following question based on the context. 
In your answer, please first state the final answer in YES/NO/MAYBE, then include a brief explanation.

### Question: Do all the patients with gastric parietal cell antibodies have pernicious anemia?

### Context: 1: This study evaluated whether all the patients with serum gastric parietal cell antibody (GPCA) positivity had pernicious anemia (PA).
2: The blood hemoglobin (Hb), iron, and vitamin B12 concentrations, and mean corpuscular volume (MCV) in 124 GPCA-positive patients were measured and compared with the corresponding data in 124 age- and sex-matched healthy controls. PA was defined by World Health Organization (WHO) as having an Hb concentration<13 g dl(-1) for men and<12 g dl(-1) for women, an MCV ≥ 100 fl, and a serum vitamin B12 level<200 pg ml(-1) .
3: We found that 20, 25, and 20 GPCA-positive patients had deficiencies of Hb (men<13 g dl(-1) , women<12 g dl(-1) ), iron (<60 μg dl(-1) ), and vitamin B12 (<200 pg ml(-1) ), respectively. Moreover, 16 GPCA-positive patients had abnormally high MCV (≥ 100 fl). GPCA-positive patients had a significantly higher frequency of Hb, iron, or vitamin B12 deficiency and of abnormally high MCV (all P-values<0.001) than healthy controls. However, only 12.9% of 124 GPCA-positive patients were diagnosed as having PA by the WHO definition.


###Response: Only 12.9% of GPCA-positive patients are discovered to have PA by the WHO definition.
 