The significance of Mongolian spots for primary screening of Mucopolysaccharidosis

Abstract Background To explore the significance of Mongolian spots for the primary screening of mucopolysaccharidosis (MPS). Method In this study, the incidence, size, number, distribution, and regression of Mongolian spots in 225 patients diagnosed with MPS in China followed between 2020 and 2021 were retrospectively investigated, and compared with those in 209 normal newborns. Results The diagnostic age ranged from 0 to 32 years old with a median diagnostic age was 3 years old. Although the total incidence of MPS patients with Mongolian spots (73.78%) was higher than that in normal newborns (66.51%), there was no statistical significance. The incidence of Mongolian spots ≥ 2 or ≥ 5 in MPS group was significantly higher than that in control group (P < 0.001). The average number of Mongolian spots in MPS patients at least greater than or equal to (2.84 ± 2.47) was higher than that in normal newborns (1.09 ± 1.33) with a significant difference (P < 0.001). The age of diagnosis with less than 2 Mongolian spots (median diagnostic age = 4.00) was later than with greater than or equal to 2 Mongolian spots (median diagnostic age = 3.00) in MPS group (z=-3.103, P = 0.002). The age of diagnosis with less than 5 Mongolian spots (median diagnostic age = 4) was later than with greater than or equal to 5 Mongolian spots (median diagnostic age = 3) in MPS group (z=-2.728, P = 0.006). Comparing MPS groups (median maximum length = 7.0cm) and control groups (median maximum length = 3.0cm), the two groups were statistically different (z=-7.801, P < 0.001). In MPS group, Mongolian spots were mainly distributed in the buttocks (81.93%) and back (68.07%), followed by the lower limbs (27.71%), abdomen (22.29%), and upper limbs (19.88%), with fewer distribution in areas such as the head, face, neck, and chest. Among the MPS patients born with Mongolian spots, there were 19.28% of patients had the disappearance of Mongolian spots by the time of investigation. Conclusions This study demonstrated Mongolian spots were a common feature in patients with MPS, especially in type 2, 1, and 6. Extensive Mongolian spots might be an indicator for early screening of MPS.