Discussion
The results of the present study demonstrated that Mediterranean mutation was the most frequent mutation in icteric and non-icteric neonates with G6PD deficiency; this mutation has been observed in more than half of the newborns in both groups, between which the relative distribution was not statistically different; although the distribution of Chatham mutation was higher in icteric neonates, the difference was not significant (Table 1). Likewise, in an investigation in Italy on 23 infants with severe icter and G6PD deficiency, 39 cases of Mediterranean mutation have been reported (20). Comparison between the present study and other investigations indicate that the mutations observed in icteric newborns with G6PD deficiency have not been significantly different with those in non-icteric neonates with the same deficiency, and Mediterranean type of mutation has similarly been the most common mutation in non-icteric population with mentioned deficiency. Higher frequency of Cosenza negative in non-icteric compared to icteric group is the other notable point in the present study, indicating that the frequency of rare G6PD mutations is lower in icteric compared with non-icteric group (Table 1). What distingui-shes the present research is addressing neonatal jaundice among icteric and non-icteric newborns for the first time in Iran since the relationship between the mutation of G6PD gene and clinical manifestation have not been discussed so far in this country. In this study, the mean serum bilirubin level and hospital stay in icteric patients was not statistically significant for different types of mutation (Table 2). Similar to the present study, in an investigation by Ainoon et al. in 2004 on 128 Chinese male newborns with G6PD deficiency, no difference has been found between the incidence of neonatal icter, the mean serum bilirubin level and the percent of newborns in need of phototherapy and duration of phototherapy between the two most common types of G6PD gene mutations (21). Moreover, in another study by Pietra Pertosa et al. in 2001, more severe clinical phenotype has been reported in the carriers of Mediterranean mutation or A- variants (19). In the present study, the percent of exchange transfusion was higher in Mediterranean mutation compared with other mutations; however, the difference was not statistically significant. In addition, in this study neonates with Chatham mutation have been less in need of exchange transfusion and their clinical phenotype has been milder (Table 3). Studies conducted in Sari have revealed that the prevalence of Chatham mutation is higher in this region of Iran compared with other parts of the world and, hence, the prevalence of G6PD variants in this area is similar to that in Italy compared with other Mediterranean countries (16). Regarding the researches implemented, Mediterranean G6PD is the most common mutation in Iran and other tropical and semi-tropical regions (17).
Considering cases of Cosenza negative in our study, further evaluation on other mutations of G6PD gene and studies with larger sample size are recommended to determine the severity of icter in Mediterranean and the incidence of Chatham mutations.