Gene spectrum analysis of thalassemia for people residing in northern China

Southern China provinces have high incidence of thalassemia, however, sporadic cases can be found in northern China as well. People resided in north China who were suspected to have thalassemia were detected mutations by gap-polymerase chain reaction (Gap-PCR) and reverse dot blot (RDB) analyses. Those with positive findings from 2012 to 2017 were further analyzed for basic clinical data and ancestral information either by medical records or by telephone follow-up or both. Most people enrolled in our study had no or mild symptoms. For those with positive gene findings, people originated from the north had higher percentage of β-thalassemia gene mutations compared with those originated from the south (72.8% vs. 62.4%, χ = 9.92, P = 0.001). Analysis of the individual gene distribution of people from south and north areas did not show significant difference either in α- thalassemia (P = 0.221) or β-thalassemia (P = 0.979). No significant difference was found in the frequency of α mutation in people living in different altitudes. However, for β-thalassemia, the frequency of the 6 most common mutations was significantly different in people living in different provinces with altitude below 500 m, 500-1000 m, and above 1000 m (χ test, P