[Clinical and molecular analysis of two Chinese siblings with Bloom syndrome]

Objective: To expand the knowledge of the clinical and molecular characteristics of the children with Bloom syndrome. Methods: Clinical data of two siblings with classic Bloom syndrome of Shanghai Children's Medical Center from January 2009 to June 2017 were obtained and analyzed. The DNA of peripheral blood was collected from two Bloom syndrome siblings and their parents during 2015. The mutations were detected with high-throughput sequencing by Illumina sequencing platform. Results: The two siblings (probands) visited our department for short stature and growth retardation, they had full-term normal delivery after normal pregnancy of their mother. Both cases presented with feeding difficulties, malnutrition, microcephaly and mental retardation, repeated infection, symmetrical short stature and special faces. At first, the proband was an 8-year-3-month old girl, her height was 99.7 cm, body mass index (BMI) 12.07 kg/m(2), head circumference was 45.5 cm, and birth weight was 1.6 kg. Her younger brother was 3-year-11-month old, his height was 86.6 cm, BMI was 14 kg/m(2), birth weight was 1.95 kg, and the head circumference reached 36 cm at 16 months. No evidence of cancer and characteristic rash was detected at 8-year follow-up. Pathogenic complex heterozygous mutations c.772_773delCT, p.Leu258Glufs*7 and c.959+ 2T>A in BLM gene were detected in both siblings, which were separately inherited from their unaffected parents. Besides , c.959 + 2T>A has not been reported previously. Conclusions: Children with Bloom syndrome are characterized by short stature, microcephaly, special faces, feeding difficulties, and immunodeficiency. And butterfly erythematous rash may be absent. The c.959+2T>A mutation detected in our patients maybe a novel pathogenic mutation.