A rare occurrence of two large de novo duplications on 1q42-q44 and 9q21.12-q21.33

•We reported a patient carrying two large de novo interstitial duplications including a 20 Mb duplication at 1q42-q44 and a 14.2 Mb duplication at 9q21.12-q21.33. This type of case is quite rare.•We summarized the clinical characteristics of patients with distal 1q trisomy and patients with 9q21 duplication respectively.•We compared the phenotypes of distal 1q trisomy and 9q21 duplication.•We concluded that the distal 1q trisomy may have contributed to the features of macrocephaly, prominent forehead and limb abnormalities of our patient.•Either the distal 1q trisomy or the 9q21 duplication or both could have contributed to our patient’s clinical presentation of growth retardation, developmental delay and dysmorphic features including hypertelorism, low-set ears and abnormal nose/nasal bridge.

De novo partial distal 1q trisomy is uncommon and mostly occurs in combination with monosomy of another chromosome due to a parental translocation. Distal 1q trisomy co-occurring with another de novo duplication on a separate chromosome is extremely rare. Here, we reported a patient carrying two large de novo interstitial duplications including a 20 Mb duplication at 1q42-q44 and a 14.2 Mb duplication at 9q21.12-q21.33. The patient presented with features of pre- and postnatal growth retardation, low birth weight, failure to thrive, developmental delay and frequent infection. Her dysmorphic features included macrocephaly, prominent forehead, triangular face, wide fontanelle, hypertelorism, flat nasal bridge, tented mouth, micrognathia, protruding and low-set ears, slender limbs with toe-walking appearance. In addition, she presented with subdural hematoma. The clinical presentations of this patient are mostly consistent with those of distal 1q trisomy syndrome or 9q interstitial duplication. The interstitial 1q trisomy may have contributed to the macrocephaly, prominent forehead and limb abnormalities of our patient. Either or both de novo duplications could have contributed to the features of growth retardation, developmental delay and dysmorphic features including hypertelorism, low-set ears and abnormal nose/nasal bridge.