Kalayinia Samira, Shahani Tina, Biglari Alireza, Maleki Majid, Rokni-Zadeh Hassan, Razavi Zahra, Mahdieh Nejat
Department of Genetics and Molecular Medicine, School of Medicine, Zanjan University of Medical Sciences (ZUMS), Zanjan, Iran.
Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran.
J Clin Lab Anal. 2019 Feb;33(2):e22663. doi: 10.1002/jcla.22663. Epub 2018 Sep 26.
Trisomy 22 mosaicism is a rare autosomal anomaly with survival compatibility. Recognition of the complete trisomy 22 which is incompatible with life from the mosaic form is critical for genetic counseling. Affected mosaic cases have prevalent clinical presentations such as webbed neck, developmental delay, abnormal ears, cardiac disorders, and microcephaly. Phenotype of these patients is milder than full chromosomal aneuploidy, and the severity of the phenotype depends on the count of trisomic cells. We describe a 4-year-old boy with mosaic trisomy 22 from healthy parents and no family history of any genetic disorders in the pedigree.
The patient had determined dysmorphic clinical features including facial asymmetry, cleft palate, gastroenteritis, hydronephrosis, developmental delay, genital anomalies, dysplastic toenails, flattened nasal bridge, congenital heart defect, hearing loss, cryptorchidism, and hypotonic muscle. He is the first reported with hypothyroidism and larynx wall thickness in worldwide and the first with atrial septal defect (ASD) from Iran. Chromosomal analyses using G-banding indicated a de novo Mos 47,XY,+22(6)/46,XY(44) karyotype with no other chromosomal structural changes.
Our observations confirm the importance of cytogenetic analyses for determining the cause of congenital anomalies and provide a useful genetic counseling. In addition, due to the fact that some of mosaic trisomy 22 features are unavoidable such as CHD and general hypotrophy, we suggest including echocardiography test for early diagnosis during the clinical assessment.
22号染色体三体嵌合体是一种罕见的常染色体异常，具有生存相容性。将与生命不相容的完全22号染色体三体与嵌合形式区分开来对于遗传咨询至关重要。受影响的嵌合病例有常见的临床表现，如蹼颈、发育迟缓、耳部异常、心脏疾病和小头畸形。这些患者的表型比完全染色体非整倍体轻，表型的严重程度取决于三体细胞的数量。我们描述了一名4岁男孩，其父母健康，家系中无任何遗传疾病家族史，患有22号染色体三体嵌合体。
该患者具有确定的畸形临床特征，包括面部不对称、腭裂、肠胃炎、肾积水、发育迟缓、生殖器异常、趾甲发育不良、鼻梁扁平、先天性心脏缺陷、听力丧失、隐睾和肌张力低下。他是全球首例报道伴有甲状腺功能减退和喉壁增厚的病例，也是伊朗首例伴有房间隔缺损（ASD）的病例。使用G显带的染色体分析显示为新发的Mos 47,XY,+22(6)/46,XY(44)核型，无其他染色体结构变化。
我们的观察结果证实了细胞遗传学分析对于确定先天性异常病因的重要性，并提供了有用的遗传咨询。此外，由于22号染色体三体嵌合体的一些特征如先天性心脏病和全身发育不良是不可避免的，我们建议在临床评估期间包括超声心动图检查以进行早期诊断。
