PMP22基因在17p11.2时的1.4Mb串联重复通常表现为遗传性感觉运动多发性神经病伴足部畸形,感觉神经性听力损失,中度发育迟缓,和步态紊乱。尚未报道单个家族中的超端化和明显的表型变异性。在一个家庭里,PMP22串联复制表现为身材矮小,感觉运动多神经病,震颤,共济失调,感觉神经性听力损失,在27岁的索引病例中,甲状腺功能减退,作为轻微的面部畸形,肌肉痉挛,耳鸣,意图震颤,迟钝运动障碍,和感觉运动多神经病的31岁的同父异母兄弟的指数患者,以及两个父亲的感觉运动多神经病和足部畸形。同父异母的兄弟还表现出了过度的情绪,以前在PMP22串联复制载波中未报告。所呈现的病例表明,串联重复17p11.2可能具有明显的家族内表型变异性,并且轻度的面部畸形,耳朵伸出和过度发育可能是该突变的罕见表型特征。面部畸形与PMP22串联重复之间的因果关系,然而,仍然是投机性的。
The 1.4Mb tandem-duplication in the PMP22 gene at 17p11.2 usually manifests as hereditary sensorimotor polyneuropathy with foot deformity, sensorineural hearing-loss, moderate developmental delay, and gait disturbance. Hypertelorism and marked phenotypic variability within a single family has not been reported. In a single family, the PMP22 tandem-duplication manifested as short stature, sensorimotor polyneuropathy, tremor, ataxia, sensorineural hearing-loss, and hypothyroidism in the 27 years-old index
case, as mild facial dysmorphism, muscle cramps, tinnitus, intention tremor, bradydiadochokinesia, and sensorimotor polyneuropathy in the 31 year-old half-brother of the index-patient, and as sensorimotor polyneuropathy and foot-deformity in the father of the two. The half-brother additionally presented with hypertelorism, not previously reported in PMP22 tandem-duplication carriers. The presented cases show that the tandem-duplication 17p11.2 may present with marked intra-familial phenotype variability and that mild facial dysmorphism with stuck-out ears and hypertelorism may be a rare phenotypic feature of this mutation. The causal relation between facial dysmorphism and the PMP22 tandem-duplication, however, remains speculative.