Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands.
Am J Med Genet A. 2012 Jan;158A(1):166-73. doi: 10.1002/ajmg.a.34350. Epub 2011 Nov 21.
Loss-of-function mutations of GLI2 are associated with features at the mild end of the holoprosencephaly spectrum, including abnormal pituitary gland formation and/or function, and craniofacial abnormalities. In addition patients may have branchial arch anomalies and polydactyly. Large, microscopically visible, interstitial deletions spanning 2q14.2 have been reported in patients with multiple congenital anomalies and intellectual disability. We report here on a patient with a mild holoprosencephaly spectrum phenotype (bilateral cleft lip and palate and abnormal pituitary gland formation with panhypopituitarism) and normal psychomotor development, who was found to carry a 1.3 Mb submicroscopic heterozygous deletion in 2q14.2, encompassing the GLI2 gene. We review the genotype and phenotype of previously published probands with GLI2 aberrations. Our findings confirm the association of haploinsufficiency of GLI2 and mild HPE spectrum features. Consistent with prior reports, we observed incomplete penetrance of the deletion in the family, illustrating the multifactorial etiology of holoprosencephaly spectrum features. In addition to the holoprosencephaly spectrum features, the proband had heterotaxy of the abdominal organs. Mutations in the known heterotaxy genes (NODAL, ZIC3 and CFC1) were excluded. The deletion contains five genes, in addition to GLI2, including the EPB4.1l5 gene. Based on findings in Epb4.1l5 mutant mice we hypothesize that Epb4.1l5 is a candidate gene for the heterotaxy observed in the proband.
GLI2 的功能丧失突变与无脑回畸形谱中轻度特征相关,包括异常垂体形成和/或功能以及颅面异常。此外,患者可能有鳃弓异常和多指畸形。在患有多种先天性异常和智力残疾的患者中,已经报道了跨越 2q14.2 的大的、显微镜下可见的、间质缺失。我们在此报告了一名具有轻度无脑回畸形谱表型(双侧唇裂和腭裂以及垂体形成异常伴全垂体功能减退)和正常精神运动发育的患者,发现其携带 2q14.2 中的 1.3Mb 亚微缺失,包含 GLI2 基因。我们回顾了以前报道的 GLI2 异常的先证者的基因型和表型。我们的发现证实了 GLI2 杂合功能不足与轻度 HPE 谱特征的关联。与先前的报告一致,我们观察到该缺失在家族中的不完全外显率,说明了无脑回畸形谱特征的多因素病因。除了无脑回畸形谱特征外,该先证者还存在腹部器官的异位。排除了已知异位基因(NODAL、ZIC3 和 CFC1)的突变。缺失包含 GLI2 以外的五个基因,包括 EPB4.1l5 基因。基于 Epb4.1l5 突变小鼠的发现,我们假设 Epb4.1l5 是先证者观察到的异位的候选基因。