Departamento de Genética, Hospital Infantil de México Federico Gómez, Calle Dr, Márquez 162, Col, Doctores, Del, Cuauhtémoc, 06720 México, D,F,, México.
BMC Med Genomics. 2014 Sep 15;7:55. doi: 10.1186/1755-8794-7-55.
Trisomy 1q and monosomy 3p deriving from a t(1;3) is an infrequent event. The clinical characteristics of trisomy 1q41-qter have been described but there is not a delineation of the syndrome. The 3p25.3-pter monosomy syndrome (MIM 613792) characteristics include low birth weight, microcephaly, psychomotor and growth retardation and abnormal facies.
A 2 years 8 months Mexican mestizo male patient was evaluated due to a trisomy 1q and monosomy 3p derived from a familial t(1;3)(q41;q26.3). Four female carriers of the balanced translocation and one relative that may have been similarly affected as the proband were identified. The implicated chromosomal regions were defined by microarray analysis, the patient had a trisomy 1q41-qter of 30.3 Mb in extension comprising about 240 protein coding genes and a monosomy 3p26.3-pter of 1.7 Mb including only the genes CNTN6 (MIM 607220) and CHL1 (MIM 607416), which have been implicated in dendrite development. Their contribution to the phenotype, regarding the definition of trisomy 1q41-qter and monosomy 3p26.3-pter syndromes are discussed.
We propose that a trisomy 1q41-qter syndrome should be considered in particular when the following characteristics are present: postnatal growth delay, macrocephaly, wide fontanelle, triangular facies, frontal bossing, thick eye brows, down slanting palpebral fissures, hypertelorism, flat nasal bridge, hypoplasic nostrils, long filtrum, high palate, microretrognathia, ear abnormalities, neural abnormalities (in particular ventricular dilatation), psychomotor developmental delay and mental retardation. Our patient showed most of these clinical characteristics with exception of macrocephaly, possibly due to a compensatory effect by haploinsufficiency of the two genes lost from 3p. The identification of carriers has important implications for genetic counseling as the risk of a new born with either a der(3) or der(1) resulting from an adjacent-1 segregation is of 25% for each of them, as the products of adjacent-2 or 3:1 segregations are not expected to be viable.
来自 t(1;3)的三体 1q 和单体 3p 是一种罕见的事件。三体 1q41-qter 的临床特征已被描述，但尚未确定该综合征的特征。3p25.3-pter 单体综合征（MIM 613792）的特征包括低出生体重、小头畸形、精神运动和生长发育迟缓以及异常面容。
一名 2 岁 8 个月的墨西哥混血男性患者因家族性 t(1;3)(q41;q26.3)导致的三体 1q 和单体 3p 而接受评估。发现了四名平衡易位的女性携带者和一名可能与先证者有类似影响的亲属。通过微阵列分析确定了受影响的染色体区域，患者的三体 1q41-qter 延伸 30.3Mb，包含约 240 个蛋白质编码基因，单体 3p26.3-pter 延伸 1.7Mb，仅包含 CNTN6（MIM 607220）和 CHL1（MIM 607416）基因，这两个基因与树突发育有关。讨论了它们对表型的贡献，关于三体 1q41-qter 和单体 3p26.3-pter 综合征的定义。
我们提出，当存在以下特征时，应特别考虑三体 1q41-qter 综合征：出生后生长迟缓、大头畸形、宽囟门、三角面、额骨突出、浓眉、下斜睑裂、远视、平鼻梁、鼻孔发育不良、长鼻梁、高腭、小下颌、耳部异常、神经异常（特别是脑室扩张）、精神运动发育迟缓和智力障碍。我们的患者表现出大多数这些临床特征，除了大头畸形，这可能是由于 3p 丢失的两个基因的杂合性不足的代偿作用。携带者的鉴定对遗传咨询具有重要意义，因为由于相邻-1 分离，每个携带者新生儿都有来自 der(3)或 der(1)的风险为 25%，而不期望相邻-2 或 3:1 分离的产物是可行的。
