Teo S H, Tan M, Knight L, Yeo S H, Ng I
Department of Paediatric Medicine, Singapore General Hospital.
Ann Acad Med Singap. 1995 Mar;24(2):302-4.
Pericentric inversion of the chromosome 9, inv(9)(p11q13), is such a common occurrence that some cytogeneticists would consider them as normal variants. The incidence is said to be about 1% to 1.65% in the general population. Despite being categorised as a minor chromosomal rearrangement which does not correlate with abnormal phenotypes, many reports in the literature raised conflicting views regarding the association with subfertility and recurrent abortions, abnormal clinical conditions, as well as chromosomal abnormalities arising as a result of having this inversion. We studied the incidence and clinical significance of inv(9)(p11q13) patients retrospectively from 2448 antenatal cytogenetic analysis and 1058 peripheral blood karyotype collected over a 3-year period. Thirty cases of inv(9)(p11q13) from 29 families were found from the antenatal group, which gave an incidence of 1.2% and 6 cases from the peripheral blood karyotype analysis (incidence of 0.6%). The parental origin of the inv(9)(p11q13) in the antenatal group was of equal proportion and there was also no sex predilection for the fetuses carrying the inversion. The babies with the inversion were born with no phenotypic abnormalities. The 6 cases picked up from the peripheral blood karyotype analysis were 2 cases of paediatric patients with associated chromosomal abnormalities (one Trisomy 21 and the other del 13(q22q32)) and 4 adult patients with obstetric and fertility problems. The incidence of subfertility (36%) appeared to be high amongst the adult patients with inv(9)(p11q13). This may represent a true reflection of subfertility in inv(9)(p11q13) patients or a selective bias towards the older subfertile women who conceive at a later age and thus utilising the antenatal diagnostic setup.
9号染色体臂间倒位，inv(9)(p11q13)，是一种非常常见的情况，以至于一些细胞遗传学家会将其视为正常变异。据说在普通人群中的发生率约为1%至1.65%。尽管被归类为一种与异常表型无关的微小染色体重排，但文献中的许多报告对其与生育力低下、反复流产、异常临床状况以及由这种倒位导致的染色体异常之间的关联提出了相互矛盾的观点。我们回顾性研究了在三年时间里收集的2448例产前细胞遗传学分析和1058例外周血核型中inv(9)(p11q13)患者的发生率及临床意义。在产前组中，从29个家庭中发现了30例inv(9)(p11q13)，发生率为1.2%，在外周血核型分析中发现6例（发生率为0.6%）。产前组中inv(9)(p11q13)的亲代来源比例相等，携带倒位的胎儿也没有性别偏好。携带倒位的婴儿出生时没有表型异常。从外周血核型分析中检出的6例患者中，有2例是伴有染色体异常的儿科患者（1例21三体，另1例13号染色体长臂缺失(del 13(q22q32))），还有4例是有产科和生育问题的成年患者。inv(9)(p11q13)成年患者中的生育力低下发生率（36%）似乎较高。这可能真实反映了inv(9)(p11q13)患者的生育力低下情况，也可能是对年龄较大、生育力低下且晚育从而利用产前诊断检查的女性的一种选择性偏倚。
