Daniel A, Lyons N, Casey J H, Gras L
Hum Genet. 1980;54(1):31-9. doi: 10.1007/BF00279046.
Two women with primary amenorrhoea and few other stigmata of Turner's syndrome were found to be chromosome mosaics: 45,X/46,X,idic(Y). In Case 1, the dicentric isochromosome Y was found to have a long-arm breakpoint of formation. This structure was interpreted as containing two Y short arms and centromeres separated by a region derived from the proximal Y long arm. One of the centromeres in the Case 1--idic(Y) was suppressed in 80% of cells in blood, and in these cells it appeared as a regular Y-shaped chromosome. In Case 2 the idic(Y) was derived by a short-arm breakpoint of formation. In all the dicentrics of this case with one primary constriction (functional monocentrics) there was a single Cd band. In the 10% of dicentrics with two primary constrictions, there were two Cd bands. It is argued that the instability of sex isochromosomes is due to this functional dicentricity in some cells. These cases are compared with 42 other Y isochromosomes with various short- and long-arm breakpoints of formation. It is suggested that some of the nonheterochromatic, nonfluorescent Y chromosomes previously reported may be explained as dicentric i(Y) with proximal long-arm breakpoints of formation and one suppressed centromere.
45,X/46,X,idic(Y)。在病例1中，双着丝粒等臂Y染色体被发现有一个形成的长臂断点。这种结构被解释为包含两个Y短臂和着丝粒，由来自近端Y长臂的一个区域隔开。病例1的idic(Y)中的一个着丝粒在血液中80%的细胞中被抑制，在这些细胞中它呈现为一条规则的Y形染色体。在病例2中，idic(Y)由一个形成的短臂断点产生。在该病例所有具有一个初级缢痕（功能性单着丝粒）的双着丝粒中都有一条单一的Cd带。在10%具有两个初级缢痕的双着丝粒中，有两条Cd带。有人认为性等臂染色体的不稳定性是由于某些细胞中的这种功能性双着丝粒。将这些病例与其他42条具有各种形成的短臂和长臂断点的Y等臂染色体进行了比较。有人提出，先前报道的一些非异染色质、非荧光的Y染色体可能被解释为具有近端长臂形成断点和一个抑制着丝粒的双着丝粒i(Y)。
