Zlotogora J
The Rosa and David Orzen Human Genetics Clinics, Department of Human Genetics, Hadassah Medical Center, Hebrew University, Jerusalem, Israel.
Hum Genet. 1998 Apr;102(4):381-6. doi: 10.1007/s004390050708.
Mosaicism in germ cells has been recognized, over the past few years, as an important and relatively frequent mechanism at the origin of genetic disorders. There are two possibilities for the existence of such a mosaicism: one is that the mutation occurs in a germ cell that continues to divide. The other possibility is that the mutation occurs very early in a somatic cell before the separation to germinal cells and is therefore present both in somatic and germinal cells. Depending on various factors, such as the gene involved and/or the degree of mosaicism, the carrier of a somatic and germline mosaicism may be asymptomatic or may present with various symptoms of the disease. There are still relatively few reports in the literature in which the origin of germ-line mosaicism has been analyzed; nevertheless, they allow for a better insight into the mechanisms involved. In some diseases, such as osteogenesis imperfecta, new mutations are often present as asymptomatic somatic and germline mosaicism in one of the parents of the propositus. In other disorders, such as neurofibromatosis, somatic mosaicism is very rare in the parents of the propositus, perhaps since such mosaicism causes clinical symptoms. These differences are particularly important for genetic counseling in order to evaluate the risk for another affected child after the birth of the propositus.
在过去几年中，生殖细胞中的嵌合体已被公认为是遗传疾病起源的一种重要且相对常见的机制。这种嵌合体的存在有两种可能：一种是突变发生在一个持续分裂的生殖细胞中。另一种可能是突变发生在体细胞分离出生殖细胞之前的非常早期阶段，因此在体细胞和生殖细胞中都存在。取决于各种因素，如所涉及的基因和/或嵌合体的程度，体细胞和生殖系嵌合体的携带者可能无症状，也可能出现该疾病的各种症状。文献中对生殖系嵌合体起源进行分析的报道仍然相对较少；然而，这些报道有助于更好地了解其中涉及的机制。在某些疾病中，如成骨不全症，新突变在先证者的父母之一中常以无症状的体细胞和生殖系嵌合体形式存在。在其他疾病中，如神经纤维瘤病，先证者父母中的体细胞嵌合体非常罕见，这可能是因为这种嵌合体导致临床症状。这些差异对于遗传咨询尤为重要，以便在先证者出生后评估另一个患病孩子的风险。
