Callen D F, Freemantle C J, Ringenbergs M L, Baker E, Eyre H J, Romain D, Haan E A
Department of Cytogenetics and Molecular Genetics, Adelaide Children's Hospital, South Australia.
Am J Hum Genet. 1990 Sep;47(3):493-8.
Nine cases are described of tetrasomy 18p resulting from the presence of an isochromosome 18p [i(18p)]. The initial diagnosis of i(18p) was by standard cytogenetic techniques and was confirmed by in situ hybridization with a biotinylated alphoid probe (L1.84) specific for the pericentric region of chromosome 18 and with a tritium-labeled chromosome 18 probe (B74) which hybridizes to the D18S3 locus situated at 18p11.3. The clinical features of the cases are summarized and shown to constitute a distinct and recognizable syndrome. Common features were low birth weight, a characteristic facies, neonatal hypotonia with subsequent limb spasticity, short stature, microcephaly, mental retardation, and seizure disorders. On the basis of size and cytogenetic banding a marker chromosome can be suspected to be an i(18p). In situ hybridization with the alphoid probe L1.84 provides confirmation of chromosome 18 origin. This more precise diagnosis will be an advantage in situations of pre- and postnatal diagnosis, since parents can be provided with a more confident prognosis for their child.
本文描述了9例因18号染色体短臂等臂染色体[i(18p)]导致的18号染色体短臂四体综合征病例。i(18p)的初步诊断采用标准细胞遗传学技术，并通过与针对18号染色体着丝粒区域的生物素化α卫星探针（L1.84）以及与位于18p11.3的D18S3位点杂交的氚标记18号染色体探针（B74）进行原位杂交得以证实。对这些病例的临床特征进行了总结，结果显示它们构成了一种独特且可识别的综合征。常见特征包括低出生体重、特殊面容、新生儿肌张力低下伴随后的肢体痉挛、身材矮小、小头畸形、智力发育迟缓以及癫痫障碍。根据大小和细胞遗传学带型，可怀疑标记染色体为i(18p)。使用α卫星探针L1.84进行原位杂交可确认其来源于18号染色体。这种更精确的诊断在产前和产后诊断中具有优势，因为可为父母提供关于其孩子更可靠的预后信息。
