Investigation of the imprinted domain located at the chromosomal deletion associated with Prader-Willi syndrome

Prader-Willi综合征（PWS）是一种以肥胖和智力低下为主要特征的疾病。大多数患者在15 q11-q13处具有相同的染色体缺失。缺失总是发生在父本染色体上，表明涉及基因组印记。我们发现一例15号染色体大片段缺失的重度PWS患者，其远端断裂点位于距普通PWS患者的共同断裂点约20 kb的端粒末端。使用培养的细胞从这个严重的病人，我们调查基因（EST）映射在额外的删除是否其中一些是印记。结果，我们发现这些基因至少在淋巴母细胞中没有印记。因此，我们无法获得证据表明印记域比想象的要大。上述数据最近发表在《临床遗传学》上。

Prader-Willi syndrome (PWS) is one of the famous diseases that are characterized by obesity and mental retardation. Most of the patients share the same chromosome deletion at 15q11-q13. The deletion always occurs on the paternal chromosome, suggesting involvement of the genomic imprinting. Although several imprinted genes has been discovered within this deletion, it has yet not known whether some additional imprinted genes exist outside of the deletion, "an imprinted domain".We found a severe PWS patient with a large chromosome 15 deletion and found that its distal breakpoint was located approximately 20kb more telomeric from the common breakpoint of that of the usual PWS patient. Using the cultured cells from this severe patient, we investigated genes (ESTs) mapped in the extra deleted whether some of these are imprinted. As a result, we found that none of these genes was imprinted at least in the lymphoblast cells. Therefore, we could not obtain the proof that indicates the imprinted domain was larger than thought. These above data have recently been published in Clinical Genetics.