Novel compound heterozygous mutations for lipoprotein lipase deficiency. A G-to-T transversion at the first position of exon 5 causing G154V missense mutation and a 5' splice site mutation of intron 8.

We systematically investigated the molecular defects causing a primary LPL deficiency in a Japanese male infant (patient DI) with fasting hyperchylomicronemia (type I hyperlipoproteinemia) and in his parents. Patient DI had neither LPL activity nor immunoreactive LPL mass in the pre- and post-heparin plasma. The patient was a compound heterozygote for novel mutations consisting of a G-to-T transversion at the first nucleotide of exon 5 [+1 position of 3' acceptor splice site (3'-ass) of intron 4] and a T-to-C transition in the invariant GT at position +2 of the 5' donor splice site (5'-dss) of intron 8 (Int8/5'-dss/t(+2)c). The G-to-T transversion, although affecting the 11 nucleotide of the 3'-consensus acceptor splice site, resulted in a substitution of Gly(154) to Val (G154V; GG(716)C(-->)GTC). The mutant G154V LPL expressed in COS-1 cells was catalytically inactive and hardly released from the cells by heparin. The Int8/5'-dss/t(+2)c mutation inactivated the authentic 5' splice site of intron 8 and led to the utilization of a cryptic 5'-dss in exon 8 as an alternative splice site 133 basepairs upstream from the authentic splice site, thereby causing joining of a part of exon 8 to exon 9 with skipping of a 134-bp fragment of exon 8 and intron 8. These additional mutations in the consensus sequences of the 3' and 5' splice sites might be useful for better understanding the factors that are involved in splice site selection in vivo.

[Suspected primary tumor in the diaphragm revealing large cell carcinoma in the lung with sarcomatous change].

A 59-year-old female was admitted to our institute with coughing. A primary tumor of the diaphragm was suspected by chest X-ray, CT and angiograms preoperatively. Intraoperative findings also suggested a large primary tumor in the diaphragm with invasion to the lung, pericardium and liver. Therefore, we performed partial resection of the diaphragm, lung, pericardium and liver all together through a right thoraco-abdominal approach and the diaphragm was reconstructed using polyglycolic acid mesh. Histologically, the large tumor located mainly in the diaphragm was sarcomatous, with transposition from the carcinomatous cells to the sarcomatous cells. A large cell tumor of the lung was also confirmed. Immunohistologically, the diaphragm tumor was positively stained by keratin and by epithelial membrane antigen. In addition, desmosomes were demonstrated under electron microscopy studies. The tumor of this case was sarcoma in the diaphragm developed from a minor large cell tumor in the lung. Though commonly thought difficult to prove sarcomatous change development from large cell tumor in the lung, we were able to determine this clearly with immunohistology and electron microscopy.