Novel targets for the 18p11.3 amplification frequently observed in esophageal squamous cell carcinomas.

Amplification of DNA in certain chromosomal regions, with consequent over-expression of specific genes within these amplicons, plays a crucial role in the development and progression of human cancer. Since our previous comparative genomic hybridization (CGH) study revealed frequent amplifications at 18p in esophageal squamous cell carcinomas (ESC) cell lines, we focused on the identification of genetic target(s) within the 18p amplicon. In four cell lines having remarkable copy-number amplification with homogeneously staining region (HSR) pattern by fluorescence in situ hybridization (FISH), the smallest common region of overlapping covered approximately 3.5 Mb at 18p11.3. We screened 29 ESC cell lines to discern amplifications and expression levels of 14 known genes and 21 uncharacterized transcripts within the amplicon. Only four known genes, YES1, TYMS, HEC and TGIF showed amplification and consequent over-expression. These genes were amplified in several of primary ESCs. Moreover, resistance to transforming growth factor beta (TGFbeta)-induced growth inhibition was enhanced in four cell lines with amplification and expression of TGIF, which encodes the repressor for TGFbeta-activated transcription, appears to be involved in the progression of ESC. Taken together, these results suggest that YES1, TYMS, HEC and TGIF are likely to be candidate targets for 18p11.3 amplification and be associated with esophageal tumorigenesis.

A new mutation of the fukutin gene in a non-Japanese patient.

Fukuyama-type congenital muscular dystrophy (FCMD), Walker-Warburg syndrome, and muscle-eye-brain disease are clinically similar autosomal recessive disorders characterized by congenital muscular dystrophy, cobblestone lissencephaly, and eye anomalies. FCMD is frequent in Japan, but no FCMD patient with confirmed fukutin gene mutations has been identified in a non-Japanese population. Here, we describe a Turkish CMD patient with severe brain and eye anomalies. Sequence analysis of the patient's DNA identified a homozygous 1bp insertion mutation in exon 5 of the fukutin gene. To our knowledge, this is the first case worldwide in which a fukutin mutation has been found outside the Japanese population. This report emphasizes the importance of considering fukutin mutations for diagnostic purposes outside of Japan.

The Xq22 inversion breakpoint interrupted a novel Ras-like GTPase gene in a patient with Duchenne muscular dystrophy and profound mental retardation.

A male patient with profound mental retardation, athetosis, nystagmus, and severe congenital hypotonia (Duchenne muscular dystrophy [DMD]) was previously shown to carry a pericentric inversion of the X chromosome, 46,Y,inv(X)(p21.2q22.2). His mother carried this inversion on one X allele. The patient's condition was originally misdiagnosed as cerebral palsy, and only later was it diagnosed as DMD. Because the DMD gene is located at Xp21.2, which is one breakpoint of the inv(X), and because its defects are rarely associated with severe mental retardation, the other clinical features of this patient were deemed likely to be associated with the opposite breakpoint at Xq22. Our precise molecular-cytogenetic characterization of both breakpoints revealed three catastrophic genetic events that had probably influenced neuromuscular and cognitive development: deletion of part of the DMD gene at Xp21.2, duplication of the human proteolipid protein gene (PLP) at Xq22.2, and disruption of a novel gene. The latter sequence, showing a high degree of homology to the Sec4 gene of yeast, encoded a putative small guanine-protein, Ras-like GTPase that we have termed "RLGP." Immunocytochemistry located RLGP at mitochondria. We speculate that disruption of RLGP was responsible for the patient's profound mental retardation.