Genetic linkage of the tricho-dento-osseous syndrome to chromosome 17q21

Tricho-dento-osseous syndrome (TDO), MIM# 190320, is transmitted as a highly penetrant autosomal dominant trait that is characterized by variable clinical expression. The principal clinical features include kinky/curly hair in infancy, enamel hypoplasia, taurodontism, as well as increased thickness and density of cranial bones. Possible genetic linkage has been reported for TDO with the ABO blood group locus, but the gene defect remains unknown. We have identified four multiplex families (n = 63, 39 affected, 24 unaffected) from North Carolina segregating TDO. We previously have excluded a major locus for TDO in the ABO region for these families. Utilizing a genome-wide search strategy, we obtained conclusive evidence for linkage of the TDO syndrome locus to markers on chromosome 17q21 (D17S791, Z max = 10.54, Theta = 0.00) with no indication of genetic heterogeneity. Multipoint analysis suggests the TDO locus is located in a 7 cM chromosomal segment flanked by D17S932 and D17S941. This finding represents the first step towards isolation and cloning of the TDO gene. Identification of this gene has important implications for understanding normal and abnormal craniofacial development of hair, teeth and bone.      

Loss of 14q and 22q in gastrointestinal stromal tumors (pacemaker cell tumors)

Gastrointestinal stromal tumors (GISTs), also referred to as “gastrointestinal pacemaker cell tumors (GIPACT)” are mesenchymal neoplasms that are phenotypically similar to the interstitial cells of Cajal (ICC). Cytogenetic studies of this entity are rare and molecular cytogenetic studies utilizing chromosome-specific probes are nonexistent. In the current study, cytogenetic and molecular cytogenetic analysis of 12 histologically and immunohistochemically confirmed GISTs revealed loss of a whole chromosome 14 or region(s) of 14q in 8 tumors evaluated (67%) and loss of a whole chromosome 22 or region(s) of 22q in 8 (67%) patients. Loss of 14q and 22q were observed in histologically benign and malignant GISTs. Structural rearrangements of chromosome 1 were observed in 2 malignant GISTs. These findings indicate that loss of 14q and 22q are nonrandom, early events in GIST tumorigenesis and suggest that tumor suppressor genes responsible for the development of this neoplasm may be located on these chromosomal arms.     

Identifying patients at low risk of death from cardiac failure after operation for postinfarct ventricular tachycardia

BACKGROUND: In unselected patients, cardiac failure accounted for most deaths after antiarrhythmic operation (ER) for postinfarction ventricular tachycardia (VT). This study aimed to determine whether patients at low risk of this outcome could be predicted from a retrospective analysis of variables from 100 consecutive ER patients. METHODS: Thirteen variables suggested by other researchers as predictive of outcome were analyzed. At the time of study, ER was the only therapy available for drug refractory VT. RESULTS: Only emergency ER, wall motion score less than 3 and Killip classification were significantly related to death from cardiac failure. The lack of correlation between emergency ER and variables of ER timing, VT less than 24 hours of ER or VT type implies that the need for emergency ER is also related to ventricular dysfunction. Multivariate analysis identified a group at particularly low risk of death with a specificity of 95%. CONCLUSIONS: Patients at low risk of death after ER can be identified prospectively. In the implantable cardioverter defibrillator era, elective ER is best reserved for such patients. Emergency ER may still be justified in younger patients without comorbidity who will die of VT without it.