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A female infant with multiple malformations and mental retardation was noted to have a rare de novo chromosome abnormality involving mosaicism with two cell lines, one with a ring chromosome 13, and the other with partial trisomy 13 owing to a complex rearrangement. Cytogenetic examination excluded the presence of a t(13q;13q) cell line and showed a cell line with a marker chromosome containing two chromosome 13 long arms joined together after deletion of a part (q11-->q14) of one of them. In addition, the absence of a cell line with two normal chromosomes 13 or a cell line with a t(13q;13q) implies that the ring (13) and the marker (13) arose from a single event at the first cleavage division. The two cell lines were present in different proportions in both peripheral blood lymphocytes and skin fibroblasts. The results of microsatellite characterisation clearly indicate the paternal origin and the absence of recombination, supporting the postzygotic origin of both the ring and the marker chromosome.

Fifty-five members of a family with the cancer family syndrome (CFS) were investigated for the following potential biomarkers for cancer proneness: (1) cytogenetics of peripheral blood lymphocytes and skin fibroblasts; (2) in vitro tetraploidy of dermal fibroblast monolayer cultures; (3) quantitative serum immunoglobulin determinations; (4) study of genetic linkage with respect to eight blood group markers including Kidd. Biological specimens were obtained from 14 patients affected with cancer, 21 subjects at risk, and 20 healthy subjects. None of the markers tested in this family, in order to identify a biomarker for the status of CFS gene carrier, was found to be useful. Our search for linkage to other biological markers (DNA RFLPs and NK cells) is in progress.

Analysis of haemoglobin chain synthesis was performed in 15 Apulian patients with Hb H disease and in their patients and offspring. The Apulian carriers of Hb H disease show a marked imbalance of alpha and beta chain synthesis (0.39 +/- 0.1) with variable clinical and haematological manifestations. However, we are dealing with an intermediate form similar to that described in Italians from other regions. A significant difference was found between the mean alpha/beta ratio values (0.81 +/- 0.13) of parents and offspring of Hb H patients and those of the normal controls (1.05 +/- 0.09); however, extensive overlapping between these two groups exists. These results have led us to the conclusion that the forms of alpha-thalassaemia found in Apulia are similar to the alpha defects observed in Sicily; in both cases, in fact, haemoglobin chain synthesis was an unreliable test for discriminating between alpha-thalassaemia-1 trait and alpha-thalassaemia-2 trait.

The cat eye syndrome (CES), usually ascribed to the presence of a deleted supernumerary 22 chromosome, is characterised by a typical clinical picture including anal atresia, ocular coloboma, preauricular tags or sinuses, congenital heart defects, urinary tracts anomalies, and mental and physical retardation. An analysis of published reports revealed that of the 57 reported cases, only 21 showed the complete form, and 11 had a normal karyotype. Several observations question the existence of a trisomy 22:(1) the absence of any report in living subjects of trisomy 22 arising from an inherited Robertsonian translocation; (2) the recurrent abortions in carriers of Robertsonian translocations involving chromosome 22; and (3) the existence of a syndrome, showing the same clinical features as trisomy 22, which is irrefutably dependent on a trisomy of the distal region of the 11 long arm. On the basis of a comparison of the clinical features in full trisomy 13, partial 13 trisomies, 13 rings, 13 deletions, and CES the small marker present in this syndrome is considered to be a chromosome 13 with an interstitial deletion. An attempt to map this chromosome has been made.