Partial trisomy 16p in an adolescent with autistic disorder and Tourette's syndrome.

A partial trisomy 16p was identified in a 14-year-old male adolescent with autistic disorder. He additionally showed complex motor and vocal phenomena, including some simple tics which had first appeared in childhood. Whereas these simple tics were of subclinical significance, an additional diagnosis of Tourette's syndrome (TS) appears justified. The case report illustrates the diagnostic difficulties in assessing psychiatric symptomatology associated with both disorders, especially complex motor and vocal phenomena. The cytogenetic finding is discussed critically in the light of other chromosome abnormalities reported in both TS and autistic disorder. Chromosome 16p should be considered as a candidate region especially for autistic disorder.

Trisomy 21 is a recurrent secondary aberration in childhood acute lymphoblastic leukemia with TEL/AML1 gene fusion.

TEL/AML1 gene fusion is the most frequent genetic lesion in pediatric acute lymphoblastic leukemia (ALL). It occurs as a consequence of the cryptic chromosomal translocation t(12;21)(p13;q22). In a cohort of 50 RT-PCR-positive TEL/AML1 patients, karyotype examination by GTG banding and fluorescence in situ hybridization (FISH) allowed us to identify chromosome anomalies in addition to the already existing t(12;21). Secondary aberrations were found in 29 out of 41 patients (71%) at initial diagnosis and in all 9 patients with relapse. Structural rearrangements affected chromosome arms 2p, 2q, 5q, 9p, 12p (n = 2), 6q, 11p (n = 3), and 21q (n = 4). An extra chromosome 21 was found to be the most frequent anomaly. It was detected in 6 out of 41 patients at initial diagnosis (15%) and in 7 out of the 9 patients at relapse. No karyotype with trisomy 21 exceeded 47 chromosomes. Gain of chromosome 21 was the sole anomaly in GTG-banding analysis in 2/41 patients at initial diagnosis and in 4/9 at relapse. Notably, chromosome painting analysis performed in 11 out of the 13 patients with an extra chromosome 21 revealed duplication of the normal chromosome 21 in 8, and duplication of der(21)t(12;21) in 3 patients. Furthermore, gain of der(21)t(12;21) chromosome was confined exclusively to the relapse patients.