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We report a child with a duplication-deficiency subsequent to t(15;20)(q25.2;p12.2), transmitted in at least 5 generations, who showed features of 15q- syndrome. We speculate that brachydactyly--most likely because of brachymesophalangism--is a feature of the phenotype of this chromosomal aberration and points to candidate gene(s) in this region. A similar brachydactyly was, however, reported with dup(20p1-pter).

Two new cases of del(2)(q37.1) and one case of partial trp(2)(q37) are studied by FISH with cosmid probes from the COL6A3 and PAX3 genes mapped in 2q37.3 and 2q36, respectively. While the PAX3 gene dosage appeared unaffected, the COL6A3 gene was found to be deleted and triplicated, respectively. This finding could explain features of connective tissue disorders such as joint laxity and hypotonia or joint stiffness and epiphyseal dysplasia, particularly documented by congenital dislocation of the radial head. Karyotype-phenotype correlations with reference to published cases are discussed.

We report two cases with partial trisomy of 10q24.1-ter with concomitant deficiency of 7pter and 4qter, which share aplasia of the optic nerve and malformation of the anterior chamber. A review of published observations of partial trisomies of 10q showed that abnormalities of the eye, and particularly of the orbital region, are frequent, but ophthalmological studies are lacking. We conclude that our findings demonstrate a major effect of this chromosomal imbalance.

A single mandibular incisor and an unusually narrow mandible and tongue were noted in an 8-year-old moderately retarded boy with 18p- (45, XY, der dic (18) (18qter-p11.2::22p 11.2-qter). While a single maxillary incisor, considered a minor feature of holoprosencephaly, was reported in three cases of 18p-, reduction of mandibular incisors has been a very rare finding and has never been noted in similar cases.

Three children are reported with typical cat eye syndrome (CES) and three more children with partial CES because of absence of coloboma, in which the supernumerary marker chromosome was studied by FISH. Using a genomic library, and also a centromeric and particularly a cosmid probe of 22q11, partial tetrasomy was shown in all cases.

In seven cases additional minute chromosomes studied by FISH were identified as no. 3, 11, 15, 18, 21 and X. Findings were unexpected except for partial trisomy 21 in an adolescent with minor features of Down's syndrome. Moreover, an i(18p) in a mentally retarded dysmorphic child and an idic(15) in a child with Fallot tetralogy was confirmed. In a child with r(21), a supernumerary marker was shown to be derived from no. 21, while in the mother an additional marker idic(22) was noted.

Synostoses of the carpals and metacarpals with oligodactyly were noted in a man whose brother was similarly affected. Since the proband's two children are normal, autosomal recessive transmission is probable. Although abnormalities of the feet, and particularly radioulnar synostosis, are lacking, this malformation is comparable to the Cenani-Lenz type of syndactyly. Interfamilial variations of published cases suggest subdivision of a new nosologic group.

Partial trisomy of the distal portion of the long arm of chromosome no. 21, resulting from a (familial) translocation between the chromosomes no. 19 and 21 in a female twin with Down's syndrome, supports the hypothesis that triplication of 21q22 is the cause of the physical signs of mongolism. Partial trisomy of the remaining segments of chromosome no. 21 due to a (familial) translocation between the chromosomes no. 4 and 21, however, may only cause mental deficiency.

Deletion of the long arm of chromosome 8 was found in a mentally retarded boy with typical features of the Langer-Giedion syndrome (TRP syndrome type II). Additional malformations were colobomata of the iris and partial syndactyly of the 4th and 5th fingers.