We describe a female infant with mental retardation and some of the phenotypic features of Williams-Beuren syndrome. Chromosome analysis showed t(X;21)(q28;q11). Diagnosis, inactivation of the X chromosome, and possible involvement of the translocation breakpoints in the pathogenesis of this syndrome are discussed.

A man aged 34, whose mental retardation and appearance were consistent with the fra(X)(q28) syndrome, had a craggy lump in his left testis. The fragile X was found in lymphocytes, fibroblasts, and bone marrow. The testicular tumour was benign and inflammatory in nature and within the testis spermatogenesis was absent.

The gene has not been fully cloned at the present time. A 476-base novel sequence fused to AML1 has been identified and sequenced as a result of the molecular cloning of the t(4;21)(q28;q22). The novel sequence maps to chromosome band 4q28. Sequence analysis did not show any significant homology with any of the known genes in the human GenBank DNA database. However the first 118-bases are ident...

Interstitial deletions of the long arm of chromosome 4 are rare. The deletions may occur at the proximal or the distal portions of the chromosome and different breakpoints may be involved. We report an interstitial deletion of 4q: 46XY der 4 (q28;q35) in a six-year-old boy with dysmorphic features associated with moderate mental retardation. Parental chromosomal analysis showed a balanced pater...

If an unlimited number of processors is available, then for any given number of steps s, s >1, polynomials of degree as large as q28-6 can be evaluated, where C= V2 and 6: \V2s. This implies polynomials of degree can be evaluated in log2n+V/2 log2n +0(1) steps. Various techniques for the evaluation of polynomials in a "reasonable number" of "steps" are compared with the known lower bounds.

Telvi et al' recently reported on a 27 month old girl with an unbalanced de novo translocation, t(X;21)(q28;ql 1), and diagnosed this child as having an incomplete form of Williams-Beuren syndrome (WBS). This was based on some symptoms specific to WBS, such as craniofacial dysmorphism, delayed psychomotor development, short stature, horseshoe kidneys, and a positive WBS score of + 4.09.2 We do ...

Objective The Subtelomeric rearrangements are increasingly being investigated in cases of idiopathic intellectual disabilities (ID) and congenital abnormalities (CA) but have also been suspected to be responsible for unexplained recurrent miscarriage (RM). We have noticed a higher risk of subtelomeric translocations in association with CA and ID. Such rearrangements can go unnoticed through con...

A mother and daughter are described with premature menopause and deletion of the X chromosome at q28. Structural anomalies of the X chromosome and ovarian failure are well known.' Secondary amenorrhoea, recognised as premature menopause and involving an X chromosomal deletion, has only been described on two occasions, the breakpoints being at q252 and q26.3 We describe familial inheritance of a...

A DNA fragment (named St14) derived from the human X chromosome reveals a small family of related sequences that have been mapped to the Xq26-Xq28 region by using a panel of rodent-human somatic cell hybrids. The probe detects in human DNA digested by Taq I a polymorphic system defined by a series of at least eight allelic fragments with a calculated heterozygosity in females of 80%. With Msp I...