Tricho‐rhino‐phalangeal syndrome type I (TRP I) due to an apparently balanced translocation involving 8q24

Abstract

Tricho-rhino-phalangeal (TRP) syndromes type I and II are caused by a defective gene located on chromosome 8q24.1. We report a family with 2 sibs affected with TRP type I in combination with an apparently balanced chromosome (8;18) translocation involving 8q24.11. It is very likely that the 8q24 translocation breakpoint is physically linked to the TRP gene(s), thereby facilitating future efforts to clone the TRP gene(s).

Loss of chromosome band 8q24 in sporadic osteocartilaginous exostoses

“…Buhler et al (1987) suggested that whether TRP I or T R P I1 develops depends on how much material is lost from 8q24.1; loss of 8q24.12 only leads to T R P I whereas loss of 8q24.11-.13 results in T R P 11. T h e findings of Marchau et al (1993), who described a seemingly balanced translocation t(8; 18) involving subband 8q24.11 in two sibs with TRP I, contradict this hypothesis, however. It nevertheless seems reasonable to include TRP I and I1 among the contiguous gene syndromes which are caused by microdeletions leading to different malformations, depending on the type and amount of genetic material lost (Schinzel, 1988).…”

Phenotype and genotype in 103 patients with tricho-rhino-phalangeal syndrome

“…The identification of an interstitial deletion involving chromosome 8q24 in an individual with TRPS II [Bühler et al, 1984] and subsequently a balanced translocation involving 8q24.1 in two individuals with TRPS I [Marchau et al, 1993] were the first steps in the localisation of the entities. In 2000 mutations in the zinc finger transcription factor TRPS1 were described in TRPS I [Momeni et al, 2000].…”

Trichorhinophalangeal Syndrome

“…For the TRPS, an autosomal dominant mode of inheritance with variable expression (MIM 190350) as well as a recessive form of inheritance (MIM 275500) have been suggested |4. 14,28], Patients who additionally show multiple cartilagi nous or bony exostoses are classified as TRPS type II or the Langer-Giedion syndrome [19,26], However, it is contro versial if TRPS I and II really present two separate entities [26], In some patients, a lesion of the long arm of chromo some 8 has been described [7,23,25,26,29], and it has been proposed that TRPS, in analogy with the Prader-Willi syndrome (MIM 176270), could be divided into a subtype with and one without a structural chromosomal lesion [29]. Chromosomal analysis was not performed in our patient.…”