Deletions of Xq and growth deficit: A review

Abstract

A critical review of the literature disclosed 44 cases with a 46,X,Xq- karyotype without apparent mosaicism. Of these, 17 were of normal height (compared to the respective population), 11 had a height of over 1 SD below the mean, and 16 had a height of over 2 SD below the mean with breakpoints between Xq13 and Xq25. Since patients of normal height occurred with breakpoints as proximal as Xq13 we conclude that there is no major "growth gene" on Xq distal to q13. The most likely explanation for the variable phenotypic effect of Xq- is to assume that growth gene(s) in Xp or proximal Xq are inactivated on such a chromosome with some variability similar to the variable spreading of X inactivation seen in some X-autosome translocations.

Pseudoisodicentric Xp Chromosome [46,X,psu idic(X)(q21.1)] and Its Effect on Growth and Pubertal Development

“…Support for this theory is the presence of two XIST genes on the aberrant X chromosome in both our cases, inactivating the whole i(Xp) chromosome, including the PAR region [22,23]. Inactivation of the PAR region would effectively cause monosomy and thus haploinsufficiency of the SHOX gene resulting in short stature [1,2,12,21]. This hypothesis is strengthened by the report of del Rey et al [24], in which a female patient is described with a trisomy of the SHOX gene, two copies of the XIST gene and a small deletion of Xq which resulted in tall stature.…”

“…A deletion of a portion of the long arm of the X chromosome can cause alteration of chromatin structure and induce spreading of the inactivation process to those genes on the inactive part of the X chromosome which are usually active (‘inactivation enhancement'). The degree of inactivation is correlated with the size of the deletion, with larger deletions of Xq being more critical [21]. The inactivation might then also reach the PAR regions.…”

Opposite deletions/duplications of the X chromosome: two novel reciprocal rearrangements

“…It is interesting to note that our first classification of the rearrangement in cases 3 and 4 was del(X)(q26). The fact that in a review of the Xq deletions, 33 high stature was present among cases with del(X)(q25-26), who also have primary/secondary amenorrhea, suggests that such deleted chromosomes might be class II rearrangements.…”

Trisomy Xq and Xp Deletion Phenotype in a Case with Primary Amenorrhea and Mosaic 45,X/46,X,der(X) Karyotype: Case Report

“…De ğiş ken fe no ti pin gö rül me sinin en önem li ne den le rin den bi ri, Xp ve ya Xq'nun prok si ma lin de ki ge li şim gen le ri nin ba zı X oto zom trans lo kas yon la rın da gö rü len yan lı X inak ti vas yonun da ol du ğu gi bi inak ti ve ol ma sı dır. 20 İkin ci olarak, Xq23-27 inak ti vas yon kon trol mer ke zi kri tik böl ge sin de ki kı rıl ma nok ta sı nın bir po zis yon et ki si gös ter me si dir. 20 Eğer kı rıl ma nok ta sı over le rin normal ge li şi mi ni sağ la ya cak gen ler üze rin de et ki li değil se, her iki X kro mo zo mu nun nor mal iş lev le ri ni ye ri ne ge tir dik le ri söy le ne bi lir.…”

“…20 İkin ci olarak, Xq23-27 inak ti vas yon kon trol mer ke zi kri tik böl ge sin de ki kı rıl ma nok ta sı nın bir po zis yon et ki si gös ter me si dir. 20 Eğer kı rıl ma nok ta sı over le rin normal ge li şi mi ni sağ la ya cak gen ler üze rin de et ki li değil se, her iki X kro mo zo mu nun nor mal iş lev le ri ni ye ri ne ge tir dik le ri söy le ne bi lir. Üçün cü ola rak ise eğer bu po zis yon et ki si di rekt ola rak over le rin ge lişi min den so rum lu olan gen le ri et ki ler se, fe no ti pik et ki ler gö rü le bi lir.…”