Ear and hearing in relation to genotype and growth in Turner syndrome
Introduction
Turner syndrome (TS) is caused by a total or partial deletion of either X chromosome and occurs in one out of 2000–3000 liveborn girls (Gravholt et al., 1996). Genetically, the karyotypes in TS are divided into three main categories: (1) monosomy 45,X, having one X chromosome only in all cells, (2) those having 46 chromosomes in all cells but with a part of the sex chromosome deleted (46,XXdel or 46,XYdel) and (3) those having a mosaicism of cells with a varying number of sex chromosomes, as some cells may have a normal set of 46 chromosomes while others are monosomic 45,X. A reduced receptor sensitivity to growth hormone is one important mechanism in TS, the main characteristics of which are short stature, failure to enter puberty and an accelerated rate of atresia of ovarian follicles causing gonadal insufficiency and infertility. Auricular malformations, otitis media and sensorineural hearing loss are common (Watkin, 1989). It has repeatedly been suggested that the ear and hearing disorders in TS are due to the lack of genes on the X chromosome. It was recently verified that TS females with monosomy 45,X exhibited more severe hearing loss and a higher occurrence of auricular anomalies and recurrent otitis media than TS cases with mosaicism and structural deletions (Barrenäs et al., 1999). Interestingly, both recurrent acute and/or secretory otitis media (the major ear and hearing problem among children) and presbycusis (the major hearing problem among the elderly) occur more frequently in men (46,XY) than in women (46,XX) (Stenström and Ingvarsson, 1994, Jönsson et al., 1998).
The main objective of this study was to correlate ear and hearing dysfunctions in TS with the degree of mosaicism of 45,X cells. It has recently been suggested that all TS subjects are mosaicism cases (Fernandez et al., 1996, Leonova and Hanson, 1999). Since short stature is a main clinical finding in TS, an additional aim was to investigate the association between growth and hearing. The aim was also to present a hypothesis explaining why short stature and ear and hearing problems are often combined in chromosomal disorders.
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Subjects
This study comprises 119 girls and women with TS from western Sweden (age range: 4–73 years), who participated in a national multidisciplinary research programme, aimed at establishing an optimum treatment and overall care recommendations for individuals with TS in Sweden. The subjects were recruited from the Turner Syndrome Society by an advertisement in the society’s newsletter and by referral from the hospitals. The subjects were examined by different specialists. The occurrence of auricular
Results
Descriptive audiologic data regarding ear problems, hearing function and chromosomal aberration according to degree of mosaicism (severe or moderate/slight) are presented in Table 1. The degree of mosaicism varied between 2 and 100% (median=96%). Among the severe cases (proportion of 45,X cells≥96%), auricular anomalies (such as low-set auricles, narrowing of the external auditory canal, cupped auricles and abnormally protruding ears), occurred somewhat more frequently and hearing loss was
Discussion
This study showed that ear and hearing disorders in TS were related to genotype, serum concentrations of IGF-1 and height. The more severe the sensorineural hearing loss or the higher the prevalence of auricular anomalies, the higher the proportion of 45,X cells, i.e. the more severe the degree of mosaicism. Furthermore, with increasing age the proportion of 45,X cells in the buccal mucosa declined. Moreover, both middle ear infections and sensorineural hearing loss were related to low IGF-1
Acknowledgments
We thank Professors Lars Wilhelmsen, Kerstin Albertsson-Wikland, P.O. Jansson, Olle Isaksson, Inger Bryman and K.M. Holgers for fruitful discussions. The study was supported by grants from the Hjalmar Svensson Foundation and The Swedish Medical Research Council (11606).
References (44)
- et al.
The influence of karyotype on the auricle, otitis media and hearing in Turner syndrome
Hear. Res.
(1999) - et al.
Turner’s syndrome and hearing disorders in women aged 16–34
Hear. Res.
(1997) - et al.
Ear and hearing problems in 44 middle-aged women with Turner’s syndrome
Hear. Res.
(1994) - et al.
The embryonic development of sensory organs and the skull in the trisomy 16 mouse, an animal model for Down’s syndrome
Anat. Anz.
(1997) - et al.
General illness and need of medical care in otitis media prone children
Int. J. Pediatr. Otorhinolaryngol.
(1994) - et al.
Eustachian tube function in otitis-prone and healthy children
Int. J. Pediatr. Otorhinolaryngol.
(1991) - et al.
The development of the vertebrate inner ear
Mech. Dev.
(1998) - et al.
Adjusting the risk for trisomy 21 on the basis of second-trimester ultrasonography
Am. J. Obstet. Gynecol.
(1995) - Aitkin, M., Anderson, D., Francis, B., Hinde, J., 1990. Statistical Modelling in GLIM. Clarendon Press, Oxford, pp....
- et al.
Hearing impairment in Turner’s syndrome
Acta Otolaryngol. (Stockh.)
(1969)