Two children with isolated congenital anosmia, a rare syndrome of deficient restricted neuronal migration, are presented with early diagnosis confirmed by standardized smell testing and detailed neuroimaging studies. Recognition of this disorder and its spectrum of presentations provides important insights into the molecular mechanisms underlying the development of the olfactory system.
"In a previous study that included 22 patients, 8 of them had a familial history of CGA (Leopold et al. 1992). Other sporadic cases have been described mostly in children and adolescents (Vowles et al. 1997; Assouline et al. 1998; Ho and Carrie 2001; Nishida et al. 2004). The published familial cases include a large 4-generation family with 27 affected individuals from the Faroe Islands (Lygonis 1969) and 8 American familial cases described by Leopold (Leopold et al. 1992). "
[Show abstract][Hide abstract] ABSTRACT: Anosmia affects the western world population, mostly the elderly, reaching to 5% in subjects over the age of 45 years and strongly lowering their quality of life. A smaller minority (about 0.01%) is born without a sense of smell, afflicted with congenital general anosmia (CGA). No causative genes for human CGA have been identified yet, except for some syndromic cases such as Kallman syndrome. In mice, however, deletion of any of the 3 main olfactory transduction components (guanidine triphosphate binding protein, adenylyl cyclase, and the cyclic adenosine monophosphate-gated channel) causes profound reduction of physiological responses to odorants. In an attempt to identify human CGA-related mutations, we performed whole-genome linkage analysis in affected families, but no significant linkage signals were observed, probably due to the small size of families analyzed. We further carried out direct mutation screening in the 3 main olfactory transduction genes in 64 unrelated anosmic individuals. No potentially causative mutations were identified, indicating that transduction gene variations underlie human CGA rarely and that mutations in other genes have to be identified. The screened genes were found to be under purifying selection, suggesting that they play a crucial functional role not only in olfaction but also potentially in additional pathways.
Chemical Senses 02/2007; 32(1):21-30. DOI:10.1093/chemse/bjl032 · 3.16 Impact Factor
"They tend to show between the age of 5 and 10 years. The best known genetic olfactory disorder is Kallmann's syndrome (hypogonadotropic hypogonadism with anosmia) , but isolated anosmia is also known . Neuroradiologic examination revealed marked hypoplasia or the total absence of the olfactory bulb or tract (68-84%) , in addition to clearly reduced sulcus depth . "
[Show abstract][Hide abstract] ABSTRACT: The incidence of olfactory disorders is appoximately 1-2% and they can seriously impact on the quality of life. Quantitative disorders (hyposmia, anosmia) are distinguished from qualitative disorders (parosmia, phantosmia). Olfactory disorders are classified according to the etiology and therapy is planned according to the underlying pathophysiology. In ENT patients olfactory disorders caused by sinonasal diseases are the most common ones, followed by postviral disorders. Therapy consists of topical and systemic steroids, whereas systemic application seems to be of greater value. It is very difficult to predict the improvement of olfactory function using surgery, moreover, the long term - success in surgery is questionable.
Isolated taste disorders are rare and in most often caused by underlying diseases or side effects of medications. A meticulous history is necessary and helps to choose effective treatment. In selected cases zinc might be useful.
[Show abstract][Hide abstract] ABSTRACT: Anosmias with chromosomal disorders has been well investigated. However, isolated anosmia (IA) has received less attention, although it occurs more frequently. We compared frontobasal structures in patients with IA since birth or early childhood with those in control subjects.
Imaging findings obtained in 16 patients with IA were compared with those obtained in eight control subjects. Imaging was performed with a standard quadrature head coil at 1.5 T. T1-weighted spin-echo (coronal plane perpendicular to frontal skull base; section thickness, 3 mm; pixels, 0.43 x 0.39 mm) and sagittal T1-weighted magnetization-prepared rapid gradient-echo (voxels, 1.0 x 1.0 x 1.0 mm) sequences were performed. We assessed the length and depth of the olfactory sulcus, olfactory bulb volume, and olfactory sulcus depth in the plane of the posterior tangent through the eyeballs (PPTE).
Five patients with IA had bilateral hypoplastic olfactory bulbs. Three patients with IA had hypoplastic olfactory bulbs on the right and aplastic olfactory bulbs on the left. Eight patients with IA had bilaterally aplastic olfactory bulbs. The depth of the olfactory sulcus at the level of the PPTE was smaller in patients with IA than in control subjects. The depth of the olfactory sulcus was greater on the right than on the left, and there was no overlap. Among patients with IA, the depth of the olfactory sulcus differed significantly between those with and those without visible olfactory tracts.
The depth of the olfactory sulcus at the level of the PPTE reflects the presence of olfactory tracts. The presence or absence of the olfactory tract may therefore have some association with cortical growth of the olfactory sulcus region. The olfactory sulcus is deeper on the right than on the left, particularly in patients with IA. We speculate that olfaction may be processed predominantly in the right hemisphere.
American Journal of Neuroradiology 02/2002; 23(1):157-64. · 3.59 Impact Factor
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