© Borgis - New Medicine 3/1999, s. 46-47
Teresa Oleniacz1, Hanna Dmeńska2
Upper and lower chronic respiratory tract infections in patients with retinitis pigmentosa (RP)
1 Audiology, Phoniatry and Laryngology Dept.
Head: Barbara Bułat, M.D.
2 Lung Physiology Dept. of The Memorial Institute of Child Health Centre, Warsaw
Head: Prof. Piotr Gutkowski, M.D.
Retinitis pigmentosa (RP) is a term for a heterogeneous group of hereditary retinal disorders characterised by progressive night blindness, loss of peripheral visual field and often by complete functional blindness by 40 to 50 years of age. Photoreceptor ultrastuctural studies of retinas in RP patients suggest that a defect of the connecting cilium of rods and cones could lead to the degeneration of these cells. It has been suggested that in RP patients motile cilia are also structurally defective. In this paper the cases of three brothers with X chromosome-linked RP and chronic upper and lower respiratory tract infections due to motile cilia structure disorders are presented.
RP defines a clinically and genetically heterogeneous group of congenital retinal diseases characterised by progressive photoreceptor and pigmentary retina epithelium degeneration. RP symptoms are night blindness, accommodation disorders, loss of the peripheral visual field, reduction of visual sharpness and even complete blindness by 4050 years of age. The disorders are always bilateral and of a progressive character. Ophthalmology examination shows the visual field reduced to 10°, reduction in visual sharpness, characteristic pigmentary changes on the eyeground, and electroretinography changes (lack or essential reduction of scotop and photop retinal response).
RP is inherited autosomally - in arecessive or dominant way or Xchromosome linked. Its incidence depends on the ethnic group and is 1:3500 to 1:4000. RP might be observed as an isolated form or as an element of syndromes including Usher, Laurence-Moon-Biedl, and Cockayene.
Photoreceptor ultrastructure studies in RP patients show that the basis of retinal degeneration is a disorder of the rods and cones connecting cilium (2, 6). The cilium connects the external segment containing the photosensitive pigment and the internal segment with cell organelles. The cilium structure is similar to the basal part of motile cilia; it is composed of nine microtubular doublets without central microtubules. There is also a lack of dynein arms and radial spokes (2). There is evidence that in RP cases there are ultrastructure disorders of both respiratory cilia and spermatozoon axoneme (1, 5, 7). Genetic studies show that RP depends on mutations of at least 7 genes; four of them are responsible for phototransduction protein cascade, two for the structure proteins of the external photoreceptor segment, and one for myosin VII formation (the deficit is observed in Usher´s syndrome type I). X-linked RP is clinically the most severe form and its incidence is 6 - 22% of all RP patients.
On the X chromosome are two specific loci for RP: RP2 located in the Xp 11.2 - p11.4 region and RP3 in the Xp 11.4 - p21.1 region. The loci are recessively expressed (4, 9). Recent publications describe new X chromosome RP loci expressed dominantly (7).
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