Clinical and morphological features of Waardenburg syndrome type II

Abstract

Evaluation of 4-month-old girl who presented with congenital cataracts revealed heterochromia iridis, fundus hypopigmentation, residual white forelock and sensory neural hearing loss--findings consistent with Waardenburg syndrome type II. Bilateral peripheral iridectomies performed at lensectomy provided tissue for evaluation. Light microscopy revealed fewer melanocytes in the blue iris than in the brown. Electron microscopic examination showed a significant (p = 0.0001) reduction in melanosome size in the blue iris, and the nerve endings contained fewer vesicles. A defect in neural crest cell migration and melanin synthesis may be responsible for the heterochromia iridis seen in Waardenburg syndrome type II.

Distant regulatory elements in a Sox10‐βGEO BAC transgene are required for expression of Sox10 in the enteric nervous system and other neural crest‐derived tissues

“…Both the thymus and the C-cells of the thyroid have been established as being of neural crest origin (Pearse and Polak, 1971;Kuratani and Bockman, 1990). Nerve fibers were visible migrating into the iris of the E14.5 eye, consistent with reduced pupillary responses of HSCR patients to light and literature reports of reduced nerve endings and altered melanosomes in heterochromia iridis in some individuals (Mullaney et al, 1998). No Sox10␤ GeoBAC expression was observed in embryonic liver or splenic tissue (data not shown).…”

Don’t it make my blue eyes brown: heterochromia and other abnormalities of the iris

“…40 Histopathological studies of the irides of patients with Waardenburg syndrome are limited. Mullaney et al 46 described the light and electron microscopic findings of the irides in a patient with the type-II variant of Waardenburg syndrome. They found a reduction in the number of stromal melanocytes in deep blue iris when compared with the fellow brown eye.…”

“…Furthermore, the melanosomes were smaller and fewer in number in the blue iris when compared with the brown iris. 46 Iris freckles. Iris freckles are flat, discrete areas of brown pigmentation on the iris surface.…”

„Auditory pigmentary syndromes“ — klinische Erscheinungsbilder und genetischer Hintergrund

“…This family provides additional evidence for the importance of exact observation of the clinical phenotype as a step to shed light on the underlying mechanisms at the molecular level. [12,14].…”

“…Das kombinierte Auftreten von Pigmentstörungen des Auges, der Haare und der Haut mit kongenitaler Innenohr -s c h w e r h ö r i g k e i t ist ein biologisches Phänomen, das nicht nur bei Katzen, Hunden und tanzenden Mäusen [2,14,9] beschrieben wurde, sondern auch beim Menschen. In der vor -g e s t e l l t e n türkischen Familie, in der 2 von 3 Söhnen die klas -s i s c h e n Symptome eines WS Typ 2 zeigten, hatten wir die Gelegenheit einige interessante Beobachtungen bezüglich der Pathophysiologie dieses klinisch wie genetisch sehr heterogenen Krankheitsbildes zu machen.…”