Nance-Horan syndrome (NHS) is an X-linked disorder characterized by congenital cataracts, dental anomalies, dysmorphic features, and, in some cases, mental retardation. NHS has been mapped to a 1.3-Mb interval on Xp22.13. We have confirmed the same localization in the original, extended Australian family with NHS and have identified protein-truncating mutations in a novel gene, which we have called "NHS," in five families. The NHS gene encompasses approximately 650 kb of genomic DNA, coding for a 1,630-amino acid putative nuclear protein. NHS orthologs were found in other vertebrates, but no sequence similarity to known genes was identified. The murine developmental expression profile of the NHS gene was studied using in situ hybridization and a mouse line containing a lacZ reporter-gene insertion in the Nhs locus. We found a complex pattern of temporally and spatially regulated expression, which, together with the pleiotropic features of NHS, suggests that this gene has key functions in the regulation of eye, tooth, brain, and craniofacial development.
Orbital myositis implies orbital inflammation confined to one or more of the extraocular muscles. Orbital computerised tomography (CT) demonstrates irregular extraocular muscle enlargement which extends anteriorly to involve the tendon (muscle insertion). Six cases of presumed orbital myositis are reported, in each of whom the diagnosis was suspected clinically and confirmed by the orbital CT scan appearances. The mean age of the patients was 33 years (range 8-45 years). All presented with painful ophthalmoplegia and the majority manifested proptosis (five cases), conjunctival congestion (five cases) and periorbital and eyelid edema (two cases). Systemic corticosteroid therapy was used in two patients initially and also in another patient who relapsed, with rapid and dramatic responses. Extraocular muscle biopsy was performed in one case, disclosing features of non-specific muscle inflammation and no evidence of vasculitis. It is considered that orbital myositis is a discrete, identifiable subgroup within the spectrum of the nonspecific idiopathic orbital inflammatory syndromes; termed previously orbital 'pseudotumours'. Although the clinical features are frequently suggestive, they are nonspecific, and non-invasive investigations such as orbital ultra-sonography and CT scanning are required for precise anatomical tissue localisation and diagnosis. The role of ocular muscle biopsy is probably limited to atypical cases, or those unresponsive to steroid therapy, particularly to exclude neoplasia. Orbital myositis may be acute, subacute or recurrent. The acute form responds well to high doses of oral corticosteroids tapered gradually, but it may recur or become chronic. The subacute form of the disease responds less well.
The osteopetroses are a heterogeneous group of disorders characterised by generalised bony sclerosis. The autosomal dominant form usually has a “benign” prognosis, in contrast to the “malignant” course of the autosomal recessive variety. In this paper we describe a kindred in which the phenotypic spectrum varied from an asymptomatic condition in adults to a severely affected infant, presenting with anaemia, hepatosplenomegaly, hydrocephalus and blindness. The findings in this family are reported and discussed to elucidate further the possible genetic heterogeneity in autosomal dominant osteopetrosis.
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