blepharitis

Microcephaly, Congenital Cataracts, and Psoriasiform Dermatitis

Clinical Characteristics
Ocular Features: 

Congenital cataracts are usually present.  No further description is available.  Some individuals have a chronic blepharitis.

Systemic Features: 

Small stature, microcephaly, and developmental delay are important features. The skin in early life, even in infancy, may have an psoriasiform dermatitis that waxes and wanes in some patients while others have only dry skin.  Chronic arthralgias are sometimes present leading to joint contractures especially in the lower extremities.  Skeletal maturation is delayed and there may be cognitive deficits.

Serum total cholesterol levels are generally low but triglycerides are in the normal range.  Serum levels of IgE and IgA may be elevated.  This condition results from defects in the cholesterol synthesis pathway.

Genetics

Compound heterozygosity or homozygosity of mutations in the SC4MOL gene (4q32.3) (also known as MSMO1) is responsible for this condition.  Parents with a single mutation may have mildly elevated plasma methylsterol levels.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cholesterol supplementation and the use of statins has been reported to improve symptoms.  The usual treatments for psoriasis may provide some temporary relief.  Physical therapy may prevent joint contractures.  Antibiotic drops or ointment may be helpful in the treatment of blepharitis.

References
Article Title: 

The role of sterol-C4-methyl oxidase

He M, Smith LD, Chang R, Li X, Vockley J. The role of sterol-C4-methyl oxidase
in epidermal biology. Biochim Biophys Acta. 2014 Mar;1841(3):331-5. Review.

PubMed ID: 
24144731

Dyskeratosis Congenita

Clinical Characteristics
Ocular Features: 

The conjunctiva and eyelids are prominently involved as part of the generalized mucocutaneous disease.  Keratinization of the lid margins, absent lacrimal puncta, trichiasis, cicatrizing conjunctivitis, entropion, ectropion, blepharitis, sparse eyelashes, and symblephara are important features.  The cornea is also involved with keratinization of the epithelial surface and vascularization.  The nasolacrimal duct is sometimes blocked.  At least one patient has been reported to have an exudative retinopathy. 

Systemic Features: 

Dyskeratosis congenita consists of a heterogeneous (genetic and clinical) group of inherited bone marrow failure and premature aging syndromes with the common feature of shortened telomeres.  There is considerable variability in the clinical features.  Prominent manifestations include nail dysplasia, oral leukoplakia, abnormal dentition, and reticulated skin pigmentation. Some patients have cognitive impairments.  Liver failure, testicular atrophy, pulmonary fibrosis, aplastic anemia, and osteoporosis along with features of aging such as premature grey hair and loss are typical.  There is an increased risk of malignancies, especially acute myelogenous leukemia.  Bone marrow failure is the major cause of early death.

Genetics

At least three autosomal dominant, three autosomal recessive, and one X-linked form of dyskeratosis congenita are recognized.  Mutations in at least 7 genes have been implicated.

Autosomal dominant disease can result from mutations in the TERC gene (DKCA1; 3q36.2; 127550), the TERT gene (DKCA2; 5p15.33; 613989), and the TINF2 gene (DKCA3; 14q12; 613990).  Mutations in the TINF2 gene are also responsible for Revesz syndrome (268130) with many features of DKC in addition to ocular findings of an exudative retinopathy resembling Coats disease.

Autosomal recessive disease is caused by mutations in the NOP10 (NOLA3) gene (DCKB1; 224230; 15q14-q15), the  NHP2 (NOLA2) gene (DKCB2; 5q35; 613987), and the WRAP53 gene (DKCB3; 17p13; 613988).  Mutations in the TERT gene may also cause autosomal recessive disease known as DKCB4 (613989).  

The X-linked disease (DKCX) (Zinsser-Engman-Cole syndrome) results from a mutation in the DKC1 gene (Xq28; 305000).  The same gene is mutated in Hoyeraal-Hreidarsson syndrome (300240) which some consider to be a more severe variant of dyskeratosis congenita with the added features of immunodeficiency, microcephaly, growth and mental retardation, and cerebellar hypoplasia. 

The majority of mutations occur in genes that provide instructions for making proteins involved in maintainence of telemeres located at the ends of chromosomes.  Shortened telomeres can result from maintainence deficiencies although the molecular mechanism(s) remain elusive.

Pedigree: 
Autosomal dominant
Autosomal recessive
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

Treatment for DKC with hematopoietic stem cell transplantation can be curative but its long-term efficacy is poor.  Some advocate androgen therapy first.  Lifelong cancer surveillance and frequent ocular and dental evaluations are important with specific treatment as indicated.

References
Article Title: 

Keratosis Follicularis Spinulosa Decalvans, X-Linked

Clinical Characteristics
Ocular Features: 

There is alopecia of the eyelashes and eyebrows.  The skin of the eyelids is thickened often with an associated chronic blepharitis followed by entropion (ectropion sometimes mentioned).  Photophobia and keratitis with 'corneal degeneration' are also features but it is unknown whether these are primary or secondary to trichiasis from the eyelid deformities.  The corneal findings usually precede the scarring alopecia of the scalp.

Systemic Features: 

Onset is in childhood.  Thickening of skin is generalized especially in the neck, ears, and the extremities with marked involvement of the palms and soles, especially in the calcaneal regions.  Scalp hair may be sparse, often in a streak pattern.  The follicles are inflamed and hyperkeratotic resulting in scarring alopecia.  Carriers have been reported to have dry skin with mild follicular hyperkeratosis and more extensive involvement of the soles.

Genetics

This is a rare disorder with genetic and clinical heterogeneity.  The majority of cases seem to be inherited in an X-linked recessive pattern secondary to mutations in the SAT1 gen located at Xp22.1. 

However, multigenerational families with male to male transmission have also been reported suggesting autosomal dominant inheritance (KFSD; 612843).  However, no associated mutations or loci have been reported for this condition.

 

Pedigree: 
Autosomal dominant
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

Retinoids reduce the inflammatory component and lead to cessation of the scalp alopecia.  A decrease in photophobia has also been reported but the clinical basis for this is unknown.

References
Article Title: 

Gene dosage of the spermidine/spermine N(1)-acetyltransferase ( SSAT) gene with putrescine accumulation in a patient with a Xp21.1p22.12 duplication and keratosis follicularis spinulosa decalvans (KFSD)

Gimelli G, Giglio S, Zuffardi O, Alhonen L, Suppola S, Cusano R, Lo Nigro C, Gatti R, Ravazzolo R, Seri M. Gene dosage of the spermidine/spermine N(1)-acetyltransferase ( SSAT) gene with putrescine accumulation in a patient with a Xp21.1p22.12 duplication and keratosis follicularis spinulosa decalvans (KFSD). Hum Genet. 2002 Sep;111(3):235-41.

PubMed ID: 
12215835
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