Ocular pathology in disialotransferrin developmental deficiency syndrome

Macular hypoplasia in congenital disorder of glycosylation type ia

Congenital disorders of glycosylation are a rare group of metabolic disorders that can result in multiorgan disease. This article describes a novel finding of macular hypoplasia in congenital disorders of glycosylation type Ia.

The clinical spectrum of phosphomannomutase 2 deficiency (CDG-Ia)

Congenital disorders of glycosylation are a clinically and genetically heterogeneous group of disorders resulting from abnormal glycosylation of various glycoconjugates. The first description of congenital disorders of glycosylation was published in the early 80s and once screening tests for glycosylation disorders (CDGs) became readily available, CDG-Ia became the most frequently diagnosed CDG subtype. CDG-Ia is pan-ethnic and the spectrum of the clinical manifestations is still evolving: it spans from severe hydrops fetalis and fetal loss to a (nearly) normal phenotype. However, the most common presentation in infancy is of a multisystem disorder with central nervous system involvement.

Developments in molecular genetics and electrophysiology in inherited retinal disorders

Retinitis pigmentosa is said to be the most frequent reason for severe visual handicap among young people in Scandinavia today. Developments in the fields of electrophysiology and molecular genetics have increased our understanding of the pathophysiology of these disorders and have also improved our clinical competence, leading to a better understanding of the patient's visual handicap and his or her prognosis. This represents the first step towards fulfilling our plan for the future, which is ultimately to cure blindness caused by the different forms of hereditary retinal degeneration. This review is based on 20 years of research at the Department of Ophthalmology in Lund.

Congenital disorders of glycosylation: review of their molecular bases, clinical presentations and specific therapies

Congenital disorders of glycosylation (CDG, formerly named carbohydrate-deficient glycoprotein syndromes) are a rapidly growing family of inherited disorders affecting the assembly or processing of glycans on glycoconjugates. The clinical spectrum of the different types of CDG discovered so far is variable, ranging from severe multisystemic disorders to disorders restricted to specific organs. This review deals with clinical, diagnostic, and biochemical aspects of all characterized CDGs, including a disorder affecting the N-glycosylation of erythrocytes, congenital dyserythropoietic anemia type II (CDA II/HEMPAS), and the first disorders affecting O-glycosylation. Since the clinical spectrum of symptoms in CDG is variable and may be unspecific, a generous selective screening for the presence of CDG is recommended.

Evolution of ophthalmic and electrophysiological findings in identical twin sisters with the carbohydrate deficient glycoprotein syndrome type 1 over a period of 14 years

AIMS

To evaluate the evolution of ocular and electroretinographic findings in identical twin sisters with the carbohydrate deficient glycoprotein (CDG) syndrome over a period of 14 years.

METHODS

Both girls underwent a clinical ophthalmic examination with funduscopy and an electrophysiological assessment with recording of flash electroretinogram (FERG) at the age of 4 years and 18 years

RESULTS

On ophthalmic examination at the age of 4 years an alternating convergent squint and a saccadic pursuit was diagnosed. In both, vision was 6/9 bilaterally. Fundus examination showed normal optic discs, narrow blood vessels, and a mild irregular pigmentation in the periphery. In one girl the FERG showed a recognisable a, b1, and b2-wave with reduced amplitude to less than 40% of the normal. In the other girl the reduction in amplitude was still more obvious, but for the white flash a small b1-wave was still present. At the age of 18 vision had remained 6/9 in both eyes. Funduscopy showed pink optic discs, moderately narrowed blood vessels, and bony spicule pigmentary deposits in the mid periphery. The adapto ERG, performed in identical conditions at 18 years of age, showed a completely extinguished trace for both eyes.

CONCLUSIONS

Despite progressive deterioration of ERG findings good central vision was preserved over 14 years.

Carbohydrate deficient glycoprotein syndrome type I: ophthalmic aspects in four Sicilian patients

Four patients with carbohydrate deficient glycoprotein (CDG) syndrome type I underwent ophthalmic examination. All of them had retinitis pigmentosa with extinguished scotopic electroretinogram. The importance of CDG syndromes as one of the metabolic causes of retinal dystrophy with 'bony spicule' pigment is stressed.

Carbohydrate-deficient glycoprotein syndromes: peculiar group of new disorders

A new group of metabolic disorders, the carbohydrate-deficient glycoprotein (CDG) syndromes, is reviewed with emphasis on the key condition, the CDG syndrome type I. This disease, an autosomal-recessive multisystem condition, has now been diagnosed in 45 Scandinavian patients. It is characterized by carbohydrate deficiencies of a number of glycoproteins, including uniform changes in transferrin. The transferrin alterations provide a distinct biologic marker and a practical and simple laboratory diagnostic means employing analysis of serum or blood spots from Guthrie-type filter paper. The syndrome presents differently through various life periods. A four-stage grouping system by age has been constructed and is presented. During infancy, internal organ symptoms are dominant; some may be life-threatening. In later childhood and adolescence, static mental deficiency, cerebellar ataxia, slowly progressive lower limb neuropathy, and pigmentary retinal degeneration, as well as secondary skeletal deformities, are the most prominent findings. Two very recently described clinical and biologic variants, CDG syndromes II and III, are summarized and compared to CDG type I.

Full-field electroretinograms in patients with the carbohydrate-deficient glycoprotein syndrome

We examined five patients who had carbohydrate-deficient glycoprotein syndrome with full-field electroretinograms. Only two of the patients showed fundus changes typical for retinitis pigmentosa, whereas abnormal electroretinograms were seen in all patients. There was no recordable rod response; however, a delay in the cone b-wave implicit time was noted. All patients had nyctalopia. These observations suggest that patients with the carbohydrate-deficient glycoprotein syndrome have a progressive tapetoretinal degenerative disorder of the retinitis pigmentosa type with defined alterations in the electroretinogram.