Foredragsholder / Presenter

Navn / Name:                      Cecilie Bredrup

Institution:                           Haukeland Universitetssykehus/Great Ormond Street Hospital for Children

Afdeling / Department:        Department of Ophthalmology

E-mail:                                cecilie.bredrup@helse-bergen.no

Medforfattere / Co-authors:

Navn / Name:                      Isabelle Russell-Eggitt                                                   

Institution:                           Great Ormond Street Hospital for Children

Afdeling / Department:        Department of Ophthalmology

Navn / Name:                      Raoul C. Hennekam

Institution:                            Great Ormond Street Hospital

Afdeling / Department:        Clinical and Molecular Genetics Unit

Navn / Name:                      Detlef Bockenhauer                                 

Institution:                           Great Ormond Street Hospital

Afdeling / Department:        Paediatric Nephrology

Navn / Name:                      Martin Zenker

Institution:                           University of Erlangen-Nuremberg

Afdeling / Department:         Institute of Human Genetics

ABSTRACT

Background:

Pierson syndrome consists of congenital nephritic syndrome and distinct ocular anomalies with microcoria as the most prominent feature. It is caused by mutations in LAMB2 leading to loss of function of the gene. The patients are typically diagnosed shortly after birth and succumb due to their renal failure. However, patients with residual laminin b 2 function may display variable phenotypes and ocular problems may even precede the renal.

Aim:

To describe a patient referred due to extreme microcoria and later diagnosed with Pierson syndrome. To review LAMB2 associated ocular anomalies and to heighten ophthalmologist’s awareness of this condition.

Results:

The patient had bilateral microcoria noted shortly after birth. He appeared otherwise healthy. Further examination revealed a flat iris, embryotoxon posterior, cataract, abnormal lens shape and retinal atrophy. A PubMed search with the words microcoria gave Pierson syndrome as a differential diagnosis. Renal ultrasound and sequencing of the LAMB2 gene confirmed the diagnosis. A homozygous mutation in exon 7 (c.736C>T) was found, probably associated with some residual function.

In the literature we found 29 patients from 10 pedigrees with mutations in LAMB2. The ocular phenotype varied considerably from described as normal in one instance, to unspecific ocular anomalies, progressive visual loss due to retinal detachment and to a more global maldevelopment similar to what was seen in our patient. In several instances the ophthalmoic symptoms preceded the renal.

Conclusion:

Mutations leading to loss of function of LAMB2 expression cause a wide range of ocular anomalies. Although Pierson syndrome usually presents with renal failure and microcoria shortly after birth, variable phenotypes occur. In babies presenting with microcoria, renal function should be examined even if they appear healthy.