Repeated transmission of X-linked ocular albinism type 1 by a carrier oocyte donor

Constitutive RB1 mutation in a child conceived by in vitro fertilization: implications for genetic counseling

Background

The purpose of this study was to identify mutations associated with bilateral retinoblastoma in a quadruplet conceived by in vitro fertilization, and to trace the parental origin of mutations in the four quadruplets and their father.

Methods

Mutational screening was carried out by sequencing. Genotyping was carried out for determining quadruplet zygosity.

Results

The proband was a carrier of a novel RB1 constitutive mutation (g.2056C>G) which was not detected in her father or her unaffected sisters, and of two other mutations (g.39606 C>T and g.174351T>A) also present in two monozygotic sisters. The novel mutation probably occurred de novo while the others were of likely maternal origin. The novel mutation, affecting the Kozak consensus at the 5'UTR of RB1 and g.174351T>A were likely associated to retinoblastoma in the proband.

Conclusion

Molecular diagnosis of retinoblastoma requires genotypic data of the family for determining hereditary transmission. In the case of children generated by IVF with oocytes from an anonymous donor which had been stored in a cell repository, this might not be successfully accomplished, making precise diagnosis impracticable for genetic counseling.

Multiple transmissions of Barth syndrome through an oocyte donor with a de novo TAZ mutation

OBJECTIVE

To report recurrent transmissions of Barth syndrome through a single oocyte donor carrying a de novo TAZ mutation.

DESIGN

Case report.

SETTING

Clinical molecular diagnostics laboratory.

PATIENT(S)

Oocyte donor and individuals conceived with her oocytes.

INTERVENTION(S)

Molecular testing.

MAIN OUTCOME MEASURE(S)

Detection of TAZ mutation.

RESULT(S)

Multiple individuals affected with Barth syndrome conceived from a single oocyte donor who is a carrier of a de novo TAZ mutation.

CONCLUSION(S)

We report multiple transmissions of Barth syndrome through a single oocyte donor with a de novo TAZ mutation.

New insights into ocular albinism type 1 (OA1): Mutations and polymorphisms of the OA1 gene

Albinism ocular type 1 (OA1) is an X-linked type of albinism that mainly effects pigment production in the eye, resulting in hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers, and reduced visual acuity. The OA1 gene is located on chromosome Xp22.32 and the coding sequence is divided into nine exons. The protein is an integral transmembrane protein that has weak similarities to G protein-coupled receptors. A total of 25 missense, two nonsense, nine frameshift, and five splicing mutations have been reported in the OA1 gene associated with OA1. There are also several deletions of some or all exons of the OA1 gene with deletions of exon 2 resulting from unequal crossing-over, due to flanking Alu repeats. Mutation and polymorphism data on this gene is available from the International Albinism Center - Albinism Database web site (http://www.cbc.umn.edu/tad).