Proximal symphalangism, hyperopia, conductive hearing impairment, and the NOG gene: 2 new mutations.

OBJECTIVES

To report on 2 families with proximal symphalangism syndrome and 2 new NOG gene mutations and to report on the outcomes of exploratory tympanotomy.

STUDY DESIGN

Retrospective chart study.

SETTING

Tertiary referral center.

PATIENTS

A total of 6 patients, one of which underwent an exploratory tympanotomy, were examined from 2 families.

INTERVENTION

Exploratory tympanotomy in 1 patient.

MAIN OUTCOME MEASURES

Medical and otologic histories and postoperative hearing outcomes.

RESULTS

In the patient that was operated upon, the preoperative air conduction hearing threshold of 55 dB was reduced to 41 dB with a residual air bone gap of 21 dB. Furthermore, deoxyribonucleic acid analysis revealed 2 different mutations: a heterozygous nonsense mutation in the NOG gene, c.391C>T (p.Gln131X), and a frameshift mutation in the NOG gene (NOG, c.304del (p.Ala102fs)).

CONCLUSION

NOG gene mutations, which lead to aberrant noggin protein function, give rise to a large spectrum of clinical findings and different symphalangism syndromes. These syndromes are all allelic disorders within the Noggin phenotype spectrum. We report on 2 new mutations that are supplementary to those previously described in the literature.