Figure 2.

Identification of Nonsense Mutations in SMPX

(A) Sequencing of genomic DNA revealed the SMPX nonsense mutations c.109G>T in exon 3 in the German family (left) and c.175G>T in exon 4 in the Spanish family¹⁴ (right). Electropherograms of a respective heterozygous female carrier and a hemizygous male are shown in comparison to a reference sequence. No additional mutations have been identified in a cohort of 34 GJB2-negative individuals with early-onset hearing loss.

(B) SMPX is composed of five exons (left, the coding sequence is given in blue) and encodes an 88 amino acid protein (right) without known functional domains.