A novel ARNSHI (autosomal recessive non-syndromic hearing impairment) locus, DFNB71, was localized to 8p22-21.3. To map the locus, a whole-genome scan was carried out using DNA samples from a consanguineous seven-generational Pakistani family with profound prelingual ARNSHI. A maximum multipoint LOD score of 4.2 occurred at marker D8S261. The DFNB71 region of homozygosity and 3-unit support interval is flanked by markers D8S1130 and D8S1786. This region has a genetic distance of 19.1 cM and contains 10.6 Mb of sequence.

LHFPL5, the gene for DFNB67, underlies autosomal recessive nonsyndromic hearing impairment. We identified seven Pakistani families that mapped to 6p21.31, which includes the LHFPL5 gene. Sanger sequencing of LHFPL5 using DNA samples from hearing impaired and unaffected members of these seven families identified four variants. Among the identified variants, two were novel: one missense c.452 G > T (p.Gly151Val) and one splice site variant (c.*16 + 1 G > A) were each identified in two families. Two known variants: c.250delC (p.Leu84*) and c.380 A > G (p.Tyr127Cys) were also observed in two families and a single family, respectively. Nucleotides c.452G and c.*16 + 1G and amino-acid residue p.Gly151 are under strong evolutionary conservation. In silico bioinformatics analyses predicted these variants to be damaging. The splice site variant (c.*16 + 1 G > A) is predicted to affect pre-mRNA splicing and a loss of the 5' donor splice site in the 3'-untranslated region (3'-UTR). Further analysis supports the activation of a cryptic splice site approximately 357-bp downstream, leading to an extended 3'-UTR with additional regulatory motifs. In conclusion, we identified two novel variants in LHFPL5, including a unique 3'-UTR splice site variant that is predicted to impact pre-mRNA splicing and regulation through an extended 3'-UTR.

A novel locus for autosomal recessive nonsyndromic hearing impairment (ARNSHI), DFNB96, was mapped to the 1p36.31-p36.13 region. A whole-genome linkage scan was performed using DNA samples from a consanguineous family from Pakistan with ARNSHI. A maximum two-point logarithm of odds (LOD) score of 3.2 was obtained at marker rs8627 (chromosome 1: 8.34 Mb) at θ=0 and a significant maximum multipoint LOD score of 3.8 was achieved at 15 contiguous markers from rs630075 (9.3 Mb) to rs10927583 (15.13 Mb). The 3-unit support interval and the region of homozygosity were both delimited by markers rs3817914 (6.42 Mb) and rs477558 (18.09 Mb) and contained 11.67 Mb. Of the 125 genes within the DFNB96 interval, the previously identified ARNSHI gene for DFNB36, ESPN, and two genes that cause Bartter syndrome, CLCNKA and CLCNKB, were sequenced, but no potentially causal variants were identified.

Wolfram syndrome (WFS) is characterized by deafness, diabetes mellitus, and diabetes insipidus along with optic atrophy. WFS has an autosomal recessive mode of inheritance and is due to variants in WFS1 and CISD2.