Confirmation and refinement of an autosomal dominant congenital motor nystagmus locus in chromosome 1q31.3-q32.1.

Congenital motor nystagmus (CMN) is characterized by early-onset bilateral ocular oscillations. To identify the disease locus for autosomal dominant CMN in a Chinese family 86001, clinical data, including slit lamp and funduscopic examination and blood samples were collected from family. Genomic DNA was prepared from leukocytes, and a genome-wide linkage scan was performed using 382 polymorphic microsatellite markers and two-point linkage analysis using the logarithm of odds (LOD) score method as implemented in the LINKAGE program package. Maximum two-point scores were calculated using ILINK, and LINKMAP was used for multipoint analysis. All nine affected individuals in the family showed typical phenotypes for CMN. Maximum two-point LOD scores (3.61 at θ=0) were obtained with D1S2619, D1S2877 and D1S2622.The 24.6 cM (28.07 Mb) linked region is flanked by markers D1S218 and D1S2655, placing the disease locus on chromosome 1q25.2-1q32.1. Multipoint analysis confirmed linkage to the region of D1S218 and D1S2655 with Maximum two-point scores of 3.61. The linkage interval overlaps with that of a newly reported CMN locus on 1q31-q32.2 and narrows down the linked region to 5.90 cM (5.92 Mb). This study confirms and refines a novel locus for autosomal dominant CMN to chromosome 1q31.3-q32.1 (5.90 cM) and demonstrates its presence in the Chinese population.