ATP7B mutations in families in a predominantly Southern Indian cohort of Wilson's disease patients.

Objective: To analyze ATP7B mutations in Wilson's disease (WD) patients from the Indian subcontinent and to correlate these with WD phenotype.
Methods: We studied 27 WD patients from 25 unrelated families. Twenty-two families were from three southern Indian states - Tamil Nadu andhra Pradesh and Kerala. We applied conformation- sensitive gel electrophoresis (CSGE) to screen for the mutations in patients and their families. PCR products exhibiting aberrant patterns in CSGE were subjected to direct DNA sequencing. As siblings affected by WD within a family share identical ATP7B genotype, we compared WD phenotype among affected siblings within families.
Results: ATP7B mutations were detected in 22 of the 25 probands -13 were homozygotes and 9 were compound heterozygotes. Eleven novel mutations were detected. Only two common mutations were found: G3182A in 4 (16%) and C813A in 3 (12%) probands. 'Hot spots' for ATP7B mutations were exons 18 and 13. Lack of common dominant mutations prevented correlation of individual ATP7B mutations with WD phenotype. Symptomatic WD in a live sibling was not found in any family. In 8 families, a sibling died of presumed WD - in 6 of these, WD phenotype was identical to that in the proband.
Conclusions: We describe the spectrum of ATP7B mutations including 11 novel mutations in Indian WD patients and document lack of a single dominant mutation. Identical WD phenotype among siblings in only 6 of 8 families with >1 child affected by WD suggests that factors other than ATP7B mutations influence WD phenotype.