DNA-based prenatal diagnosis in a Chinese family with xeroderma pigmentosum group A.

BACKGROUND

Xeroderma pigmentosum (XP) is a group of autosomal recessive diseases characterized by hypersensitivity to ultraviolet rays. Among its eight complementation groups, XP group A (XPA) is the most severe type. The XPAC gene has been identified as the defective gene in XPA patients.

OBJECTIVES

To examine genomic DNA from a Chinese family with XPA, to determine the XPAC mutation and, after genetic counselling, to undertake DNA-based prenatal diagnosis in a subsequent pregnancy.

METHODS

Fetal DNA was extracted from amniotic fluid and used to amplify exon 5 of XPAC containing the potential mutation. Direct sequencing and restriction endonuclease digestion were used for prenatal diagnosis.

RESULTS

We identified a homozygous nonsense XPAC mutation of 631C-->T, which results in an R211X mutation in XPA protein, in the proband. Both her parents are heterozygous. Prenatal diagnosis demonstrated a heterozygous sequence predicting an unaffected child, and a healthy girl was born.

CONCLUSIONS

These data provide the first example of a DNA-based prenatal test for genodermatosis in China.