[Study on clinical manifestation, genotype and genetic characteristics of two Kennedy disease pedigrees]

To investigate the clinical manifestations, genotypes, and genetic characteristics of two pedigrees with Kennedy disease.The clinical data of the patients from two Kennedy disease families were collected. The numbers of trinucleotide CAG repeats in exon 1 of the androgen receptor gene were determined by DNA sequencing and repeat fragment analysis.Family A was composed of 58 individuals in 4 generations. The proband had onset at 39 years old. There were two Kennedy disease patients in family B which included 61 individuals in 5 generations. The two patients had onset at 39 and 41 years old, respectively. All the three patients displayed limbs and bulbar muscular weakness because of the damage of lower motor neurons. They had androgen insensitivity syndrome in common, and showed mild or moderate increase in serum creatine kinase level. The electromyogram showed wild damage in anterior horn of spinal cord. Muscle biopsy displayed neurogenic muscular atrophy. The numbers of the CAG repeat expansion in the androgen receptor gene of the three patients were 49, 48, and 47, respectively. X-linked recessive mode of inheritance was demonstrated by pedigree analysis in the two families.Kennedy disease usually occurs in mid-adulthood man. The clinical features are the weakness and wasting of limbs and bulbar muscles. Genetic analysis contributes to diagnosis and identification of carriers, and is beneficial to genetic counseling and prenatal diagnosis.