Phenotypic manifestations associated with CAG-repeat expansion in the androgen receptor gene in male patients and heterozygous females: a clinical and molecular study of 30 families

Spinal and bulbar muscular atrophy (Kennedy disease) is an adult form of X-linked motor neuron disease caused by the expansion of a polymorphic CAG-repeat sequence in the first exon of the androgen receptor gene. We studied clinical and molecular features of 36 patients and 19 heterozygous females. Phenotypic manifestations and disease severity broadly varied among our spinal and bulbar muscular atrophy patients. The size of CAG expansion significantly influences the age of disease onset, but neither clinical features nor disease severity. The majority of carrier women presented signs of chronic denervation at neurophysiological examination and, in three cases, low-amplitude sensory action potentials were recorded. Notably, a few women developed mild signs of bulbar motor neuron impairment later in life. The identification of a large number of patients by the use of the molecular test further supports the hypothesis that Kennedy disease had been previously underdiagnosed, probably because of the great variability of clinical presentation. Although an early diagnosis may not be crucial for treatment, given the lack of effective therapy, the molecular testing can be of great relevance for disease prognosis and genetic counseling.

Multiple abnormalities of ectoglycosyltransferases in cultured fibroblasts from patients with mucolipidosis II: Possible indication for abnormal plasma membrane glycoproteins

Ectoglycosyltransferase activities were measured in cultured normal and mucolipidosis II fibroblasts using endogenous glycoproteins and glycolipids and whole cells. Nucleotide pyrophosphatase, known to interfere with glycosyltransferases, was completely inhibited with 6 mM 5' AMP. Since preliminary experiments have shown multiple abnormalities of ectoglycosyltransferases in mucolipidosis II fibroblasts (Di Donato, unpublished results), galactosyl (Gal)-and N-acetylglucosaminyl (GluNac)-transferase were studied in further detail in confluent and nonconfluent cultures of normal and patient fibroblasts. Activities of both transferases on glycoproteins were higher in nonconfluent cultures. A 50% reduced activity of Gal-transferase was measured in confluent mucolipidosis II cultures and of GluNac-transferase in nonconfluent mucolipidosis II cultures towards incorporation of sugar precursors into glycoproteins. Substrate saturation kinetics of both transferases in mucolipidosis II fibroblasts revealed an abnormal Km for Gal incorporation into endogenous glycoproteins. Glycosylation of glycolipids in mucolipidosis fibroblasts was normal.