Cutaneous granulomas in ataxia telangiectasia and other primary immunodeficiencies: reflection of inappropriate immune regulation?

BACKGROUND: Non-infective cutaneous granulomas with unknown pathogenesis occur in various primary immunodeficiencies (PIDs) including ataxia telangiectasia (A-T). OBJECTIVE: To find a common immunological denominator in these cutaneous granulomas. METHODS: The dermatological and immunological features of 4 patients with A-T and cutaneous granulomas were described. The literature on skin granulomas in A-T and in other PIDs is reviewed. RESULTS: All 4 A-T patients had progressive granulomas on their limbs and showed decreased IgG and IgA concentrations with normal IgM levels. They had a marked decrease in B cells and naïve T cells coinciding with the appearance of the cutaneous granulomas. Similar B- and T-cell abnormalities were described in patients with other PIDs with skin granulomas. CONCLUSIONS: We hypothesize that the pathogenesis of these skin granulomas is related to immune dysregulation of macrophages due to the absence of naïve T cells with an appropriate T-cell receptor repertoire and the unopposed activity of γδ T cells and/or natural killer cells.

Clinical spectrum of ataxia-telangiectasia in adulthood.

OBJECTIVE: To describe the phenotype of adult patients with variant and classic ataxia-telangiectasia (A-T), to raise the degree of clinical suspicion for the diagnosis variant A-T, and to assess a genotype-phenotype relationship for mutations in the ATM gene. METHODS: Retrospective analysis of the clinical characteristics and course of disease in 13 adult patients with variant A-T of 9 families and 6 unrelated adults with classic A-T and mutation analysis of the ATM gene and measurements of ATM protein expression and kinase activity. RESULTS: Patients with variant A-T were only correctly diagnosed in adulthood. They often presented with extrapyramidal symptoms in childhood, whereas cerebellar ataxia appeared later. Four patients with variant A-T developed a malignancy. Patients with classic and variant A-T had elevated serum alpha-fetoprotein levels and chromosome 7/14 rearrangements. The mildest variant A-T phenotype was associated with missense mutations in the ATM gene that resulted in expression of some residual ATM protein with kinase activity. Two splicing mutations, c.331 + 5G>A and c.496 + 5G>A, caused a more severe variant A-T phenotype. The splicing mutation c.331 + 5G>A resulted in less ATM protein and kinase activity than the missense mutations. CONCLUSIONS: Ataxia-telangiectasia (A-T) should be considered in patients with unexplained extrapyramidal symptoms. Early diagnosis is important given the increased risk of malignancies and the higher risk for side effects of subsequent cancer treatment. Measurement of serum alpha-fetoprotein and chromosomal instability precipitates the correct diagnosis. There is a clear genotype-phenotype relation for A-T, since the severity of the phenotype depends on the amount of residual kinase activity as determined by the genotype.

Neuromuscular abnormalities in ataxia telangiectasia: a clinical, electrophysiological and muscle ultrasound study.

Thirteen classical ataxia telangiectasia (A-T) patients, varying in age from 1 to 25 years, were studied clinically, electrophysiologically as well as by muscle ultrasound to chart the development and spectrum of neuromuscular abnormalities in A-T. The most prominent finding was a progressive axonal sensorimotor polyneuropathy, apparent by electromyography and muscle ultrasound from the age of 8 years and becoming clinically discernible around 12 years of age. Before the age of 8 years decreased tendon reflexes and slightly slowed sensory nerve conduction velocities could already be observed. With routine electrophysiological techniques the severe polyneuropathy precludes conclusions about the presence of anterior horn cell loss in older patients.