Analysis of CAG repeat expansion in Huntington's disease gene (IT 15) in a Hungarian population

Genetic epidemiological characteristics of a Hungarian subpopulation of patients with Huntington's disease

Background

Recent advances in therapeutic options may prevent deterioration related to Huntington’s disease (HD), even at the pre-symptomatic stage. Be that as it may, a well-characterized patient population is essential for screening and monitoring outcome. Accordingly, the aim of this study was to describe the characteristics of a Hungarian subpopulation of HD patients and mutation carriers diagnosed at the University of Szeged.

Methods

We conducted a search for International Classification of Diseases (ICD) code G10H0 in the local medical database for the period of 1 January 1998 to 31 December 2018.

Results

We identified 90 HD cases (male: 45, female: 45) and 34 asymptomatic carriers (male: 15, female: 19). The median age of onset was 45 years (range: 16–79). There were 3 cases of juvenile onset (3.3%), and 7 of late disease onset (7.8%). The median repeat length was 43 (range: 36–70) for the pathological and 19 for the non-pathological alleles (range: 9–35). 17.5% of the pathological alleles were in the decreased penetrance range, while 7% of non-pathological alleles were intermediate.

Conclusions

The genetic and clinical features of the population examined in the present study were in line with the previous Hungarian study, as well as with international literature. The exceptions were the higher ratio of reduced penetrance and intermediate alleles.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02089-9.

Discrepancy in prevalence of Huntington's disease in two Swedish regions

BACKGROUND

Huntington's disease (HD) is a neurodegenerative disease with an autosomal dominant pattern of inheritance. The prevalence varies between different geographical regions with an estimated average in Europe of about 6/100 000. Parts of northern Sweden are known to have an accumulation of HD, but no prevalence studies have been undertaken for 50 years.

OBJECT

The aim of this study was to estimate the prevalence of HD in the two different Swedish counties of Jämtland and Uppsala and compare them with the reported prevalence in Europe.

METHOD

Patients registered with the diagnosis of HD were identified through medical records in each county. Presymptomatic patients were excluded. We also compared the annual number of individuals with HD registered in the database of the National Board of Health and Welfare in these regions, with all of Sweden.

RESULTS

The prevalence of HD was found to be 22.1/100 000 in Jämtland and 4.9/100 000 in Uppsala county. The mean age was 62.2 years and 61.8 years, respectively. The annual average of patients with HD registered at inpatient care was 1.5/100 000 in Jämtland, 0.44/100 000 in Uppsala county, and 0.56/100 000 in all of Sweden.

CONCLUSION

The prevalence of patients with the diagnosis of HD is four times higher in the county of Jämtland than in the county of Uppsala, where the prevalence is more similar to the average in Europe. Our results support earlier findings of regional variations of HD prevalence with an accumulation in certain parts of northern Sweden.

Somatosensory evoked potentials correlate with genetics in Huntington's disease

Abnormalities of somatosensory evoked potentials (SEPs) have been reported in Huntington's disease, a neuropsychiatric disorder caused by the expansion of a CAG trinucleotide repeat. The aim of our study was to determine the relationship between these electrophysiological changes and the length of the nucleotide repeat. We found a striking correlation between the decrease in the early component amplitudes (N20 and N30) of the median nerve SEP and the repeat length, suggesting that these SEP alterations are indeed related to the genetically determined pathological process. The cortical components of the tibial nerve SEP exhibited a dramatic alteration in the patient group and were the only SEP changes found in the group of asymptomatic carriers of the mutation, being more sensitive than the median nerve SEPs.