Genetic tests reveal evidence of differences relevant to facioscapulohumeral muscular dystrophy diagnostics. Credit: TEK IMAGE/SPL/GETTY IMAGES
Researchers have deciphered the genetic profile of Indians with facioscapulohumeral muscular dystrophy (FSHD), a rare genetic muscle disease. This could help prevent misdiagnosis1.
FSHD affects the face, shoulders and upper arms, and is challenging to differentiate from other conditions. The disease is caused by an abnormal expression of transcription factor DUX4, a gene embedded in the D4Z4 microsatellite repeat array (or repetitive DNA), on chromosome 4.
People without the disease have a D4Z4 array with 8 to 100 contiguous units (8-100U), but in people with FSHD 1, the most common form of FSHD, this repeat is shortened to one to 10 units (1-10U).
A multi-country research team, led by the All India Institute of Medical Sciences (AIIMS) in New Delhi, tested 91 families from north India, totalling 235 individuals, showing FSHD symptoms. The researchers used Southern blotting, PCR analysis and optical genome mapping to analyze the participants’ genetic features.
The team identified FSHD1 1-9U allele in nearly 60% of the families. Of these, four contained an 8-10U FSHD1 allele (7%) compared with more than 17% of European FSHD1 patients, which suggests people with European genetic ancestry who have this allele size are more susceptible to FSHD than those from India.
The results also show that compared with Europeans more people in India carry disease-causing shortened repeat DNA sequences — 4 unit and 5 unit FSHD1 alleles — but are asymptomatic.
The findings highlight the need for inclusivity in genetic studies to develop effective treatments.
