Russia expanded the list of rare orphan diseases for the fourth time in 2026
Published 07 September 2026
Last update 10 September 2026
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On 31 August, the Russian Ministry of Health updated the list of rare orphan diseases, adding chromosome 15q11.2–q13.1 duplication syndrome (Dup15q).
The list now contains 305 entries.
How the List Expanded in 2026
In 2026, the list of rare diseases was expanded several times.
In March, it was supplemented with congenital dyskeratosis, neurodevelopmental disorder associated with the HNRNPH2 gene, chronic hypoparathyroidism, and uveal melanoma. Subsequently, chronic hypoparathyroidism was removed.
In June, desmoid-type fibromatosis and primary erythromelalgia were added, and Schaaf–Yang syndrome was included in an existing disease group.
In July, the list was supplemented with Rafiq syndrome. The latest August expansion increased the number of entries to 305.
What Is Dup15q
Dup15q is a rare genetic disorder associated with the presence of extra copies of a region of chromosome 15.
There are two main forms: interstitial duplication and the isodicentric form, which is usually characterised by a more severe course.
The prevalence of the disease has not been precisely established. According to Orphanet, the birth prevalence of the most common isodicentric form is estimated at approximately 1 case per 30,000 newborns, although this figure may be underestimated.
The disease manifests at an early age.
The main clinical manifestations include:
— pronounced muscular hypotonia;
— delayed motor and intellectual development;
— significant speech impairment or absence of speech;
— autism spectrum disorders;
— epilepsy.
Epileptic seizures may be severe and poorly responsive to treatment. The diagnosis is confirmed by genetic testing.
Is There Specific Therapy
There is currently no specific therapy for Dup15q. Treatment is mainly aimed at controlling epilepsy, correcting developmental and speech disorders, behavioural therapy, and rehabilitation.
At the same time, attempts have been made to develop new treatments.
Roche studied basmisanil, a GABA-A receptor modulator, in a Phase II clinical trial directly in children with Dup15q. The study was terminated early by the company's decision, unrelated to the safety or tolerability of the drug.
Takeda studied soticlestat in Phase II as an adjunctive therapy for epileptic seizures in patients with Dup15q. The drug was not aimed at the genetic cause of the disease but was investigated to control one of its most severe manifestations.
The study did not produce a convincing signal of reduced seizure frequency in the Dup15q group. In 2025, Takeda discontinued the soticlestat development programme following unsuccessful Phase III trials in other epileptic syndromes.
Thus, neither in Russia nor worldwide is there currently a registered disease-modifying therapy for this condition.
Source: Russian Ministry of Health — List of Rare Orphan Diseases
The list now contains 305 entries.
How the List Expanded in 2026In 2026, the list of rare diseases was expanded several times.
In March, it was supplemented with congenital dyskeratosis, neurodevelopmental disorder associated with the HNRNPH2 gene, chronic hypoparathyroidism, and uveal melanoma. Subsequently, chronic hypoparathyroidism was removed.
In June, desmoid-type fibromatosis and primary erythromelalgia were added, and Schaaf–Yang syndrome was included in an existing disease group.
In July, the list was supplemented with Rafiq syndrome. The latest August expansion increased the number of entries to 305.
What Is Dup15qDup15q is a rare genetic disorder associated with the presence of extra copies of a region of chromosome 15.
There are two main forms: interstitial duplication and the isodicentric form, which is usually characterised by a more severe course.
The prevalence of the disease has not been precisely established. According to Orphanet, the birth prevalence of the most common isodicentric form is estimated at approximately 1 case per 30,000 newborns, although this figure may be underestimated.
The disease manifests at an early age.
The main clinical manifestations include:
— pronounced muscular hypotonia;
— delayed motor and intellectual development;
— significant speech impairment or absence of speech;
— autism spectrum disorders;
— epilepsy.
Epileptic seizures may be severe and poorly responsive to treatment. The diagnosis is confirmed by genetic testing.
Is There Specific TherapyThere is currently no specific therapy for Dup15q. Treatment is mainly aimed at controlling epilepsy, correcting developmental and speech disorders, behavioural therapy, and rehabilitation.
At the same time, attempts have been made to develop new treatments.
Roche studied basmisanil, a GABA-A receptor modulator, in a Phase II clinical trial directly in children with Dup15q. The study was terminated early by the company's decision, unrelated to the safety or tolerability of the drug.
Takeda studied soticlestat in Phase II as an adjunctive therapy for epileptic seizures in patients with Dup15q. The drug was not aimed at the genetic cause of the disease but was investigated to control one of its most severe manifestations.
The study did not produce a convincing signal of reduced seizure frequency in the Dup15q group. In 2025, Takeda discontinued the soticlestat development programme following unsuccessful Phase III trials in other epileptic syndromes.
Thus, neither in Russia nor worldwide is there currently a registered disease-modifying therapy for this condition.
Source: Russian Ministry of Health — List of Rare Orphan Diseases
