Research Centre for Medical Genetics
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The DNA-diagnostics Laboratory first studied the structure and prevalence of BH4-dependent forms of hyperphenylalaninemia in the Russian Federation

Timely identification of patients with tetrahydrobiopterin (BH4)-deficient type of hyperphenylalaninemia (HPABH4) is important for the proper therapy to avoid complications. Patients with HPABH4 often receive the same treatment (diet therapy) as patients with classical phenylalketonuria due to phenylalanine hydroxylase (PAH) deficiency. Patients with HPABH4 do not receive tetrahydrobiopterin replacement therapy until the molecular genetic methods confirm the diagnosis. The published study examined a cohort of 30 Russian patients with HPABH4 who were identified to have gene variants causing different types of HPA. The study showed that HPABH4 type A was predominant and represented 83.3% of all HPABH4 cases. Spectrum of PTS gene mutations and the most frequent variants p.Thr106Met - 32%, p.Asn72Lys - 20%, p.Arg9His - 8%, p.Ser32Gly - 6% were identified. In addition, 7 new variants of the PTS gene and 3 new variants of the QDPR gene were found. The HPABH4prevalence is estimated at 0.5-0.9% of all HPA cases in Russia, which is significantly lower than the average for European, Chinese and Saudi Arabian countries.  The findings indicated the necessity of introducing differential diagnosis of HPABH4 into the practice of neonatal screeningH4,

Polina Gundorova ,Irina A. Kuznetcova,Galina V. Baydakova,Anna A. Stepanova,Yulia S. Itkis,Victoria S. Kakaulina,Irina P. Alferova,Lidya V. Lyazina,Lilya P. Andreeva,Ilya Kanivets,Ekaterina Y. Zakharova,Sergey I. Kutsev,Aleksander V. Polyakov. BH4-deficient hyperphenylalaninemia in Russia. Plos ONE. April 6, 2021.