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Diagnostics
Volume 15
Issue 21
10.3390/diagnostics15212773
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This is an early access version, the complete PDF, HTML, and XML versions will be available soon.
Article

Genotype–Phenotype Correlations and Shifting Diagnosis Age in Turkish Mucopolysaccharidosis Type II Patients: A Multicenter Retrospective Study

by
Havva Yazıcı
1,*,
Esra Kara
2,
Fatma Derya Bulut
2,
Merve Yoldaş Çelik
1,
Burcu Köşeci
2,
Fehime Erdem
1,
Ezgi Burgaç
2,
Ayşe Yüksel Yanbolu
1,
İrem Kaplan
2,
Asude Durmaz
3,
Ayça Aykut
3,
Ebru Canda
1,
Deniz Kor
2,
Sema Kalkan Uçar
1,
Eser Sözmen
4,
Mahmut Çoker
1 and
Halise Neslihan Önenli Mungan
2
1
Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ege University Faculty of Medicine, Izmir 35040, Turkey
2
Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Çukurova University Faculty of Medicine, Adana 01330, Turkey
3
Department of Medical Genetics, Ege University Faculty of Medicine, Izmir 35040, Turkey
4
Department of Biochemistry, Ege University Faculty of Medicine, Izmir 35040, Turkey
*
Author to whom correspondence should be addressed.
Diagnostics 2025, 15(21), 2773; https://doi.org/10.3390/diagnostics15212773 (registering DOI)
Submission received: 30 September 2025 / Revised: 25 October 2025 / Accepted: 30 October 2025 / Published: 31 October 2025
(This article belongs to the Section Clinical Diagnosis and Prognosis)
Versions Notes

Abstract

Background/Objectives: Mucopolysaccharidosis type II (MPS II) is an inherited metabolic disorder characterized by progressive neurologic and extra-neurologic findings. We aimed to explore the age at symptom onset and at diagnosis as well as contribute to the phenotype–genotype association with new observations of MPS II based on a broad series of patients in Turkey. Methods: The presented study was retrospective and descriptive. Data on molecular analysis results, the age of onset and diagnosis, diagnostic delays, neurologic and extra-neurologic symptoms, enzyme and urine glycosaminoglycan (GAG) level results, brain magnetic resonance imaging, echocardiography, and electromyography were reviewed. Results: A total of 46 MPS II patients from 40 families were involved. The mean diagnosis age was 40.1 ± 46.8 months, and the diagnostic delay was 19.7 ± 40.4 months. While the mean age of diagnosis of the first cases in the families was 45 ± 24 months, the mean age of diagnosis of the second cases was 14 ± 15 months. The mean age at diagnosis was 42 ± 18 months in the patient group born before 2010, while it was 28 ± 22 months in the patient group born in 2010 and after. The last measurement of the height SDS value showed a significant difference (p = 0.004) between the groups that started ERT before the age of three and those who began ERT at the age of three and above. Five patients showed an attenuated phenotype without neurologic involvement. The sequencing of the IDS gene revealed 25 distinct variants, with 8 novel variants that have yet to be documented in the existing literature. Conclusions: The findings from the observations of this Turkish MPS II cohort emphasize that the actual prevalence of MPS II is probably underestimated and that it has a broad spectrum of clinical phenotypes, even without neurological impairment. In children, specific warning signs—including a coarse facial appearance, abdominal distension, speech delays, and macrocephaly—should raise suspicion and prevent delays in diagnosis. Conducting urine GAG and enzyme analyses is crucial for cases with clinical suspicion. Our data showed that the age of diagnosis tended to decrease over the years.
Keywords: genotype; Hunter syndrome; IDS; idursulfase; mucopolysaccharidosis type II genotype; Hunter syndrome; IDS; idursulfase; mucopolysaccharidosis type II

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MDPI and ACS Style

Yazıcı, H.; Kara, E.; Bulut, F.D.; Çelik, M.Y.; Köşeci, B.; Erdem, F.; Burgaç, E.; Yanbolu, A.Y.; Kaplan, İ.; Durmaz, A.; et al. Genotype–Phenotype Correlations and Shifting Diagnosis Age in Turkish Mucopolysaccharidosis Type II Patients: A Multicenter Retrospective Study. Diagnostics 2025, 15, 2773. https://doi.org/10.3390/diagnostics15212773

AMA Style

Yazıcı H, Kara E, Bulut FD, Çelik MY, Köşeci B, Erdem F, Burgaç E, Yanbolu AY, Kaplan İ, Durmaz A, et al. Genotype–Phenotype Correlations and Shifting Diagnosis Age in Turkish Mucopolysaccharidosis Type II Patients: A Multicenter Retrospective Study. Diagnostics. 2025; 15(21):2773. https://doi.org/10.3390/diagnostics15212773

Chicago/Turabian Style

Yazıcı, Havva, Esra Kara, Fatma Derya Bulut, Merve Yoldaş Çelik, Burcu Köşeci, Fehime Erdem, Ezgi Burgaç, Ayşe Yüksel Yanbolu, İrem Kaplan, Asude Durmaz, and et al. 2025. "Genotype–Phenotype Correlations and Shifting Diagnosis Age in Turkish Mucopolysaccharidosis Type II Patients: A Multicenter Retrospective Study" Diagnostics 15, no. 21: 2773. https://doi.org/10.3390/diagnostics15212773

APA Style

Yazıcı, H., Kara, E., Bulut, F. D., Çelik, M. Y., Köşeci, B., Erdem, F., Burgaç, E., Yanbolu, A. Y., Kaplan, İ., Durmaz, A., Aykut, A., Canda, E., Kor, D., Uçar, S. K., Sözmen, E., Çoker, M., & Mungan, H. N. Ö. (2025). Genotype–Phenotype Correlations and Shifting Diagnosis Age in Turkish Mucopolysaccharidosis Type II Patients: A Multicenter Retrospective Study. Diagnostics, 15(21), 2773. https://doi.org/10.3390/diagnostics15212773

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