Elevated Urinary Levels of 8-Hydroxy-2’-deoxyguanosine in a Japanese Child of Xeroderma Pigmentosum/Cockayne Syndrome Complex with Infantile Onset of Nephrotic Syndrome

Elevated Urinary Levels of 8-Hydroxy-2'-deoxyguanosine in a Japanese Child of Xeroderma Pigmentosum/Cockayne Syndrome Complex with Infantile Onset of Nephrotic Syndrome

DAIKI KONDO,¹ ATSUKO NOGUCHI,¹ HIROAKI TAMURA,¹ SATOKO TSUCHIDA,² IKUKO TAKAHASHI,¹ HIROKI KUBOTA,¹ TAMAMI YANO,¹ CHIKAKO OYAMA,¹ YUKIO SAWAISHI,³ SHINICHI MORIWAKI⁴ and TSUTOMU TAKAHASHI¹

¹Department of Pediatrics, Akita University Graduate School of Medicine, Akita, Akita, Japan
²Devision of Pediatrics, Akita Red Cross Hospital, Akita, Akita, Japan
³Devision of Pediatrics, Akita Prefectural Center on Development and Disability, Akita, Akita, Japan
⁴Department of Dermatology, Osaka Medical College, Takatsuki, Osaka, Japan

Nucleotide excision repair (NER) is an essential biological pathway protecting against ultraviolet light-induced DNA damage. Deficient NER causes a group of rare genetic disorders including two autosomal recessive diseases, xeroderma pigmentosum (XP) and Cockayne syndrome (CS). In addition to the cutaneous photosensitivity shared in XP and CS, CS is featured by growth failure, neurological deterioration, microcephaly, and deep sunken eyes. XP/CS complex is an extremely rare type of NER disorder with a distinct phenotype that is characterized by the skin and eye pathology of XP and the somatic and neurological abnormalities of CS. Some of CS cases have been reported to be complicated with renal failure, but the genetic background or the etiology of the renal failure has not been reported. We herein report a 1-year-old Japanese boy with XP/CS complex, complicated by nephrotic syndrome. Diagnosis was confirmed by the presence of compound heterozygous mutations, G47R (c.139G>A) and R616G (c.1846C>G), in the excision repair cross-complementation group 2 (ERCC2) gene. The kidney biopsies, performed at the age of 1 year and 2 months, revealed diffuse expansion of the mesangial matrix and segmental glomerulosclerosis under light microscopy, and diffused thin capillary walls with partially lamellated regions under electron microscopy. Notably, high levels of urinary 8-hydroxy-2'-deoxyguanosin, known as an oxidative stress marker, were observed during the clinical course. The patient died at the age of 1 year and 11 months because of renal failure. We suggest the involvement of oxidative stress in the pathogenesis of nephrotic syndrome in NER disorders.

keywords —— Cockayne syndrome; ERCC2 gene; nephrotic syndrome; 8-OHdG; xeroderma pigmentosum

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Tohoku J. Exp. Med., 2016, 239, 231-235

Correspondence: Tsutomu Takahashi, MD, Ph.D, Department of Pediatrics, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita, Akita 010-8543, Japan.

e-mail: tomy@med.akita-u.ac.jp