Clinical and genetic characteristics of a patient with phosphoribosyl pyrophosphate synthetase 1 deficiency and a systematic literature review.

Phosphoribosylpyrophosphate synthetase 1 (PRS-I) is an enzyme involved in nucleotide metabolism. Pathogenic variants in the PRPS1 are rare and PRS-I deficiency can manifest as three clinical syndromes: X-linked non-syndromic sensorineural deafness (DFN2), X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5) and Arts syndrome. We present a Slovenian patient with PRS-I enzyme deficiency due to a novel pathogenic variant - c.424G > A (p.Val142Ile) in the PRPS1 gene, who presented with gross motor impairment, severe sensorineural deafness, balance issues, ataxia, and frequent respiratory infections. In addition, we report the findings of a systemic literature review of all described male cases of Arts syndrome and CMTX5 as well as intermediate phenotypes. As already proposed by other authors, our results confirm PRS-I deficiency should be viewed as a phenotypic continuum rather than three separate syndromes because there are multiple reports of patients with an intermediary clinical presentation.

A patient with Baller-Gerold syndrome and midline NK/T lymphoma.

Three autosomal recessive disorders are associated with mutations in the RECQL4 gene: Rothmund-Thomson syndrome (RTS), Baller-Gerold syndrome (BGS), and RAPADILINO syndrome. BGS is characterized by two major clinical abnormalities: craniosynostosis and preaxial limb anomalies but not cancer development. We performed RECQL4 mutation detection in a patient with BGS and several clinical signs of RTS who developed a midline NK/T-cell lymphoma. Sequencing was used to identify RECQL4 mutations, and RNA analysis was used to examine expression of mRNA in leukocytes. The patient was found to be compound heterozygous for two mutations in exon 15, namely c.[2492_2493delAT] + c.[2506_2518del13bp]. We found that only the allele with 13 bp deletion was expressed in blood leukocytes. Our patient showed severe phenotypic abnormalities, with clinical signs of both BGS and RTS. She developed an extranodal NK/T-cell lymphoma, which is extremely rare in children of her age and is the first described case of BGS with development of a cancer. This case of a RECQL4-related disorder highlights the significant phenotypic overlap between the classically delineated RECQL4-associated syndromes and questions the need to redefine or combine these clinical entities.