Further delineation of cerebro-osteo-nephrosis syndrome

Novel TP53RK variants cause varied clinical features of Galloway-Mowat syndrome without nephrotic syndrome in three unrelated Chinese patients

Objectives

Galloway-Mowat syndrome-4 (GAMOS4) is a very rare renal-neurological disease caused by TP53RK gene mutations. GAMOS4 is characterized by early-onset nephrotic syndrome, microcephaly, and brain anomalies. To date, only nine GAMOS4 cases with detailed clinical data (caused by eight deleterious variants in TP53RK) have been reported. This study aimed to examine the clinical and genetic characteristics of three unrelated GAMOS4 patients with TP53RK gene compound heterozygous mutations.

Methods

Whole-exome sequencing (WES) was used to identify four novel TP53RK variants in three unrelated Chinese children. Clinical characteristics such as biochemical parameters and image findings of patients were also evaluated. Furthermore, four studies of GAMOS4 patients with TP53RK variants were reviewed. In addition, clinical and genetic features were described after a retrospective analysis of clinical symptoms, laboratory data, and genetic test results.

Results

The three patients showed facial abnormalities, developmental delays, microcephaly, and aberrant cerebral imaging. Furthermore, patient 1 had slight proteinuria, while patient 2 had epilepsy. However, none of the individuals had nephrotic syndrome, and all were alive for more than 3 years of age. This is the first study to assess four variants in the TP53RK gene (NM_033550.4: c.15_16dup/p.A6Efs*29, c.745A > G/p.R249G, c.185G > A/p.R62H, and c.335A > G/p.Y112C).

Conclusion

The clinical characteristics of the three children with TP53RK mutations are significantly different from the known GAMOS4 traits, including early nephrotic syndrome and mortality mainly occurring in the first year of life. This study provides insights into the pathogenic TP53RK gene mutation spectrum and clinical phenotypes of GAMOS4.

Diagnostic dilemmas in four infants with nephrotic syndrome, microcephaly and severe developmental delay

We present four cases with nephrotic syndrome, microcephaly and severe developmental delay. In the differential diagnosis the Galloway-Mowat syndrome, PEHO syndrome, ARC syndrome and the carbohydrate-deficient glycoprotein (CDG) syndrome are considered and discussed. One case may fall into the Galloway-Mowat spectrum and another case was diagnosed with the CDG syndrome. This case is the third report of a nephrotic syndrome as a part of the CDG syndrome. Two remaining cases with cerebellar and brain stem atrophy, and without major histopathological changes in the kidney were left without a definite unifying diagnosis and may well represent a different unknown condition. Although microcephaly and nephrotic syndrome with or without hiatus hernia has been equated with Galloway-Mowat syndrome in the literature, the brain and renal pathology in these reported cases has been very variable. It is likely that this group as a whole is aetiologically heterogeneous.