Exome sequencing identifies compound heterozygous PKHD1 mutations as a cause of autosomal recessive polycystic kidney disease

Background Autosomal recessive polycystic kidney disease （ARPKD） is a rare inherited disease, which is a disorder with multiple organ involvement, mainly the kidney and liver. It is caused by mutations in the PKHD1 gene. Here, we reported the clinical characteristics of a case with ARPKD and analyze the genetic features of this patient as well as of his father using targeted exome sequencing and Sanger sequencing. Methods Genomic DNA was extracted from peripheral blood leukocytes obtained from a patient with ARPKD. The mutations were identified using exome sequencing and confirmed by Sanger sequencing. Results The patient was diagnosed as ARPKD based on ultrasonography and abdominal computed tomography which showed polycystic changes, multiple calcinosis of both kidneys, and multiple dilated bile ducts of the liver. Compound heterozygous PKHD1 gene mutations A979G and G5935A, which lead to substitution of an asparagine for an aspartate at amino acid 327 （N327D） and a glycine for an arginine at amino acid 1979 （G1979R） respectively, were identified using targeted exome sequencing and confirmed by Sanger sequencing for the patient. In addition, the father of the patient was identified to be a carrier of heterozygous A979G mutation of this gene. Conclusions We identified that the compound heterozygous PKHD1 gene mutations are the molecular basis of the patient with ARPKD. Targeted exome sequencing is suitable for genetic diagnosis of single-gene inherited diseases like ARPKD in which the pathogenic gene is a large.

Possible PKHD1 Hot-spot Mutations Related to Early Kidney Function Failure or Hepatofibrosis in Chinese Children with ARPKD:A Retrospective Single Center Cohort Study and Literature Review

PKHD1 mutations are generally considered to cause autosomal recessive polycystic kidney disease(ARPKD).ARPKD is a rare disorder and one o f the most severe conditions leading to end-stage renal disease in childhood.With the biallelic deletion mutation,patients have difficulty in surviving the perinatal period,resulting in perinatal or neonatal death.This study retrospectively analyzed patient characteristics,imaging characteristics,laboratory examinations and family surveys from 7 Chinese children with different PKHD1 gene mutations diagnosed by high-throughput sequencing from January 2014 to February 2018.O f the 7 children,there were 3 males and 4 females.Eight missense mutations,two frameshift mutations,two deletion mutations,and two intronic slicing mutations were identified.Six of the mutations have not previously been identified.In the literature search,we identified a total of 29 Chinese children with PKHD1 mutations.The missense mutation c.2507T>C in exon 24 was found in one patient in our study,and five patients with liver fibrosis but normal renal function were reported in the literature.The missense mutation c.5935G>A in exon 37 was found in two patients in our study and three cases in the literature.Four patients had renal failure at an age as young as 1 year of those five patients with the missense mutation c.5935G>A in exon 37.It was concluded that:(1)Kidney length more than 2-3 SDs above the mean and early-onset hypertension might be associated with PKHDI-associated ARPICD;(2)The more enlarged the kidney size is,the lower the renal function is likely to be;(3)c.5935G>A may be a hot spot that leads to early renal failure in Chinese children with PKHD1 mutations;(4)c.2507T>C may be a hot-spot mutation associated with hepatic lesions in Chinese children with PKHD1.

Combined liver and kidney transplantation in children and long-term outcome

Combined liver-kidney transplantation(CLKT)is a rarely performed complex surgical procedure in children and involves transplantation of kidney and either whole or part of liver donated by the same individual(usually a cadaver)to the same recipient during a single surgical procedure.Most common indications for CLKT in children are autosomal recessive polycystic kidney disease and primary hyperoxaluria type 1.Atypical haemolytic uremic syndrome,methylmalonic academia,and conditions where liver and renal failure co-exists may be indications for CLKT.CLKT is often preferred over sequential liver-kidney transplantation due to immunoprotective effects of transplanted liver on renal allograft;however,liver survival has no significant impact.Since CLKT is a major surgical procedure which involves multiple and complex anastomosis surgeries,acute complications are not uncommon.Bleeding,thrombosis,haemodynamic instability,infections,acute cellular rejections,renal and liver dysfunction are acute complications.The long-term outlook is promising with over 80%5-year survival rates among those children who survive the initial six-month postoperative period.