A family with Townes-Brocks syndrome with congenital hypothyroidism and a novel mutation of the SALL1 gene

CRISPR/Cas-edited pigs for personalized medicine: more than preclinical test-system

Novel CRISPR-Cas-based genome editing tools made it feasible to introduce a variety of precise genomic modifications in the pig genome, including introducing multiple edits simultaneously, inserting long DNA sequences into specifically targeted loci, and performing nucleotide transitions and transversions. Pigs serve as a vital agricultural resource and animal model in biomedical studies, given their advantages over the other models. Pigs share high similarities to humans regarding body/organ size, anatomy, physiology, and a metabolic profile. The pig genome can be modified to carry the same genetic mutations found in humans to replicate inherited diseases to provide preclinical trials of drugs. Moreover, CRISPR-based modification of pigs antigen profile makes it possible to offer porcine organs for xenotransplantation with minimal transplant rejection responses. This review summarizes recent advances in endonuclease-mediated genome editing tools and research progress of genome-edited pigs as personalized test-systems for preclinical trials and as donors of organs with human-fit antigen profile.

Graphical abstract:

Novel mutation in the SALL1 gene in a four-generation Chinese family with uraemia: A case report

BACKGROUND

Approximately 10% of adults and nearly all children who receive renal replacement therapy have inherited risk factors or are related to genetic factors. In the past, due to the limitations of detection technology and the nonspecific manifestations of uraemia, the etiological diagnosis is unclear. In addition to common monogenic diseases and complex disorders, advanced testing techniques have led to the recognition of more hereditary renal diseases. Here, we report a four-generation Chinese family in which four individuals had a novel SALL1 mutation and presented with uraemia or abnormal urine tests.

CASE SUMMARY

A 32-year-old man presented with end-stage renal disease with a 4-year history of dialysis. His father and paternal aunt both had a history of unexplained renal failure with haemodialysis, and his 10-year-old daughter presented with proteinuria. The patient had multiple congenital abnormalities, including bilateral overlapping toes, unilateral dysplastic external ears, and sensorineural hearing loss. His family members also presented with similar defects. Genetic testing revealed that the proband carried a novel heterozygous shift mutation in SALL1_exon 2 (c.3437delG), and Sanger sequencing confirmed the same mutation in all affected family members.

CONCLUSION

We report a novel SALL1 exon 2 (c.3437delG) mutation and clinical syndrome with kidney disease, bilateral overlapping toes, unilateral dysplastic external ears, and sensorineural hearing loss in a four-generation Chinese family.

Adult diagnosis of Townes-Brocks syndrome with renal failure: Two related cases and review of literature

Townes-Brocks syndrome (TBS) is a rare autosomal dominant syndrome, resulting from heterozygous variant in SALL1 gene and initially characterized by the triad of anorectal, thumb, and ear malformations. Essentially described in children, adult case reports are uncommon. Renal involvement has already been reported in adults and children but poorly described. Structural abnormalities such as hypodysplasia, unilateral renal agenesis or multicystic kidneys have been described, as well as functional impairment (with or without structural abnormalities) that may progress to end-stage renal disease (ESRD). We report two adult cases (mother and daughter) which exhibited kidney hypoplasia (focal and segmental glomerulosclerosis for the mother) and ESRD. The mother had unilateral polydactyly. TBS was suggested after physical examination. TBS diagnosis was confirmed by identification of a SALL1 variant. We conducted a literature review to evaluate the renal anomalies in TBS cases diagnosed in adulthood. Among 44 adult cases of TBS with genetic confirmation (including our two cases), 10 had kidney disease. The circumstances of renal failure diagnosis were incidental findings (2/5), gout (2/5), or repeated episodes of pyelonephritis (1/5). The median age of kidney disease diagnosis was 30 years old and of renal transplant 49 years old. The most frequent renal malformation was bilateral kidney hypoplasia. TBS is probably underestimated in adulthood and this report highlights that less obvious elements of morphology such as dysplasic ears can facilitate the diagnosis of TBS. As long-term prognosis of renal involvement in TBS patients remains largely unknown, a regular evaluation is required throughout life for patients.

Endocrine abnormalities in Townes-Brocks syndrome

Townes-Brocks syndrome is a recognizable variable pattern of malformation caused by mutations to the SALL1 gene located on chromosome 16q12.1. Only three known cases of Townes-Brocks syndrome with proven SALL1 gene mutation and concurrent endocrine abnormalities have been previously documented to our knowledge [Kohlhase et al., 1999; Botzenhart et al., 2005; Choi et al., 2010]. We report on two unrelated patients with Townes-Brocks syndrome who share an identical SALL1 mutation (c.3414_3415delAT), who also have endocrine abnormalities. Patient 1 appears to be the first known case of growth hormone deficiency, and Patient 2 extends the number of documented mutation cases with hypothyroidism to four. We suspect endocrine abnormalities, particularly treatable deficiencies, may be an underappreciated component to Townes-Brocks syndrome.