From gene discovery to new biological mechanisms: heparanases and congenital urinary bladder disease

Botulinum toxin to improve facial expression in a patient with Urofacial (Ochoa) Syndrome

The Urofacial or Ochoa Syndrome is a very rare congenital disorder that includes vesical bladder dysfunction and a peculiar inverse facial expression, which brings patients to express a sad-crying face while they intend to laugh. Up-to-date treatments have addressed only the urological side of this disease. However, also the impaired facial mimicry has a strong impact on patients' quality of life. We treated a young patient with Botulinum toxin to address this impairment and obtained pleasing results, including a harmonic smile and a very satisfied patient. To the best of our knowledge, this is the first time that the use of Botulinum toxin is reported in literature to address the facial expression component of this disease.

Expanding the HPSE2 Genotypic Spectrum in Urofacial Syndrome, A Disease Featuring a Peripheral Neuropathy of the Urinary Bladder

Urofacial (also called Ochoa) syndrome (UFS) is an autosomal recessive congenital disorder of the urinary bladder featuring voiding dysfunction and a grimace upon smiling. Biallelic variants in HPSE2, coding for the secreted protein heparanase-2, are described in around half of families genetically studied. Hpse2 mutant mice have aberrant bladder nerves. We sought to expand the genotypic spectrum of UFS and make insights into its pathobiology. Sanger sequencing, next generation sequencing and microarray analysis were performed in four previously unreported families with urinary tract disease and grimacing. In one, the proband had kidney failure and was homozygous for the previously described pathogenic variant c.429T>A, p.(Tyr143*). Three other families each carried a different novel HPSE2 variant. One had homozygous triplication of exons 8 and 9; another had homozygous deletion of exon 4; and another carried a novel c.419C>G variant encoding the missense p.Pro140Arg in trans with c.1099-1G>A, a previously reported pathogenic splice variant. Expressing the missense heparanase-2 variant in vitro showed that it was secreted as normal, suggesting that 140Arg has aberrant functionality after secretion. Bladder autonomic neurons emanate from pelvic ganglia where resident neural cell bodies derive from migrating neural crest cells. We demonstrated that, in normal human embryos, neuronal precursors near the developing hindgut and lower urinary tract were positive for both heparanase-2 and leucine rich repeats and immunoglobulin like domains 2 (LRIG2). Indeed, biallelic variants of LRIG2 have been implicated in rare UFS families. The study expands the genotypic spectrum in HPSE2 in UFS and supports a developmental neuronal pathobiology.

Dual diagnosis of Ochoa syndrome and Niemann-Pick disease type B in a consanguineous family

OBJECTIVES

Ochoa syndrome (UFS1; Urofacial syndrome-1) is a very rare autosomal recessive disorder caused by mutations in the HPSE2 gene that results bladder voiding dysfunction and somatic motor neuropathy affecting the VIIth cranial nerve. Niemann-Pick disease is a rare autosomal recessive lysosomal storage disorder with systemic involvement resulting from sphingomyelinase deficiency and generally occurs via mutation in the sphingomyelin phosphodiesterase-1 gene (SMPD1).

CASE PRESENTATION

Here, we report a 6-year-old girl with symptoms such as urinary incontinence, recurrent urinary tract infections, peculiar facial expression, mainly when smiling, hypertelorism, constipation, incomplete closure of eyelids during sleep and splenomegaly. Homozygote mutations in two different genes responsible for two distinct syndromes were detected in the patient. Homozygous NM_000543.5:c.502G>A (p.Gly168Arg) mutation was found in the SMPD1 gene causing Niemann-Pick disease. In addition, some of the clinical features were due to a novel homozygous mutation identified in the HPSE2 gene, NM_021828.5:c.755delA (p.Lys252SerfsTer23).

CONCLUSIONS

Here, we discuss about the importance of considering dual diagnosis in societies where consanguineous marriages are common. Accurate diagnosis of the patient is very important for the management of the diseases and prevention of complications.

Urofacial (ochoa) syndrome: A literature review

The Urofacial or Ochoa Syndrome (UFS or UFOS) is characterized by an inverted facial expression (those affected seem crying while smiling) associated with lower urinary tract dysfunction without evident obstructive or neurological cause. It is associated with autosomal recessive inheritance mutations in the HPSE2 gene, located at 10q23-q24, and the LRGI2 gene, located in 1p13.2; however, in up to 16% of patients, no associated mutations have been found. Recent evidence suggests that these genes are critical to an adequate neurological development to the lower urinary tract and that the origin of the disease seems to be due to peripheral neuropathy. There is clinical variability among patients with UFS and not all present the classic two components, and it has even been genetically confirmed in patients with a prior diagnosis of Hinman Syndrome or other bladder dysfunctions. Also, the presence of nocturnal lagophthalmos in these patients was recently described. Early recognition and timely diagnosis are critical to preventing complications such as urinary tract infections or chronic kidney disease. Next, the history of Urofacial Syndrome, the advances in its pathophysiology, and its clinical characteristics is reviewed.

Lrig2 and Hpse2, mutated in urofacial syndrome, pattern nerves in the urinary bladder

Mutations in leucine-rich-repeats and immunoglobulin-like-domains 2 (LRIG2) or in heparanase 2 (HPSE2) cause urofacial syndrome, a devastating autosomal recessive disease of functional bladder outlet obstruction. It has been speculated that urofacial syndrome has a neural basis, but it is unknown whether defects in urinary bladder innervation are present. We hypothesized that urofacial syndrome features a peripheral neuropathy of the bladder. Mice with homozygous targeted Lrig2 mutations had urinary defects resembling those found in urofacial syndrome. There was no anatomical blockage of the outflow tract, consistent with a functional bladder outlet obstruction. Transcriptome analysis revealed differential expression of 12 known transcripts in addition to Lrig2, including 8 with established roles in neurobiology. Mice with homozygous mutations in either Lrig2 or Hpse2 had increased nerve density within the body of the urinary bladder and decreased nerve density around the urinary outflow tract. In a sample of 155 children with chronic kidney disease and urinary symptoms, we discovered novel homozygous missense LRIG2 variants that were predicted to be pathogenic in 2 individuals with non-syndromic bladder outlet obstruction. These observations provide evidence that a peripheral neuropathy is central to the pathobiology of functional bladder outlet obstruction in urofacial syndrome, and emphasize the importance of LRIG2 and heparanase 2 for nerve patterning in the urinary tract.