Genotype and phenotype characterization of primary hypertrophic osteoarthropathy type 2 and chronic enteropathy associated with SLCO2A1: Report of two cases and literature review.

Autosomal recessive type 2 primary hypertrophic osteoarthropathy (PHOAR2) and chronic enteropathy associated with SLCO2A1 (CEAS) are two entities caused by pathogenic variants (PVs) in the SLCO2A1 gene that can coexist or occur independently from one another. We report two cases of PHOAR2 in Mexico with concomitant CEAS and conducted a review of the literature of the reported cases of PHOAR2 and/or CEAS to analyze the relationship between their genotype and phenotype presentation. The patients from our Institution with classical PHOAR2 phenotype and CEAS, harbored SLCO2A1 c.547G > A and c.1768del variants. We reviewed 232 cases, of which 86.6% were of Asian origin, and identified 109 different variants in SLCO2A1. Intron 7, exon 13, and exon 4 were predominantly affected. The two most common PVs were c.940 + 1G > A and c.1807C > T. We found a statistically significant association between SLCO2A1 variants located in intron 7, exons 12, and 13 and the development of CEAS. Missense variants were more frequent in isolated PHOAR2, while a greater proportion of protein-truncating variants (PTVs) were found in CEAS. Further investigation is imperative to elucidate the underlying pathophysiological mechanisms associated with CEAS, thereby facilitating the identification of effective therapeutic interventions.

Primary hypertrophic osteoarthropathy: genetics, clinical features and management.

Primary hypertrophic osteoarthropathy (PHO) is a genetic disorder mainly characterized by clubbing fingers, pachydermia and periostosis. Mutations in the HPGD or SLCO2A1 gene lead to impaired prostaglandin E2 (PGE2) degradation, thus elevating PGE2 levels. The identification of the causative genes has provided a better understanding of the underlying mechanisms. PHO can be divided into three subtypes according to its pathogenic gene and inheritance patterns. The onset age, sex ratio and clinical features differ among subtypes. The synthesis and signaling pathways of PGE2 are outlined in this review. Cyclooxygenase-2 (COX-2) is the key enzyme that acts as the rate-limiting step for prostaglandin production, thus COX-2 inhibitors have been used to treat this disease. Although this treatment showed effective results, it has side effects that restrain its use. Here, we reviewed the genetics, clinical features, differential diagnosis and current treatment options of PHO according to our many years of clinical research on the disease. We also discussed probable treatment that may be an option in the future.

Pachydermoperiostosis with bilateral ptosis and its associated systemic comorbidities: a rare case report.

Pachydermoperiostosis is a rare genetic disease known as primary or idiopathic hypertrophic osteoarthropathy (HOA)/Touraine-Solente-Gole syndrome. It is an autosomal dominant or recessive disorder comprising digital clubbing, periostosis, hyperhidrosis, and pachydermia (thickening of facial skin). Ocular manifestations are uncommon; however, blepharoptosis may occur. This case presented with severe bilateral ptosis due to the disease progression. A large 20 mm upper lid resection with levator advancement was performed to improve his ability to see. This is the first reported case of pachydermoperiostosis (PDP) in Jamaica. We present a rare case of pachydermoperiostosis with severe blepharoptosis, who attained a good result with surgical intervention.

Reclassification of the HPGD p.Ala13Glu variant causing primary hypertrophic osteoarthropathy.

Here, we highlight the case of a 31-yr-old man who had clinical features of primary hypertrophic osteoarthropathy (PHOAR) and harbored a homozygous variant (c.38C > A, p.Ala13Glu) in the HPGD gene, as indicated by whole-exome sequencing (WES). This variant has been previously classified by our laboratory as a variant of uncertain significance (VUS). However, another patient with the same phenotype and the same homozygous variant in HPGD was subsequently reported. In reassessing the variant, the absence of this variant in the gnomAD population database, supporting computational predictions, observation in homozygosity in two probands, and specificity of the phenotype for HPGD, all provide sufficient evidence to reclassify the HPGD c.38C > A, p.Ala13Glu variant as likely pathogenic.

Touraine-Solente-Gole syndrome: pathogenic variant in SLCO2A1 presented with polyarthralgia and digital clubbing.

BACKGROUND: Primary Hypertrophic Osteoarthropathy (PHO), also known as Touraine-Solente-Gole Syndrome, is a rare, multisystemic autosomal recessive disorder caused by pathogenic variants in the 15-hydroxyprostaglandin dehydrogenase (HPGD) or Solute Carrier Organic Anion Transporter Family Member 2A1 (SLCO2A1) genes. However, autosomal dominant transmission has also been described in some families with incomplete penetrance. PHO usually starts in childhood or adolescence, presenting with digital clubbing, osteoarthropathy, and pachydermia. We described a complete form of the syndrome in a male patient with a homozygous variant in the SLCO2A1 gene (c.1259G > T). CASE PRESENTATION: A 20-year-old male was referred to our Pediatric Rheumatology Clinic with a five-year history of painful and swollen hands, knees, ankles and feet, prolonged morning stiffness and relief with non-steroidal antiinflammatory drugs. He also reported late onset facial acne and palmoplantar hyperhidrosis. Family history was irrelevant and parents were non-consanguineous. On clinical examination, he presented clubbing of the fingers and toes, moderate acne and marked facial skin thickening with prominent scalp folds. He had hand, knee, ankles and feet swelling. Laboratory investigations showed elevated inflammatory markers. Complete blood count, renal and hepatic function, bone biochemistry were normal, as well as immunological panel. Plain radiographs revealed soft tissue swelling, periosteal ossification and cortical thickening of the skull, phalanges, femur and toe acroosteolysis. Due to the absence of other clinical signs suggesting a secondary cause, we suspected PHO. A genetic study revealed a likely pathogenic variant, c.1259G > T(p.Cys420Phe), in homozygosity in the SLCO2A1 gene, thus confirming the diagnosis. The patient started oral naproxen with significant clinical improvement. CONCLUSIONS: PHO should be kept in the differential diagnosis of inflammatory arthritis affecting children, often misdiagnosed as Juvenile Idiopathic Arthritis (JIA). To the best of our knowledge, this is the second genetically confirmed case of PHO in a Portuguese patient (first variant c.644 C > T), both made at our department.

Novel pathogenic variants in SLCO2A1 causing autosomal dominant primary hypertrophic osteoarthropathy.

Primary hypertrophic osteoarthropathy (PHO), or pachydermoperiostosis, is characterized by a clinical association including digital clubbing, periostosis and pachydermia. SLCO2A1 and HPGD genes are both responsible for PHO. The pathology is classically defined as an autosomal recessive disorder with clinical variability ranging from a mild to more severe phenotype. However, the hypothesis for an autosomal dominant form suggested for a long time was only demonstrated for the first time in 2021 for SLCO2A1. We aimed to detect a second pathogenic variant by a deep sequencing of the entire SLCO2A1 and HPGD genes, associated with functional transcription analysis in PHO patients harboring only one heterozygous variant. Among 10 PHO patients, 4 presented a single pathogenic or probably pathogenic novel variant in SLCO2A1 in heterozygous status (NM_005630.3: c.234+1G > A, c.1523_1524delCT, c.1625G > A and c.31delC), and the others carried homozygous pathogenic variants. For heterozygous forms, we found no additional pathogenic variant in HPGD or SLCO2A1. PHO can be a dominant form with age at disease onset later than that for the recessive form. This dominant form is not exceptional in young adults. In conclusion, both modes of inheritance of PHO explain the clinical variability and the difference in age at disease onset. Molecular analysis is especially required in the incomplete form to distinguish it from secondary hypertrophic osteoarthropathy.

Pachydermoperiostosis with Hearing Loss.

A 21-year-old unmarried man, born of a non-consanguineous marriage, presented to the dermatology department with progressive thickening of the facial skin and eyelids, plus increased folds over his forehead for the last 5 months. He also complained of progressive enlargement of his hands and feet, with intermittent joint pains in his wrists, elbows, and ankles, along with occasional abdominal pain. He had a hearing loss and increased sweating. (SKINmed. 2022;20:311-313).

Familial Touraine-Solente-Gole syndrome.

Touraine-Solente-Gole syndrome is a rare, autosomal dominant multisystem disorder arising from dysregulated prostaglandin synthesis due to underlying genetic defects. Early symptoms are related to skin and soft tissue involvement (coarse facial features, widening of wrists, etc) and may thus be overlooked unless a careful physical examination is carried out. Secondary causes of pachydermoperiosteitis must always be looked for in such patients. During evaluation, a systemic review of all organ systems should be carried out to identify asymptomatic or subclinical involvement of organ systems and identify means to avoid disease progression. Treatment options are limited to steroids and non-steroidal anti-inflammatory drugs. In the absence of definitive guidelines, clinical decisions are largely case based, with no definite duration of drug therapy or screening of potential malignancies outlined in current literature. Mental health and social rehabilitation of these patients due to their disfiguring deformities are an unmet need.

Differential Diagnosis of Acromegaly: Pachydermoperiostosis Two New Cases from Turkey

Pachydermoperiostosis (PDP), also known as primary hypertrophic osteoarthropathy, is a rare genetic disorder characterized by pachyderma and periostosis. Acromegaly is a condition caused by excessive secretion of growth hormone (GH) leading to elevated insulin-like growth factor 1 levels, and is characterised by somatic overgrowth and physical disfigurement, notably affecting hands and feet. We present two cases referred with an initial diagnosis of acromegaly that were ultimately diagnosed as PDP. Case 1: A 17 year-old boy presented with enlargement in both feet and hands, finger clubbing, swelling in knee joints, knee pain, coarsening of facial skin lines and forehead skin, and excessive sweating which increased gradually over five years. There were prominent skin folds on the forehead, face, and eyelids. Also, there was an enlargement in both hands and clubbing of the fingers. There was marked swelling in the knee joints and ankles. Genetic analysis revealed a novel homozygous variant NM_005630: c.31C>T (p.Q11*) in the SLCO2A1 gene. Case 2: A 16 year-old boy presented with coarsening of forehead skin and scalp, excessive sweating, and pain in the elbow and knee over three years. Skin folds were prominent on the forehead and scalp. Genetic analysis revealed a homozygous variant NM_005630.2:c.86delG (p.G29Afs*48) in the SLCO2A1 gene. Such clinical presentation contemporaneous with normal GH level and prominent radiological abnormalities prompted the diagnosis of PDP. In conclusion, PDP is a very rare osteoarthrodermopathic disorder with clinical and radiographic presentation that may mimic acromegaly. In the evaluation of patients with acromegaloid appearance, PDP should be considered as a differential diagnosis.