Acid Ceramidase Deficiency: Bridging Gaps between Clinical Presentation, Mouse Models, and Future Therapeutic Interventions

Farber disease (FD) and spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) are ultra-rare, autosomal-recessive, acid ceramidase (ACDase) deficiency disorders caused by ASAH1 gene mutations. Currently, 73 different mutations in the ASAH1 gene have been described in humans. These mutations lead to reduced ACDase activity and ceramide (Cer) accumulation in many tissues. Presenting as divergent clinical phenotypes, the symptoms of FD vary depending on central nervous system (CNS) involvement and severity. Classic signs of FD include, but are not limited to, a hoarse voice, distended joints, and lipogranulomas found subcutaneously and in other tissues. Patients with SMA-PME lack the most prominent clinical signs seen in FD. Instead, they demonstrate muscle weakness, tremors, and myoclonic epilepsy. Several ACDase-deficient mouse models have been developed to help elucidate the complex consequences of Cer accumulation. In this review, we compare clinical reports on FD patients and experimental descriptions of ACDase-deficient mouse models. We also discuss clinical presentations, potential therapeutic strategies, and future directions for the study of FD and SMA-PME.

Coelomic Granulomatous Fat Necrosis (Lipogranulomatosis) in an Umbrella Cockatoo (Cacatua alba)

A 28-year-old, female umbrella cockatoo (Cacatua alba) was evaluated because of lethargy, anorexia, regurgitation, and coelomic swelling of 6 month's duration, which corresponded to cessation of egg laying. Radiographs and ultrasound examination demonstrated extensive deposits of coelomic fat and an enlarged oviduct. Exploratory celiotomy demonstrated copious amounts of firm, nodular fat completely surrounding the gastrointestinal tract, resulting in extensive chronic adhesions between intestinal loops. Free yolk was present in the cranial left coelom, yolk coelomitis was diagnosed, and a salpingohysterectomy was performed. Two days after surgery, the bird stopped passing feces and began regurgitating after eating, and a colonic obstruction was demonstrated via contrast radiography. Euthanasia was elected, and necropsy revealed an obstruction of the distal colon caused by extraluminal compression by adhesions of firm, nodular fat. Histologic examination demonstrated extensive fat necrosis with granulomatous inflammation, characterized by cords of necrotic fat surrounded by multinucleated giant cells and epithelioid macrophages with scattered lymphocytes and plasma cells and rare heterophils. The clinical signs, gross lesions, and histologic lesions are characteristic of massive fat necrosis (lipogranulomatosis) in ruminants and mesenteric panniculitis in humans and companion mammals. This is the first report, to our knowledge, of this disease in psittacine birds.

Mechanical Blepharoptosis and Eyelid Swelling Caused by Silicone Oil

The purpose of this article is to report a case of upper eyelid mechanical ptosis caused by silicone oil migration in a Jordanian patient after pars plana vitrectomy and intraocular silicone oil injection. A 20-year-old male patient was referred to the oculoplastic clinic for the management of a left upper eyelid swelling and complete ptosis that developed 12 years after pars plana vitrectomy and silicone oil placement for retinal detachment secondary to perforating eye injury. Eye examination showed upper eyelid swelling and a complete ptosis induced by the weight of inflammatory tissue and silicone oil, as proved by histopathologic examination. We presumed that silicone oil had leaked through the pars plana vitrectomy ports or through a subtle traumatic perforation of the posterior segment, which might have been aggravated by increased intra-ocular pressure postoperatively. In conclusion, mechanical ptosis caused by silicone oil migration after retinal detachment surgery is rare and this is one of the few reports in the literature.