Galactosialidosis (GS) is an ultra-rare autosomal recessive lysosomal storage disorder caused by pathogenic variants in the CTSA gene. The resulting deficiency of protective protein/cathepsin A leads to reduced β-galactosidase and α-neuraminidase activity, causing multisystem involvement. While typical features include dysmorphic facies, organomegaly, skeletal dysplasia, and neurological impairment, dermatologic manifestations remain poorly characterized. We report a 9-month-old girl presenting with hepatosplenomegaly and diffuse dermal melanocytosis. Her history included nonimmune hydrops fetalis, congenital cataract, developmental delay, and recurrent respiratory infections. Clinical and radiological evaluation revealed coarse facial features, dysostosis multiplex, and periventricular white matter changes. Enzyme assay demonstrated markedly reduced β-galactosidase activity. Genetic testing identified a homozygous CTSA c.359T>C (p.Ile120Thr) variant, classified as likely pathogenic. Family screening revealed her 10-year-old brother carried the same variant in homozygosity. He exhibited milder features, including developmental delay, hearing loss, and skeletal abnormalities without cutaneous involvement or organomegaly. Enzymatic deficiency was confirmed in both siblings. This report highlights diffuse dermal melanocytosis as a possible novel cutaneous marker of GS, potentially aiding early recognition. It also illustrates intrafamilial phenotypic variability despite identical genotypes. Our findings underscore the importance of dermatologic clues in the diagnostic workup of lysosomal storage disorders and advocate for family-based genetic screening to identify asymptomatic or mildly affected individuals.

Here we report a Japanese patient with juvenile/adult-type galactosialidosis carrying a homozygous c.692+3A>G CTSA variant. Comprehensive genetic analyses including exome sequencing, chromosomal microarray and homozygosity mapping supported biallelic inheritance of this variant and suggested a founder effect in the Japanese population. Clinically, the patient exhibited typical features of the juvenile/adult-type galactosialidosis, with growth impairment noted during adolescence as a less conspicuous but relevant observation.

Galactosialidosis (GS) is a rare lysosomal storage disease (LSD) with variable onset caused by a defect in protective protein/cathepsin A (PPCA) encoded by the CTSA gene. The late-infantile onset is characterized by developmental delay, visceromegaly, coarse facies, and cherry-red macula. We report cases of late-infantile GS in a Thai-Lahu family, with affected members initially presenting with recurrent infections due to T-cell defects. The clinical features of LSD and cherry-red macula led us to perform lysosomal enzyme assays, which showed undetectable activity of PPCA. A novel homozygous missense CTSA variant (NM_000308.4): c.1307A > G (p.Gln436Arg) was identified in affected individuals. In vitro functional analysis suggested that the variant may impair the dimerization process of PPCA, potentially disrupting proper protein maturation or function and leading to significantly reduced PPCA activity. Exome sequencing did not reveal any variants in other genes associated with primary immunodeficiencies. To date, our cases represent the first reported patients with GS and T-cell defects. Our study broadened the clinical and genotype spectrum of this rare disease.

Galactosialidosis (GS, OMIM #256540) is a rare metabolic disorder resulting from mutations in the protective protein/cathepsin A (PPCA) or CTSA gene, which is characterized by malfunction of the lysosomal glycoprotein degradation and subsequent intra-lysosomal accumulation of sialyloligosaccharides and glycopeptides. It follows an autosomal recessive inheritance pattern. This systemic disease is characterized by typical clinical features such as short stature, coarse facial features, vertebral deformities, gastrointestinal manifestations, particularly hepatosplenomegaly, cardiac abnormalities, hearing loss, and macular cherry-red spots. GS is classified into three subtypes based on the age of onset and presenting symptoms. The three types include the early infantile (EI) form, which is the most severe; the late infantile form; and the juvenile/adult form. Here, we present three newly diagnosed cases of late-infantile GS in Bahraini patients, all sharing the same previously reported homozygous mutation in the CTSA gene (c.607C>A, p.Pro203Thr), confirmed by targeted mutation analysis. This mutation has been identified in nine Bahraini patients, reflecting a founder effect in the Bahraini population. All three patients presented with coarse facial features, short stature, and poor vision, alongside skeletal deformities. Patient 1 had significant bilateral hip osteoarthritis, while Patient 2. showed lumbar lordosis and extensive bilateral hip avascular necrosis. Patient 3 presented with thoracolumbar levoscoliosis and kyphoscoliosis. Additionally, in Patient 1 and Patient 2 cardiac manifestations were noted, including valvular heart disease. Patient 3 had mild left ventricular hypertrophy (LVH), aortic regurgitation, and mitral regurgitation, along with diffuse angiokeratomas. All patients are currently receiving supportive care and management. This case report highlights the importance of early diagnosis and multidisciplinary care of patients with GS.

Hydrops fetalis is an abnormal accumulation of fluid in two or more foetal compartments which is easily detected using prenatal ultrasonography. It can be categorised into immune and non-immune. The non-immune hydrops can result from various aetiologies, including cardiovascular, respiratory, genitourinary infections, chromosomal anomalies and metabolic causes. The metabolic causes, including lysosomal storage disorders (LSD), are increasingly being recognised as the causes of non-immune hydrops. The hydrops fetalis associated with metabolic disorders is usually severe with huge ascites, hepatosplenomegaly, thick skin, renal abnormalities, increased nuchal translucency, renal abnormalities and skeletal deformities. In this report, we describe a case of LSD, that is, galactosialidosis presenting as non-immune hydrops and its diagnosis. In utero diagnosis of the disorder without an index case is challenging. The definitive diagnosis is important for planning and management of future conceptions.