Case report of holocarboxylase synthetase deficiency (late-onset) in 2 Chinese patients

[Holocarboxylase synthetase deficiency induced by HLCS gene mutations: a rare disease study]

A boy, aged 16 months, attended the hospital due to head and facial erythema for 15 months and vulva erythema for 10 months with aggravation for 5 days. The boy developed perioral and periocular erythema in the neonatal period and had erythema and papules with desquamation and erosion in the neck, armpit, and trigone of vulva in infancy. Blood gas analysis showed metabolic acidosis; the analysis of amino acid and acylcarnitine profiles for inherited metabolic diseases and the analysis of organic acid in urine suggested multiple carboxylase deficiency; genetic testing showed a homozygous mutation of c.1522C>T(p.R508W) in the HLCS gene. Finally the boy was diagnosed with holocarboxylase synthetase deficiency and achieved a good clinical outcome after oral biotin treatment. This article analyzes the clinical data of a child with holocarboxylase synthetase deficiency and summarizes the etiology, diagnosis, and treatment of this child, so as to provide ideas for clinicians to diagnose this rare disease.

Clinical, biochemical, and genetic analysis of 28 Chinese patients with holocarboxylase synthetase deficiency

BACKGROUND

This study aimed to describe the clinical, biochemical, and molecular characteristics of Chinese patients with holocarboxylase synthetase (HLCS) deficiency, and to investigate the mutation spectrum of HCLS deficiency as well as their potential correlation with phenotype.

METHODS

A total of 28 patients with HLCS deficiency were enrolled between 2006 and 2021. Clinical and laboratory data were reviewed retrospectively from medical records.

RESULTS

Among the 28 patients, six patients underwent newborn screening, of which only one was missed. Therefore, 23 patients were diagnosed because of disease onset. Among all the patients, 24 showed varying degrees of symptoms such as rash, vomiting, seizures, and drowsiness, while only four cases remained asymptomatic nowadays. The concentration of 3-hydroxyisovalerylcarnitine (C5-OH) in blood and pyruvate, 3-hydroxypropionate, methylcitric acid, 3-hydroxyvaleric acid, 3-methylcrotonylglycine in urine were increased greatly among affected individuals. After prompt supplement of biotin, both the clinical and biochemical symptoms were dramatically resolved and nearly all patients developed normal intelligence and physique on follow-up. DNA sequencing revealed 12 known and 6 novel variants in the HLCS gene of patients. Among them, the variant of c.1522C > T was the most common.

CONCLUSIONS

Our findings expanded the spectrum of phenotypes and genotypes for HLCS deficiency in Chinese populations and suggested that with timely biotin therapy, patients with HLCS deficiency showed low mortality and optimistic prognosis. Newborn screening is crucial for early diagnosis, treatment, and long-term outcomes.

Atopic Dermatitis-like Genodermatosis: Disease Diagnosis and Management

Eczema is a classical characteristic not only in atopic dermatitis but also in various genodermatosis. Patients suffering from primary immunodeficiency diseases such as hyper-immunoglobulin E syndromes, Wiskott-Aldrich syndrome, immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, STAT5B deficiency, Omenn syndrome, atypical complete DiGeorge syndrome; metabolic disorders such as acrodermatitis enteropathy, multiple carboxylase deficiency, prolidase deficiency; and other rare syndromes like severe dermatitis, multiple allergies and metabolic wasting syndrome, Netherton syndrome, and peeling skin syndrome frequently perform with eczema-like lesions. These genodermatosis may be misguided in the context of eczematous phenotype. Misdiagnosis of severe disorders unavoidably affects appropriate treatment and leads to irreversible outcomes for patients, which underlines the importance of molecular diagnosis and genetic analysis. Here we conclude clinical manifestations, molecular mechanism, diagnosis and management of several eczema-related genodermatosis and provide accessible advice to physicians.