Whole-exome sequencing revealed a novel mutation of the ALMS1 gene in a Chinese family with Alström syndrome: a case report.

BACKGROUND

Alström syndrome (AS) is a rare autosomal recessive disorder that leads to multiple organ fibrosis and failure. Precise diagnosis from the clinical symptoms is challenging due to its highly variabilities and its frequent confusion with other ciliopathies and genetic diseases. Currently, mutations in the ALMS1 gene have been reported as a major cause of AS, thus, it is crucial to focus on the detection and discovery of ALMS1 mutations.

CASE PRESENTATION

We present a case of a 13-year-old Chinese boy weighing 70 kg and standing 168 cm tall. He has two younger brothers. Their parents hail from different ancestral homes in eastern and northern China. The patient's primary clinical findings included visual impairment at the age of four and progressive hearing loss starting at the age of ten. Subsequently, at the age of twelve, the patient developed hyperlipidaemia and hyperinsulinemia. Ultrasonographic findings indicated the presence of gallstones and mild fatty liver. His Body Mass Index (BMI) significantly increased to 25 kg/m (ref: 18.5-23.9 kg/m). Additionally, echocardiography revealed mild mitral and tricuspid regurgitation. Ultimately, Whole Exome Sequencing (WES) identified a new missense mutation in the ALMS1 gene (NG_011690.1 (NM_015120): c.9536G > A (p.R3179Q)). This missense mutation generated an aberrant splicer and disrupted the stability and hydrophobicity of proteins, which preliminarily determined as " likely pathogenic". Therefore, considering all the above symptoms and molecular analysis, we deduced that the patient was diagnosed with AS according to the guidelines. We recommended that he continue wearing glasses and undergo an annual physical examination.

CONCLUSION

In this case report, we report a novel homozygous ALMS1 mutation associated with AS in the Chinese population, which expands the mutation spectrum of ALMS1. Genetic testing indeed should be incorporated into the diagnosis of syndromic deafness, as it can help avoid misdiagnoses of AS. While there is no specific treatment for AS, early diagnosis and intervention can alleviate the progression of some symptoms and improve patients' quality of life.