A novel and a known mutation in LSS gene associated with hypotrichosis 14 in a Chinese family

Novel LSS variants in alopecia and intellectual disability syndrome: New case report and clinical spectrum of LSS-related rare disease traits

Pathogenic biallelic variants in LSS are associated with three Mendelian rare disease traits including congenital cataract type 44, autosomal recessive hypotrichosis type 14, and alopecia-intellectual disability syndrome type 4 (APMR4). We performed trio research exome sequencing on a family with a four-year-old male with global developmental delay, epilepsy and striking alopecia, and identified novel compound heterozygous LSS splice site (c.14+2T>C) and missense (c.1357 G>A; p.V453L) variant alleles. Rare features associated with APMR4 such as cryptorchidism, micropenis, mild cortical brain atrophy and thin corpus callosum were detected. Previously unreported APMR4 findings including cerebellar involvement in the form of unsteady ataxic gait, small vermis with prominent folia, were noted. A review of all reported variants to date in 29 families with LSS-related phenotypes showed an emerging genotype-phenotype correlation. Our report potentially expands LSS-related phenotypic spectrum and highlights the importance of performing brain imaging in LSS-related conditions.

A novel homozygous mutation in LSS gene possibly causes hypotrichosis simplex in two siblings of a Tibetan family from the western Sichuan province of China

Aim: Hypotrichosis simplex (MIM 146520) is a rare form of monogenic hereditary alopecia. Several genes have been identified as being associated with the disease, including LPAR6, LIPH, and DSG4. LSS encoding lanosterol synthase (LSS) has been shown to cause hypotrichosis simplex, but the related mechanisms have not been elucidated to date. This study aims to find mutations in LSS from a Chinese family, among which a 21-year-old male patient and his 9-year-old sister were affected by hypotrichosis simplex. Methods: Dermoscopy and histological analysis were used to examine patients' scalps, while exome sequencing was used to find the mutations in LSS. Results: The hair loss was only detected on the scalp of the proband and his sister, while other ectodermal structures were normal with no systemic abnormalities. Further, the exome sequencing identified a new homozygous mutation NM_002340.6 (LSS_v001):c.812T>C (p.(Ile271Thr)) in the LSS gene of the proband, which was also found in his sister. In addition, a heterozygous mutation of LSS was found in their asymptomatic parents. Finally, the possible protein structure of the mutational LSS was predicted. Conclusion: The hypotrichosis simplex reported here could be an autosomal recessive disease in this family. The mutation on LSS might reduce the enzyme activity of LSS, thus leading to the disease.

Novel mutations in Chinese hypotrichosis simplex patients associated with LSS gene

Hypotrichosis simplex (HS) is a rare form of hereditary alopecia caused by a variety of genetic mutations. Currently, only four studies regarding LSS-related HS have been reported. In this study, we try to make a definite diagnosis in two unrelated Chinese families with three pediatric patients clinically suspected of HS. Whole-exome sequencing (WES) was performed for these two families to reveal the pathogenic mutation. WES revealed two different compound heterozygous mutations in LSS in two probands that confirmed the diagnosis, including three novel mutations. In this paper, we describe a new accompanying phenotype of teeth dysplasia in a HS patient. Moreover, we provide a review of all reported LSS mutation-related patients and infer some potential genotype-phenotype correlations for the first time.