Expanding on the phenotypic spectrum of Woodhouse‐Sakati syndrome due to founder pathogenic variant in DCAF17: Report of 58 additional patients from Qatar and literature review

Woodhouse‐Sakati syndrome (WSS) is a rare autosomal recessive neuroendocrine and ectodermal disorder caused by variants in the DCAF17 gene. In Qatar, the c.436delC variant has been reported as a possible founder pathogenic variant with striking phenotypic heterogeneity. In this retrospective study, we report on the clinical and molecular characteristics of additional 58 additional Qatari patients with WSS and compare them to international counterparts' findings. A total of 58 patients with WSS from 32 consanguineous families were identified. Ectodermal and endocrine (primary hypogonadism) manifestations were the most common presentations (100%), followed by diabetes mellitus (46%) and hypothyroidism (36%). Neurological manifestations were overlapping among patients with intellectual disability (ID) being the most common (75%), followed by sensorineural hearing loss (43%) and both ID and aggressive behavior (10%). Distinctive facial features were noted in all patients and extrapyramidal manifestations were uncommon (8.6%). This study is the largest to date on Qatari patients with WSS and highlights the high incidence and clinical heterogeneity of WSS in Qatar due to a founder variant c.436delC in the DCAF17 gene. Early suspicion of WSS among Qatari patients with hypogonadism and ID, even in the absence of other manifestations, would shorten the diagnostic odyssey, guide early and appropriate management, and avoid potential complications.


| INTRODUCTION
Woodhouse-Sakati syndrome (WSS) (OMIM 241080) is a rare autosomal recessive multisystem disorder characterized by hypogonadism, diabetes mellitus, alopecia, intellectual disability, and deafness. It was initially described by Woodhouse and Sakati in the mid of 1983 (Agopiantz et al., 2014;Woodhouse & Sakati, 1983b). As of today, 32 families with a total of 76 affected individuals have been reported, mainly from the Middle East, with a possible founder pathogenic variant c.436delC in the DCAF17 gene (S. A. Bohlega & Alkuraya, 2016).
WSS is known for its clinical heterogeneity even among members of the same family, which leads to challenges and delays in reaching a diagnosis (S. A. Bohlega & Alkuraya, 2016). A study of the clinical features of 76 individuals with WSS from 32 families (23 were molecularly diagnosed) showed that almost all cases have endocrine findings such as hypogonadism at the time of puberty and progressive childhood-onset and adolescent hair thinning that frequently develops to alopecia in adulthood. Almost all WSS cases have low insulin-like growth factor 1 (IGF-1), around two-thirds have adolescent-onset to young adult-onset diabetes mellitus, and more than a quarter have hypothyroidism. From a neurological point of view, more than half of the cases have progressive extrapyramidal movements such as dystonic spasms with dystonic posturing, dysarthria, and dysphagia, moderate bilateral post-lingual sensorineural hearing loss, and mild intellectual disability (Ben-Omran et al., 2011;Gül et al., 2000;Habib et al., 2011;Koshy et al., 2008;Matsuno et al., 2017;Medica et al., 2007;Steindl et al., 2010).
At the genetic level, the DCAF17 gene, located on chromosome 2q22.3-q35 and formerly known as C2orf37, is responsible for WSS.
The DCAF17 gene was first documented in 2008 and nine pathogenic variants have been described in the literature to date (Alazami et al., 2008).
In 2011, we reported seven Qatari patients with a milder phenotype of WSS from two consanguineous families from a highly endogamous tribe. These patients showed intrafamilial phenotypic variability with the spectrum of clinical characteristics previously seen in WSS but with no evidence of extrapyramidal symptoms. That study also suggested that WSS is common in Qatar and the Arab region due to a possible founder effect in the DCAF17 c.436delC variant (Ben-Omran et al., 2011). The current retrospective study was carried out to describe and delineate the diversity of clinical phenotypes among 58 patients with WSS residing in Qatar who carry the same founder pathogenic variant c.436delC in the DCAF17 gene and to compare them with international findings from both a clinical and a molecular perspective.

| METHODS
A single-center study (Ault and Pediatric Medical Genetics, Hamad Medical Corporation, Doha, Qatar) was performed between October 1, 2020, and October 1, 2021, in patients with WSS. Detailed clinical and molecular data were retrospectively collected.
Information collected for each patient included: demographic data, clinical manifestations based on the most commonly involved system such as endocrinological, neurological, and ectodermal. In addition, molecular findings, family history, and consanguinity were collected.
An extensive review of the literature using the PubMed database and Google Scholar was performed. A full list of cases was recorded by searching PubMed and Google Scholar with the following keywords: Woodhouse-Sakati, C2orf37, DCAF17, hypogonadism and alopecia, hypogonadism and dystonia, and hypogonadism and IGF1. All patients clinically diagnosed with WSS were included in the review of this study. Cases who did not meet the inclusion criteria were not eligible in the review.

| Variant analysis
The patients' genomic DNA was extracted. Exon 4 of the DCAF17 gene was PCR amplified and capillary sequencing was performed in the clinical setting for all patients except one who presented with neck dystonia and for whom whole exome sequencing (WES) was performed. Bi-directional sequence was assembled, aligned to reference gene sequences based on human genome build GRCh37/UCSC hg19, and analyzed for known familial sequence variant(s). Sequence alterations were reported according to the Human Genome Variation Society (HGVS) nomenclature guidelines.
Common haplotype analysis on this variant was also conducted to prove the founder effect as described before (Burns et al., 2018).

| Statistical analysis
Descriptive statistics in the form of mean, range, and frequency, with percentages, were calculated.

| Demographic features and clinical characteristics
We studied 58 patients (24 males, 34 females, mean and range of current age 20, 8-37 years) with WSS from 32 families. The mean and range of age at diagnosis were 14.2 and 3-31 years, respectively. A total of 29 patients were children (0 to ≤14 years), 14 were adolescents (14 to ≤18 years), and 15 were adults (19-59 years).
All patients were of Qatari ethnic background with 100% of the families reporting parental consanguinity and 50% reporting a positive family history of similar illness (Table 1).

| Clinical characteristics and age of onset
All of the 58 (100%) patients had endocrine manifestations in the form of hypogonadism, 27 (46%) had diabetes mellitus, and 21 (36%) had hypothyroidism. The endocrine findings such as hypogonadism and diabetes mellitus were found to be evident at puberty, that is, from adolescent-onset to young adult-onset (Tables 2-4).
Ectodermal manifestations were also documented in 58 (100%) patients who all had alopecia while one (1.7%) had anodontia. A progressive childhood-onset hair thinning often progressed to alopecia in adulthood (Tables 2-4).
In addition, neurological involvements were also documented. ID was found in 44 (75%) patients, sensorineural hearing loss was found in 25 (43%) patients, and six (10%) had both ID and aggressive behavior.
The onset of neurological manifestations was found to be in childhood (Tables 2-4). A total of 20 patients had brain MRI, of which 11 (55%) had normal studies, five (25%) showed a picture of iron deposition within the globus pallidus and the substantia nigra, two (10%) had an atrophied anterior pituitary, and two (10%) had nonspecific hyperintensity in the form of bilateral periventricular and subcortical white matter changes (WMCs).
Distinctive facial features were noted in all patients: long triangular face, prominent nasal bridge, widely spaced eyes, and sparse eyebrows. The onset of facial deformities was found to be in childhood (Tables 2-4).

| Literature findings
A total of 122 WSS cases from 53 families have been described in the literature so far from different populations around the world.
Molecular diagnoses have been confirmed in 114 WSS cases. The first WSS cases were clinically described in 1973 in Italy (Crandall et al., 1973). Later, several clinically similar cases were reported around the world. A total of eight WSS cases were clinically described in Lebanon in 1979 (Slti & Salem, 1979) and six WSS cases from two different families were clinically diagnosed in Saudi Arabia in 1983 (Woodhouse & Sakati, 1983). In 1985, five more WSS cases were clinically diagnosed in Kuwait (Al-Awadi et al., 1985). From the early 1990s to the beginning of the 21st century, a total of nine WSS cases were further clinically described: four, two, one, and two WSS cases were clinically diagnosed in Myanmar, Belgium, Turkey, and Lebanon, respectively (Devriendt et al., 1996;Gül et al., 2000;Mégarbané et al., 2003;Oerter et al., 1992) (Table S1).
After the discovery of the DCAF17 gene as the gene responsible for WSS, different pathogenic variants were characterized in the DCAF17 gene and the molecular diagnosis of these pathogenic variants was confirmed in almost all the WSS cases that were subsequently reported.
Further, different pathogenic variants in the DCAF17 gene were reported in different populations. One WSS case was diagnosed with a c. 50delC in Slovenia (Medica et al., 2007).
A couple WSS cases were diagnosed with a c.1091+6T>G pathogenic variant in a Middle Eastern family and a Portuguese family (Kurnaz et al., 2019;Louro et al., 2019).
In addition, two different types of pathogenic variants in the DCAF17 gene were additionally reported in the Turkish population: two cases with a c.127-1G>C pathogenic variant (Gurbuz et al., 2018), and one case with a c.270dup pathogenic variant (Sendur et al., 2019).  (Table 5 and Figure 1).

| Molecular findings
To date, 19 pathogenic variants are identified in DCAF17 gene, including frameshift and nonsense pathogenic variants as well as splice-site ablations. All these pathogenic variants result in a truncated protein (  NA 1 (33%) Y 6 (100%) NR c.436delC Al-Semari and Bohlega (2007), Alazami et al. (2008) c.50delC Medica et al. (2007), Alazami et al. (2008) Middle Eastern Alazami et al. (2008), Schneider and Bhatia (2008) T A B L E 5 (Continued)   and β that are expressed in equivalent abundance. Both α and β WSS protein were found to be ubiquitously expressed in all tissues with relatively higher expression in the brain, liver, and skin (Alazami et al., 2008). Interestingly, a novel third nuclear isoform of 80-kDa has been recently described and needs further investigation to understand its role (Blocka, 2018 (2007) Japanese c.796 G>T NA Matsuno et al. (2017) evidence presented in this study regarding the high incidence, founder effect, and clinical heterogeneity of WSS in Qatar, it is important to raise awareness on the signs and symptoms of WSS and its clinical heterogeneity in order to reduce the diagnostic odyssey of patients and provide prompt interventions and management. In addition, we recommend that WSS be added in large screening programs such as premarital screening in Qatar in order to reduce the incidence of the disease. This may be achieved through the identification of carriers and at-risk couples and the provision of genetic counseling and guidance regarding reproductive options.
This retrospective study has one limitation: it could not characterize the rate of progression of the disease because all of the medical charts of WSS patients were reviewed at variable clinical stages of the disease.

| CONCLUSIONS
WSS is a multisystem disease with diverse clinical presentations.
Interfamilial and intrafamilial phenotypic variability is present among patients with the same pathogenic variants, which could be due to potential role of both genetic or environmental modifying factors and interactions. We conclude that targeted testing for the DCAF17 founder variant c.436delC should be included in the clinical workup of patients with hypogonadism and intellectual disability, even in the absence of other typical syndromic characteristics, especially in individuals of Qatari and Middle Eastern ancestry. Our study also recommends having an early detection strategy through family screening or by adding WSS to the premarital screening program to reduce the incidence of the disease or at least to allow for early multidisciplinary management to avoid potential complications.
This report also highlights the importance of early suspicion of WSS among individuals of Middle Eastern ancestry and especially of Qatari origin with hypogonadism and intellectual disability, even when other typical syndromic characteristics are absent, which could shorten the diagnostic odyssey, guide early and appropriate multidisciplinary management, and prevent potential complications.