H syndrome (OMIM # 602782), first described in 2008, is a rare autosomal recessive genodermatosis which is multisystemic and is primarily characterized by cutaneous hyperpigmentation, hypertrichosis, hepatosplenomegaly, hearing loss, heart anomalies, hypogonadism, short stature, hyperglycemia (insulin-dependent diabetes mellitus), and hallux valgus/flexion contractures. It is caused by mutations in the solute carrier family 29 (SLC29A3) gene. A 23-year-old female patient who had the characteristic clinical features of H syndrome was referred to our medical genetics outpatient clinic to confirm the clinical diagnosis through molecular testing, to arrange the clinical follow-up and treatment support programme, and to provide the patient with suitable genetic counselling.
Clinical examination was performed. Related tests and imaging methods were planned. All coding exons of SLC29A3 gene were sequenced.
Physical examination revealed cutaneous hyperpigmentation on the body/on lower and upper extremity skin except knees and elbows, bilateral hypertrichosis on lower extremity (proximal), hepatosplenomegaly (splenomegaly), bilateral sensorineural hearing loss, heart anomalies, hyperglycemia (insulin-dependent diabetes mellitus), hallux valgus/flexion contractures (flexion contractures on bilateral hands/feet). Homozygote nonsense mutation causing premature stop codon (p.Y428*) in SLC29A3 gene exon sequencing was detected.
H syndrome is a rare genetic disease which requires multidisciplinary treatment because of its multisystemic involvement. Molecular genetic testing is important to confirm the diagnosis, to provide appropriate genetic counselling and to estimate prenatal diagnosis possibilities for the following pregnancies. As far as we are concerned, there are two more cases reported except ours in Turkey until now. More than 100 patients and 20 mutations in SLC29A3 gene have been described in the world. We find it convenient to present this rarely observed case in order to discuss the clinical findings and the mutation found in our case.