H syndrome, also known as Histiocytosis-lymphadenopathy plus syndrome or PHID, is a rare genetic condition caused by mutations in the SLC29A3 gene which encode the human equilibrative nucleoside transporter (hENT3) protein.Moynihan L M, Bundey SE, Heath D, Jones EL, McHale DP, Mueller RF, Markham, AF, Lench NJ (1998) Autozygosity mapping, to chromosome 11q25, of a rare autosomal recessive syndrome causing histiocytosis, joint contractures, and sensorineural deafness. Am J Hum Genet 62: 1123-1128 It is also known as Faisalabad histiocytosis, familial Rosai-Dorfman disease, sinus histiocytosis with massive lymphadenopathy and pigmented hypertrichosis with insulin-dependent diabetes mellitus syndrome.

Presentation

This syndrome has a number of different clinical features many of which start with the letter 'H' giving rise to the name of the syndrome. These features include *

Hyperpigmentation Hyperpigmentation, also known as the dark spots or circles on the skin, is the darkening of an area of Human skin, skin or nail (anatomy), nails caused by increased melanin. Causes Hyperpigmentation can be caused by sun damage, inflammation, or ...

Hypertrichosis Hypertrichosis (sometimes known as werewolf syndrome) is an abnormal amount of hair growth over the body. The two distinct types of hypertrichosis are generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, w ...

Hepatosplenomegaly Hepatosplenomegaly (commonly abbreviated HSM) is the simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly). Hepatosplenomegaly can occur as the result of acute viral hepatitis, infectious mononucleosis, and his ...

* Hearing loss * Heart anomalies *

Hypogonadism Hypogonadism means diminished functional activity of the human gonad, gonads—the testicles or the ovary, ovaries—that may result in diminished biosynthesis, production of sex hormones. Low androgen (e.g., testosterone) levels are referred t ...

* Low height (short stature) *

Hyperglycemia Hyperglycemia is a condition where unusually high amount of glucose is present in blood. It is defined as blood glucose level exceeding 6.9 mmol/L (125 mg/dL) after fasting for 8 hours or 10 mmol/L (180 mg/dL) 2 hours after eating. Blood gluc ...

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

Hallux valgus A bunion, also known as hallux valgus, is a deformity of the MTP joint connecting the big toe to the foot. The big toe often bends towards the other toes and the joint becomes red and painful. The onset of bunions is typically gradual. Compli ...

/flexion contractures

Exophthalmos Exophthalmos (also called exophthalmus, exophthalmia, proptosis, or exorbitism) is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral (as is often seen in Graves' disease) or unilateral (as is often seen in ...

malabsorption Malabsorption is a state arising from abnormality in absorption of food nutrients across the gastrointestinal (GI) tract. Impairment can be of single or multiple nutrients depending on the abnormality. This may lead to malnutrition and a varie ...

and renal anomalies have also been reported.

Genetics

The SLC29A3 gene is located on the long arm of chromosome 10 (10q22).The causative gene was identified in 2010.Morgan NV, Morris MR, Cangul H, Gleeson D, Straatman-Iwanowska A, Davies N, Keenan S, Pasha S, Rahman F, Gentle D, Vreeswijk MPG, Devilee P, and 10 others. Mutations in SLC29A3, encoding an equilibrative nucleoside transporter ENT3, cause a familial histiocytosis syndrome (Faisalabad histiocytosis) and familial Rosai-Dorfman disease. PLoS Genet. 6: e1000833

Pathogenesis

This is not understood at present.

Diagnosis

Management

There is no curative treatment for this condition at present. Management is directed to the clinical features.

History

This condition was first described in 1998.Moynihan L M, Bundey SE, Heath D, Jones EL, McHale DP, Mueller RF, Markham, AF, Lench NJ (1998) Autozygosity mapping, to chromosome 11q25, of a rare autosomal recessive syndrome causing histiocytosis, joint contractures, and sensorineural deafness. Am J Hum Genet 62: 1123-1128

References

External links

{{DEFAULTSORT:H syndrome Autosomal recessive disorders Genetic syndromes Rare syndromes