<unk>  - this boy has an infant brother and maternal uncle with the same affliction The STS gene is located on the<unk>  chromosome at band<unk> p22.3. Thus, the syndrome is an<unk><unk>  condition, and it affects males and females differently. The 23rd pair of chromosomes is typically termed the "sex chromosomes". Females have two<unk>  chromosomes and males have one<unk>  and one Y chromosome. Therefore, in normal individuals, males carry a single copy of the STS gene and females carry two copies. This gene partially escapes<unk> -inactivation and females normally express higher amounts of the STS enzyme than males.<unk>  can occur through new deletions or mutations of the STS gene but is more commonly inherited from a carrier mother. A hemizygous deletion or mutation of the STS gene in a male results in complete absence of enzyme activity, while a female carrier of a mutation or deletion is heterozygous and still has a normal copy of the STS gene. Female carriers of an STS deletion or mutation still express the STS enzyme, although with decreased enzyme activity. For this reason,<unk>  most commonly affects males, although individuals with numeric abnormalities of the sex chromosomes (45,X and 47,XXY) who also carry STS deletions or mutations would be exceptions to this rule. In addition, a female could be affected if she were the offspring of an affected male and a carrier female and inherited a deletion or mutation of the STS gene on both<unk>  chromosomes. Genetic counseling issues Since the majority of cases appear to occur through transmission of an STS deletion from a carrier mother, enzyme testing or DNA testing should be performed in the mother of any newly diagnosed simplex case (i.e. the first case in a family). In the case of an extended family with many affected individuals, carrier status can often be assigned based on pedigree analysis. * Males with<unk>  will transmit the<unk>  chromosome harboring the STS deletion or mutation to each of his female offspring, who will therefore be an obligate carrier. However, all male offspring will be unaffected, since they receive their father's Y chromosome. * Female carriers of an STS deletion or mutation have a 50% chance with each pregnancy of transmitting it to an offspring. Thus, each male offspring has a 50% chance of being affected by<unk> , while each female offspring has a 50% chance of being a carrier for this condition. Any individual that inherits the mother's normal copy of the STS gene will be unaffected and will have an extremely low chance of having a child affected with this condition. Due to random segregation of the chromosomes during gametogenesis, each pregnancy will be subject to the same probabilities, regardless of the number of previously affected or unaffected offspring. The above recurrence risks are based on the assumption that an affected male or carrier female will have children with an unaffected or non-carrier individual. The risks of having affected offspring would clearly increase in the case of a union between a male with<unk>  and a carrier female. Physiology/biochemistry DHEA sulfate The STS enzyme (EC 3.1.6.2), also referred to as Arylsulfatase C, is expressed throughout the body, with highest expression in the skin, liver, lymph nodes, and placenta, and lower expression in breast tissue and brain STS catalyzes the hydrolysis of sulfated steroids, such as estrone sulfate and dehydroepiandrosterone sulfate (DHEAS), to non-sulfated steroids estradiol and androstenediol, respectively. Prenatally, the enzyme is involved in placental estrogen production. The enzyme is also involved in adrenal steroid production as well as conversion of sulfated steroids in other tissues. There seems to be a particularly important role for the enzyme in skin. Deficiency of the enzyme leads to the characteristic dry and scaly skin seen in<unk> . Recent research indicates that the skin abnormalities seen in<unk>  may be due to accumulation of cholesterol sulfate in the outer epidermis, leading to abnormal barrier function and corneocyte retention.
X-linked ichthyosis
Keratoderma
Poikiloderma
Dyskeratosis congenita
Halogenoderma
Photodermatosis
Chyloderma
Bromoderma