An X-linked recessive variety of ichthyosis vulgaris different from the X-linked ichthyosis of Wells and Kerr

Pedigree analysis of ichthyosiz vulgaris in an extensive North German kindred revealed X-linked recessive inheritance. Only males were affected; heterozygous females had no sign of this derma-tosis. Clinically and histologically, the disease resembled the autosomal dominant form. The differential diagnosis between this X-linked recessive ichthyosis vulgaris, ichthyosiz congenita mitis, and X-linked ichthyosis of the Wells-Kerr type is discussed. We conclude from our qtudy that ichthyosis vulgariz is genetically heterogeneous.     

An X-linked recessive variety of ichthyosis vulgaris different from the X-linked ichthyosis of Wells and Kerr

Pedigree analysis of ichthyosis vulgaris in an extensive North German kindred revealed X-linked recessive inheritance. Only males were affected; heterozygous females had no sign of this dermatosis. Clinically and histologically, the disease resembled the autosomal dominant form. The differential diagnosis between this X-linked recessive ichthyosis vulgaris, ichthyosis congenita mitis, and X-linked ichthyosis of the Wells-Kerr type is discussed. We conclude from our study that ichthyosis vulgaris is genetically heterogeneous.     

X-linked ichthyosis in Mexico: High frequency of deletions in the steroid sulfatase encoding gene

The present study analyzes the frequency of molecular deletions in the steroid sulfatase (STS) encoding gene in a sample of 50 Mexican subjects with biochemical diagnosis of X-linked ichthyosis (XLI). To establish the correct diagnosis, STS activity was determined in leukocytes using 7-³H-dehydroepiandrosterone sulfate as the substrate. No amplification of the 3′ and 5′ ends of the STS gene by PCR was detected in the DNA of 49 patients, whereas only one sample of 50 presented a normal amplification. This report shows a very high frequency of deletions in the human STS encoding gene in a representative sample of the Mexican population, and it defines the characteristics of XLI in patients whose STS gene has a complete deletion as a major molecular defect. Am. J. Med. Genet. 72:415–416, 1997. © 1997 Wiley-Liss, Inc.     

Carrier identification by FISH analysis in isolated cases of X-linked ichthyosis

X-linked ichthyosis (XLI) is an inborn error of metabolism due to steroid sulfatase (STS) deficiency. STS assay and FISH are useful in diagnosing carrier status of XLI. Biochemical analysis appears to indicate that most sporadic cases are inherited. Since this method does not seem to be completely reliable in recognizing XLI-carriers, the aim of the present study was to corroborate by FISH whether or not most sporadic cases of XLI had de novo mutations. XLI patients were classified through STS assay and PCR amplification of 5'-3' ends of the STS gene. XLI patients had undetectable levels of STS activity and complete deletion of the STS gene. Patients' mothers were studied through STS assay and FISH. Nine out of 12 mothers presented an STS activity compatible with XLI-carrier state. These mothers also had only one copy of the STS gene, indicating that they carry the primary gene defect. One mother had normal STS activity but only one copy of the STS gene. This data corroborated that most sporadic cases do not represent de novo mutations, and that FISH must be included in the analysis of mothers of sporadic cases when they present with normal STS activity, in order to correctly diagnose the XLI carrier state.     

X-linked ichthyosis and X-linked placental sulfatase deficiency: a disease entity. Histochemical observations.

The combined occurrence of X-linked steroid sulfatase deficiency of the placenta and X-linked ichthyosis is reported in 6 unrelated boys. Placental steroid sulfatase deficiency was diagnosed on the basis of a very low total estrogen excretion (6 cases), verified prenatally by the dehydroepiandrosterone sulfate (DHEAS) loading test in 4 cases and postnatally by clinical investigations (6 cases) and by biochemical investigations (5 cases). In addition, microsomal arylsulfatase C (MAS) could not be detected in the placental homogenate of the five cases investigated. Lysosomal arylsulfatases were within the normal range. All boys developed well except for X-linked ichthyosis. In the 5 cases investigated the skin biopsy showed the same MAS deficiency histochemically in the granular layer of the epidermis as in the trophoblast cells. The same holds true for the skin of carriers. Steroid sulfatase activity of cultured skin fibroblasts from the boys was almost nil (3 cases). The histochemical technique offers a practical approach in the scientific investigation of keratotic conditions.     

X-linked ichthyosis, bilateral cryptorchidism, hypogenitalism and mental retardation in two siblings

Two brothers showed ichthyosis, bilateral cryptorchidism, hypogenitalism and mental retardation. In addition, the younger brother had short stature associated with disorders of secretions of insulin, ACTH and GH. This is the third reported case of the syndrome of ichthyosis and hypogonadism.     

PCR diagnosis of X-linked ichthyosis: identification of a novel mutation (E560P) of the steroid sulfatase gene

X-linked ichthyosis (XLI) is an inherited skin disorder due to deficiency of steroid sulfatase (STS) activity. XLI has been diagnosed by assaying STS activity in placenta or lymphocytes of patients after birth. Most patients have a large deletion of the STS gene, generated by inaccurate recombination at the STS locus. However, point mutations in the STS gene have been reported in some patients with complete STS deficiency. In a new case of STS deficiency, we identified an STS missense mutation, Glu560Pro or E560P. This new point mutation suggests that the C-terminal region of the STS enzyme is important for STS enzymatic function. Hum Mutat 15:296, 2000.     

Steroid sulfatase deficiency in Japanese patients: Characterization of X-linked ichthyosis by using polymerase chain reaction

Summary X-Linked ichthyosis (XLI) due to deficiency of steroid sulfatase (STS) of which gene consists of 10 exons is an inherited skin disorder. The gene, mRNA and protein of STS were examined in six Japanese patients with XLI. Neither the mRNA nor the enzyme protein was detected in a patient. The results of Southern analysis using STS cDNA as a probe indicated that all the patients examined exhibited large deletions of the STS gene. When exon 1 and the exon 10 of the STS gene were amplified by polymerase chain reaction using patients' genomic DNA as templates, no product was detected in all the patients examined. These observations suggest that most XLI in Japanese patients is caused by an extensive deletion of the STS gene as was demonstrated in Caucasian patients. The PCR method in the present study is useful for the diagnosis of XLI in prenatal and postnatal subjects.     

Analysis of an interstitial deletion in a patient with Kallmann syndrome, X-linked ichthyosis and mental retardation

Contiguous gene syndromes are an interesting clinical phenomenon, resulting from interstitial or terminal deletions of several adjacent genes. The phenotype results in a combination of two or more monogenic disorders and relates clinical findings to corresponding genotypes. We present the case of a male patient with Kallmann syndrome (KS), X-linked ichthyosis (XLI) and X-linked mental retardation (MRX). He was referred at the age of 15.4 years for delayed puberty and obesity. He had a previous history of pyloric stenosis, bilateral orchidopexy and surgical correction of a pes equinovarus adductus. On physical examination, generalised ichthyosis and hypoplastic external genitalia were found. KS was evident with hypogonadotropic hypogonadism, hyposmia and a hypoplastic anlage of the olfactory tract in magnetic resonance imaging. Lipoprotein electrophoresis, and lack of steroid sulfatase and arylsulfatase-C activity in leucocytes confirmed XLI. DNA investigation established an interstitial deletion in Xp22.3 involving the Kallmann (KAL) gene, the steroid sulfatase (STS) gene and a putative mental retardation locus (MRX). The novel MRX locus maps to a 1-Mb region between DXS1060 and GS1.     

Immunoglobulin heavy chain gene rearrangements in X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) appears to involve a defect in human B lymphocyte differentiation which is manifested at the pre-B cell stage. The defect segregates as an X-linked recessive trait but is not a single genetic entity. IgM-producing B cell clones were established by Epstein-Barr virus transformation of peripheral blood mononuclear cells of patients with the XLA defect linked to the DXS3 and DXS17 chromosomal loci. Individual XLA B cell clones were demonstrated to have rearrangements of the JH regions of both immunoglobulin VH region loci. The rearranged JH regions of the B cell clone ALA 19 were molecularly cloned and their nucleotide sequence was determined. Both JH-associated rearrangements (designated 191 and 192) resulted from the juxtaposition of variable (VH), diversity (D) and joining (JH) segments (VHDJH rearrangements). The 191 rearrangement employed a VH segment belonging to VH subgroup III and a JH4 segment. The 192 rearrangement employed a VHII and a JH6 segment. The D191 and D192 segments encompassed 21 and 28 nucleotides, respectively, and showed little homology to each other or to previously reported human D sequences. Surprisingly, both VHDJH complexes had open reading frames. However, in accord with principles of allelic exclusion, only the 191 allele was detectably expressed in the total RNA of the cell. A possible mechanism for the lack of expression of the 192 allele is discussed. We conclude that the DXS3-DXS17-linked XLA defect does not preclude VH to DJH rearrangements or the expression of VH containing heavy chain molecules.     

The abnormal gene in X-linked lymphoproliferative syndrome.

The gene defect responsible for X-linked lymphoproliferative syndrome, SH2D1A (SH2-domain-containing gene 1A), was recently cloned. This gene encodes a small protein of 128 amino acids containing a single SH2 domain, which is thought to play an important role in signal transduction in activated T cells. The definition of SH2D1A protein function will provide insight into the pathogenesis of fatal Epstein-Barr virus infection, lymphomas, Hodgkins disease, immunodeficiency, aplastic anemia and lymphohistiocytic disorders that characterize the syndrome.