Cutis Laxa, Autosomal Recessive, Type Ib

A number sign (#) is used with this entry because autosomal recessive cutis laxa type IB is caused by homozygous or compound heterozygous mutation in the EFEMP2 gene (604633), also known as FBLN4, on chromosome 11q13.

Description

Autosomal recessive cutis laxa type IB (ARCL1B) is characterized by the presence of severe systemic connective tissue abnormalities, including emphysema, cardiopulmonary insufficiency, birth fractures, arachnodactyly, and fragility of blood vessels. All symptoms refer to disturbed elastic fiber formation (summary by Hoyer et al., 2009).

For a complete phenotypic description and a discussion of genetic heterogeneity of autosomal recessive cutis laxa, see ARCL1A (219100).

Clinical Features

Ades et al. (1996) reported 4 unrelated children, 3 boys and 1 girl, with congenital abnormalities of the great vessels, comprising either single or multiple arterial aneurysms, aortic and/or arterial dilation, and/or vessel tortuosity. The authors noted that each child had a distinct phenotype, but all had in common the rare finding of aneurysms of the aorta and main pulmonary artery. Progression of these abnormalities was clearly evident in the female patient, who had diffuse vessel irregularity and tortuosity involving intraabdominal, intracranial, and extracranial arteries. She presented within the first 2 months of life with airway compression, aneurysm of the ascending aorta with dilatation of the proximal aortic arch and innominate artery, massive dilatation of the pulmonary trunk beyond the pulmonary valve, proximal pulmonary arterial stenosis, and moderate pulmonary regurgitation. After surgical repair of the aortic and pulmonary trunk aneurysms at 2.5 months of age, recurrent episodes of life-threatening respiratory obstruction developed at age 7 months, at which time she was found to have a massive recurrence of aneurysm of the ascending aorta and innominate artery, requiring reoperation at 8 months of age. Cineangiography at 39 months of age showed redundant aortic arch with significant dilation of the pulmonary trunk and proximal right and left branches and a mildly tortuous abdominal aorta with tortuosity and dilation of the major abdominal arteries. Ultrasonography at 4.5 years of age showed marked tortuosity and mild fusiform dilatation of the right common carotid artery, with less marked tortuosity of the left common carotid. Cerebral angiography at 5.5 years showed extreme tortuosity and dilatation of intra- and extracranial arteries. Other features in this patient included prominent eyes, bulbous nasal tip, prominent premaxilla, highly arched palate, micrognathia, generalized mild joint hypermobility, and velvety smooth skin with normal scarring. Histologic examination of tissue from the aorta and pulmonary artery showed a marked disruption of elastic fibers with an increase in deposition of interstitial glycosaminoglycans and marked thickening of the arterial intima. Large elastic fibers were markedly reduced in number and small elastic fibers were highly irregular in distribution. Analysis of dermal fibroblasts from this patient demonstrated that the proportion of collagen forming mature crosslinks was within the normal range, as was the kinetics of crosslink formation.

Baspinar et al. (2005) studied a 3-year-old boy referred for evaluation of a widened mediastinum discovered on routine chest x-ray. The boy had unusually flattened facies with a prominent forehead, depressed nasal bridge, hypertelorism, narrow nostrils, high-arched palate, pectus excavatum, and moderate hypermobility of the joints. CT of the chest revealed a dilated aortic arch; transthoracic echocardiography demonstrated an aneurysmal dilation of the ascending aorta and a high aortic arch with a kink at the isthmus level. The diameters of the aortic valve, aortic root at the sinus Valsalva level, and the ascending aorta were 1.07 cm, 2.8 cm, and 4.3 cm, respectively. Aortography showed an elongated aorta with 2 acute curves, at the arcus aorta and at the diaphragmatic level. Although the boy was asymptomatic, he was placed on beta blocker therapy due to the risk of spontaneous rupture of the ascending aorta. Baspinar et al. (2005) noted that the facial dysmorphism and multiple joint dislocations were suggestive of Larsen syndrome (150250).

Hucthagowder et al. (2006) described a patient with cutis laxa and severe systemic connective tissue abnormalities. The patient, the child of unaffected nonconsanguineous parents of Iraqi descent, was born with multiple fractures at gestational age 36 weeks, after an uneventful pregnancy, although oligohydramnios was reported. Examination at age 9 months revealed generalized cutis laxa with soft, velvety, and transparent skin. Additional observations included hypotonia, emphysema, generalized arterial tortuosity, inguinal and diaphragmatic hernia, joint laxity, and pectus excavatum. Diaphragmatic plication was performed at the age of 10 months. During surgery, both arterial and venous tortuosity, emphysematous and hyperexpanded lungs, and an esophagus not fixed to the posterior chest were observed. The diaphragm contained very little muscle and mainly consisted of pleuroperitoneal membrane. Aortic root aneurysm was diagnosed at the age of 2 years.

Dasouki et al. (2007) reported an infant girl with apparent arachnodactyly, mild cutis laxa, and severe systemic vascular abnormalities that were inoperable and incompatible with life; she died on day 27 of life. Autopsy findings included biventricular hypertrophy and right ventricle dilatation, aneurysmal dilation of the ascending aorta and main branches of pulmonary arteries with dissection of the wall, and intussusception-like telescoping of the inner arterial layer causing severe luminal narrowing of the main branches of the pulmonary arteries. Histopathologic examination of skin, aortic wall, and pulmonary artery revealed that elastic fibers in all 3 tissues were markedly decreased in density, fragmented, and shortened.

Hoyer et al. (2009) reported the third case of cutis laxa due to FBLN4 mutation (604633.0004). The patient was an infant girl who was born of consanguineous Iraqi parents, from a pregnancy remarkable for fetal overgrowth and oligohydramnios, and who died immediately after birth with extreme bradycardia. She exhibited cutis laxa, arachnodactyly of hands and feet with contractures of the third to fifth fingers, medial rotation of feet, spina bifida of the os sacrum, microcephaly, and facial dysmorphism. Autopsy showed collapsed lungs with hypoplastic diaphragm and signs of cervical soft tissue bleeding due to vessel fragility. Histologic examination showed fragmentation of elastic fibers with formation of cystic cavities in the medial layer of the aorta and central lung vessels. Hoyer et al. (2009) stated that this case extended the phenotypic spectrum of FBLN4 mutations to include microcephaly, overgrowth, and arachnodactyly.

ARCL1B, Mappila Type

Kappanayil et al. (2012) reported 22 unrelated infants, members of the Mappila Muslim group from the northern coastal Malabar region of the southern Indian state of Kerala. Eight of these patients had a family history of consanguinity; 4 families had a history of infant death. Patients presented at a median age of 1.5 months with the typical aneurysmal dilatation, elongation, tortuosity, and narrowing of the aorta, pulmonary artery and their branches seen in other patients with ARC1B. The phenotype included a variable combination of cutis laxa (52%), long philtrum with thin vermilion (90%), micrognathia (43%), hypertelorism (57%), prominent eyes (43%), sagging cheeks (43%), long, slender digits (48%), and visible arterial pulsations (38%). Early death (at 4 months of age or less) occurred in 17 of 21 patients homozygous for the same mutation (see MOLECULAR GENETICS). Isthmic hypoplasia in 9 correlated with early death.

Molecular Genetics

Hucthagowder et al. (2006) described a child with cutis laxa caused by homozygosity for a missense mutation (604633.0001) in the EFEMP2 gene (FBLN4).

Dasouki et al. (2007) identified compound heterozygosity for a missense mutation and a 4-bp duplication in the FBLN4 gene (604633.0002 and 604633.0003, respectively) in a patient with cutis laxa, arachnodactyly, and severe systemic vascular abnormalities. Analysis of the FBLN5 (604580) gene showed no mutations. The authors noted overlapping phenotypic similarities to the patient described by Hucthagowder et al. (2006).

In the infant girl with cutis laxa reported by Hoyer et al. (2009), sequencing of the FBLN4 gene revealed a homozygous missense mutation in exon 7 (604633.0004).

Renard et al. (2010) sequenced the FBLN4 gene in 17 patients with prominent cutis laxa but no major cardiovascular findings, who were known to be negative for mutation in the ELN (130160) and FBLN5 genes, but detected no FBLN4 mutations. Analysis of a second cohort of 22 patients who had mild skin involvement but significant cardiovascular features, including arterial tortuosity, stenosis, and aneurysms, and who had previously tested negative for mutation in the SLC2A10 (606145), FBN1 (134797), TGFBR1 (190181), and TGFBR2 (190182) genes, revealed homozygosity or compound heterozygosity for mutations in the FBLN4 gene in 3 patients (604633.0005-604633.0008), 2 of whom had previously been described (Ades et al., 1996; Baspinar et al., 2005). Renard et al. (2010) concluded that patients with recessive FBLN4 mutations are predominantly characterized by aortic aneurysms and arterial tortuosity and stenosis, and stated that these findings confirmed the important role of fibulin-4 in vascular elastic fiber assembly.

Kappanayil et al. (2012) detected homozygosity for a missense mutation in exon 7 of the FBLN4 gene (604633.0009) in 21 of 22 infants from the Mappila community of southern India with characteristic arterial dilatation and tortuosity. One patient was compound heterozygous for this mutation and a de novo missense mutation on the paternal allele. Both mutations occurred in the same conserved calcium-binding EGF domain. Homozygosity was lethal in the majority; 17 of 21 died at a median age of 4 months.