Patients 2 and 3 are 2 siblings from nonconsanguineous Moroccan parents. They have a sister who is affected by an agenesis of the corpus callosum. Patient 2 was born at term, after an unremarkable gestation, weighing 3290 g. Profuse secretory diarrhea began on the seventh day of life, with ionic disorders and severe dehydration. Parenteral nutrition was immediately started. At present, he is 2 years old and receives parenteral nutrition (110 mL · kg−1 · day−1, 12/24 hours, 7/7 days).
His brother was born at term (birth weight 3570 g) after a gestation marked by a hydramnios and an echogenic bowel at 34 weeks of gestation. Diarrhea began more insidiously and led to malnutrition and ionic disorders only at 6 weeks of life. He is now 1 year old and receives parenteral nutrition daily (110 mL · kg−1 · day−1). The 2 siblings developed an intrahepatic cholestasis with low γ-glutamyl transferase (GGT). Liver biopsies showed centrolobular cholestasis without fibrosis or ductular proliferation.
Histological features of the 2 siblings were similar. At the age of 2 months, duodenum biopsies (Fig. 1B and C, and Supplementary Fig. 1B and C, http://links.lww.com/MPG/A360) revealed a severe villous atrophy in duodenum, accumulation of PAS-staining material at the apex of enterocytes from the surface epithelium and the upper part of the crypts. A mild inflammatory infiltrate of the lamina propria with no increase in intraepithelial lymphocytes and an increased number of mitoses within the crypts was noted. TEM showed heterogeneous lesions of the brush border. Microvilli were shortened (<0.5 μm) and disoriented. No microvillous inclusions were seen but many secretory granules and autophagic vacuoles (Fig. 3A and B). Two MYO5B mutations were found in both siblings in exon 10 (c1222A>T) and 13 (c1582C>T). They lead to amino acid substitutions within the motor part of the protein.
Patient 4 had a heavy medically charged family history: Berger disease in his father, severe deafness in his mother, and epilepsy in 2 brothers and 1 aunt. One of his brothers died in infancy owing to a similar disease (intestinal failure, facial dysmorphy, retinitis pigmentosa, severe epilepsy, cortical atrophy, mental retardation, and failure to thrive). There was no consanguinity in the family. He was born at term, after an unremarkable gestation, weighting 3360 g. Diarrhea began on the fifth day of life, with severe dehydration and parenteral nutrition requirement (160 mL · kg−1 · day−1). He also experienced hypothalamic hamartoma, sensorial deficiencies (blindness, optical atrophy, nystagmus, unilateral deafness), and severe mental retardation. At present, he is 12 years old and receives parenteral nutrition (65 mL · kg−1 · day−1 every day). He has mild growth retardation (size at −2 SD) and nephrocalcinosis.
MVID was diagnosed on the first duodenal biopsy when he was 22 days old (Fig. 1D and E and Supplementary Figs. 1D and E, http://links.lww.com/MPG/A360). Microscopic observations revealed mild partial villous atrophy. PAS-positive material accumulated at the luminal pole of upper crypt enterocytes whereas surface enterocytes were less affected. CD10—which is normally expressed at the surface of the brush border—also accumulated in the cytoplasm of the enterocytes. There was a mild inflammatory infiltrate within the lamina propria, but no increase in intraepithelial lymphocytes. Colonic biopsies were normal. TEM showed rare microvilli and vacuolization of the cytoplasm. We failed to detect MYO5B mutations (30–33).
Patient 5 was born at 40 weeks of gestation from nonconsanguineous French parents after a pregnancy marked by an intrauterine failure to thrive. He weighed 2380 g. Diarrhea began in the neonatal period in the context of a Staphylococcus aureus and an Escherichia coli K1 sepsis and severe ionic disorders. Parenteral nutrition was quickly started but could be stopped at 4 months and replaced by enteral nutrition. He presented with cholestasis with low GGT and pruritus, which were only partially improved by ursodesoxycolic acid supplementation. Liver biopsy showed mild intrahepatocyte cholestasis without biliary paucity. He had a polymalformative syndrome with facial dysmorphy, blindness (right anophthalmia, iris coloboma, left cataract, optic nerve atrophy), dolichocephaly, laryngeal palsy, deafness, brainstem hypoplasia, and mental retardation. A high-resolution karyotype was normal. Otherwise, he experienced cow's-milk–protein allergy and gastroesophagal reflux disease. At present, he is 13 years old and has a gastrostomy for nocturnal enteral nutrition (60 mL · kg−1 · day−1). He has growth retardation (height −3 SD).
Patient 5 underwent 3 duodenal biopsies showing discrete partial villous atrophy. PAS staining showed focal accumulation at the luminal pole of the enterocytes of the low villous region without inflammatory infiltrate or increased intraepithelial lymphocyte count (Fig. 1F–G and Supplementary Fig. 1F–H, http://links.lww.com/MPG/A360). TEM showed rare and isolated microvilli, with filamentous core rootlets under the terminal web, possible microvillous inclusions, vacuolization of the cytoplasm, and electron-dense vesicles (Fig. 3C and Supplementary Fig. 3, http://links.lww.com/MPG/A362). No MYO5B mutations were found.
Patient 6 was born premature at 31 weeks of gestation (weight 1645 g) from Israeli nonconsanguineous parents. Diarrhea began later, at 14 months of life, characterized by significant steatorrhea (23 g/day when he was 11 years old, 7–14 g/day when he was 14 years old). Parenteral nutrition was started only when he was 3 years old (approximately 60 mL/kg, 6/7 days). He also experienced a neonatal hydrocephaly that was treated surgically. He had normal neurological development. At present, he is 24 years old. At his last visit, when he was 20 years old, he needed parenteral nutrition 4 days/week. He had normal growth.
The diagnosis of MVID was made when he was 4 years old. Standard histology showed mild villous atrophy. Some surface enterocytes were vacuolated and a mild inflammatory infiltrate within the lamina propria was noted. PAS staining showed a focal accumulation pattern in the crypt enterocytes. The last biopsy, when he was 19 years old, showed the same abnormalities (Fig. 1H and Supplementary Fig. 2A and B, http://links.lww.com/MPG/A361). At TEM examination, microvilli were rare and shortened. There were possible microvillous inclusions and lots of secretory granules. Two MYO5B mutations were found. The first one (c656G>A) was located on the sixth exon and was already described in a Turkish patient and the second one was located on the 31st exon (c4028T>C). The mutations affect the motor part and the rab binding domain of the protein.
Patients 7 and 8 are offsprings of French nonconsanguineous parents. Diarrhea began when they were 5 months old, insidiously, with high steatorrhea levels (between 7 and 12 g/day), but low sodium excretion (15 mmol/L for the girl). Parenteral nutrition was started at 8 months for the boy (patient 7) and at 18 months for his younger sister (patient 8). After a few months, it moved for enteral nutrition and then for normal feeding. At the beginning, gluten intolerance was suspected: gluten antibodies were negative for the boy, whereas antigliadin immunoglobulin G levels were elevated for the girl. The boy is now 28 years old and the girl is 11 years old.
For patient 7, until 4 years of age, duodenal biopsies showed total or subtotal villous atrophy with crypt hyperplasia and mild inflammatory infiltrate; however, when he was 18 years old, a duodenal biopsy revealed almost normal villi but a focal PAS-positive pattern, mostly on the apical pole of surface enterocytes. The number of intraepithelial lymphocytes was at the upper limit of normal. TEM showed rare microvilli abnormalities, some electron-dense vesicles, and a mild degree of cellular sickness. For patient 8, the diagnosis was made at 18 months. Focal accumulation of PAS-positive material at the luminal pole of surface and crypt enterocytes was seen. There was only a mild villous atrophy. Histological data improved at 4 years of age, with an almost normal villous relief but the persistence of the abnormal PAS-staining pattern (Fig. 1I and Supplementary Fig. 2C and D). TEM analyses were done earlier for patient 8, when she still had digestive symptoms, and revealed rarefied microvilli, possible microvillous inclusions and electron-dense vesicles (Fig. 3D). Genetic screening found the same 2 mutations in the 2 children. One in the 14th exon (C1347delC) led to a truncated protein. The other one, located on the 24th exon (c3163-3165dup), was also found in patient 1.
In summary, all 8 reported patients were characterized by a typical abnormal PAS staining on light microscopy, which made us discuss the diagnosis of MVID. All of them exhibited atypical clinical presentations, but 4 exhibited 1 or more TEM diagnostic hallmarks proposed by Davidson et al (4), including loss of microvilli, microvillus inclusions, and secretory granules. Finally, 6 patients, corresponding to 4 distinct pedigrees, were mutated for MYO5B.
Gestations were unremarkable, except for patient 3. In fact, only 4 cases from the literature had antenatal symptoms consisting of hydramnios or echogenic bowel. Among these 4 cases, 2 mothers had a strict follow-up because of health problems, whereas the third baby had a neuronal intestinal dysplasia with bowel dilatation (5–8). Antenatal echography therefore seems to have a limited role for prenatal diagnostic here and in the literature.
Three patients experienced malformations. All of them had dysmorphy and severe mental retardation. To our knowledge, there are only a few patients described in the literature with malformations (11–13), and none with sensory defects. Only 2 patients with no MYO5B mutations had the most severe malformations, suggesting another genetic cause of their disease. Three patients were small, with height values under −2 SD despite nutritional assistance and sometimes despite a treatment with growth hormone. These data suggest that in some cases MVID may be a component of a more complete syndrome.
In the reported cases, digestive symptoms were milder than in the classical presentation. Either they had a delayed starting date (patients 6, 7, and 8) or outputs were less considerable than in classic MVID. Parenteral nutrition could even be stopped in 3 patients. To our knowledge, these are the third and fourth spontaneous cures described to date (11,23).
Three patients had a cholestasis with low GGT levels whose evolution was fluctuant with medical treatment. One still had severe pruritus. In a previous study, cholestasis was described in 25% of the patients, before or even after isolated small bowel transplantation (15). It is known that myosin 5b is important for hepatocyte polarization (38). It is therefore possible that a dysfunction of myosin 5b leads to a defect of hepatocyte apical transporters (39).
All but 2 patients had MYO5B mutations. For the remaining 2 patients, the genetic defect remains to be identified. The exome sequencing strategy used here did not allow discarding genetic changes such as exon deletions or mutations within the MYO5B promotor region; however, immunohistochemical analyses of myosin 5b showed a normal signal, and thus did not argue for MYO5B gene abnormalities. For these patients, it should be more interesting to study alternative genes involved in the transport of apical proteins such as Rab8a, Rab11a, or FIP5. Because mutations in syntaxine 3 have been reported for 2 patients with MIVD, this gene should also be tested (40).
In patients with mutations, the functional impact of the mutations was not further examined with functional studies; however, among the mutations identified here, one was present in 2 families (patients 1, 7, and 8) and another one was already reported in a typical Turkish patient (31). More important, mutated patients carried 2 mutations as expected for a Mendelian recessive disorder. Thus, we conclude that patients’ mutations likely contribute to their histological and clinical findings.
MIVD is a rare pathology, with well-recognized clinical and histological aspects in its classic form. Most of the patients exhibit MYO5B mutations. This study suggests to extend the clinical spectrum of MVID to patients with less severe diarrhea and/or associated diseases.
The authors thank Alain Grodet for technical support.
1. Guarino A, Spagnuolo MI, Russo S, et al. Etiology and risk factors of severe and protracted diarrhea. J Pediatr Gastroenterol Nutr
2. Ventura A, Dragovich D. Intractable diarrhoea in infancy in the 1990s: a survey in Italy. Eur J Pediatr
3. Beck NS, Kang IS, Suh YL. Protracted diarrhea: results of the five-year survey in a tertiary hospital in Korea. J Korean Med Sci
4. Davidson GP, Cutz E, Hamilton JR, et al. Familial enteropathy: a syndrome of protracted diarrhea from birth, failure to thrive, and hypoplastic villus atrophy. Gastroenterology
5. Roggero P, Mazzola C, Fava G, et al. Intestinal microvillous atrophy
and transient neuronal dysplasia. Transplant Proc
6. Kennea N, Norbury R, Anderson G, et al. Congenital microvillous inclusion disease
presenting as antenatal bowel obstruction. Ultrasound Obstet Gynecol
7. Chen CP, Chiang MC, Wang TH, et al. Microvillus inclusion disease: prenatal ultrasound findings, molecular diagnosis and genetic counseling of congenital diarrhea. Taiwan J Obstet Gynecol
8. Levental M, Pretorius DH, Scioscia AL, et al. Prenatal detection of echogenic bowel in a fetus with familial microvillous atrophy
. J Ultrasound Med
9. Phillips AD, Schmitz J. Familial microvillous atrophy
: a clinicopathological survey of 23 cases. J Pediatr Gastroenterol Nutr
10. Ruemmele FM, Schmitz J, Goulet O. Microvillous inclusion disease
). Orphanet J Rare Dis
11. Martinez MA, Egea AS, Lopez JM, et al. Intestinal microvillous atrophy
in a patient with Down syndrome and aganglionic megacolon. Ultrastruct Pathol
12. Raafat F, Green NJ, Nathavitharana KA, et al. Intestinal microvillous dystrophy: a variant of microvillous inclusion disease
or a new entity? Hum Pathol
13. Gathungu GN, Pashankar DS, Sarita-Reyes CD, et al. Microvillus inclusion disease associated with coarctation of the aorta and bicuspid aortic valve. J Clin Gastroenterol
14. Loverdos I, GM, Lacaille F, et al. Severe intrahepatic cholestasis in microvillous inclusion disease
. J Pediatr Gastroenterol Nutr
2009; 48: (E23).
15. Halac U, Lacaille F, Joly F, et al. Microvillous inclusion disease
: how to improve the prognosis of a severe congenital enterocyte disorder. J Pediatr Gastroenterol Nutr
16. Heinz-Erian P, Schmidt H, Le Merrer M, et al. Congenital microvillus atrophy in a girl with autosomal dominant hypochondroplasia. J Pediatr Gastroenterol Nutr
17. Phillips AD, Jenkins P, Raafat F, et al. Congenital microvillous atrophy
: specific diagnostic features. Arch Dis Child
18. Walker-Smith JA, Phillips AD, Walford N, et al. Intravenous epidermal growth factor/urogastrone increases small-intestinal cell proliferation in congenital microvillous atrophy
19. Drumm B, Cutz E, Tomkins KB, et al. Urogastrone/epidermal growth factor in treatment of congenital microvillous atrophy
20. Pohl JF, Shub MD, Trevelline EE, et al. A cluster of microvillous inclusion disease
in the Navajo population. J Pediatr
21. Ruemmele FM, Jan D, Lacaille F, et al. New perspectives for children with microvillous inclusion disease
: early small bowel transplantation. Transplantation
22. Herzog D, Atkison P, Grant D, et al. Combined bowel-liver transplantation in an infant with microvillous inclusion disease
. J Pediatr Gastroenterol Nutr
23. Croft NM, Howatson AG, Ling SC, et al. Microvillous inclusion disease
: an evolving condition. J Pediatr Gastroenterol Nutr
24. Al-Daraji WI, Zelger B, Hussein MR. Microvillous inclusion disease
: a clinicopathologic study of 17 cases from the UK. Ultrastruct Pathol
25. Schofield DE, Agostini RM Jr, Yunis EJ. Gastrointestinal microvillus inclusion disease. Am J Clin Pathol
26. Groisman GM, Amar M, Livne E. CD10: a valuable tool for the light microscopic diagnosis of microvillous inclusion disease
(familial microvillous atrophy
). Am J Surg Pathol
27. Groisman GM, Ben-Izhak O, Schwersenz A, et al. The value of polyclonal carcinoembryonic antigen immunostaining in the diagnosis of microvillous inclusion disease
. Hum Pathol
28. Iancu TC, Mahajnah M, Manov I, et al. Microvillous inclusion disease
: ultrastructural variability. Ultrastruct Pathol
29. Phillips AD, Szafranski M, Man LY, et al. Periodic acid-Schiff staining abnormality in microvillous atrophy
: photometric and ultrastructural studies. J Pediatr Gastroenterol Nutr
30. Nathavitharana KA, Green NJ, Raafat F, et al. Siblings with microvillous inclusion disease
. Arch Dis Child
31. Müller T, Hess MW, Schiefermeier N, et al. MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity. Nat Genet
32. Ruemmele FM, Muller T, Schiefermeier N, et al. Loss-of-function of MYO5B is the main cause of microvillus inclusion disease: 15 novel mutations and a CaCo-2 RNAi cell model. Hum Mutat
33. Szperl AM, Golachowska MR, Bruinenberg M, et al. Functional characterization of mutations in the myosin Vb gene associated with microvillus inclusion disease. J Pediatr Gastroenterol Nutr
34. Erickson RP, Larson-Thome K, Valenzuela RK, et al. Navajo microvillous inclusion disease
is due to a mutation in MYO5B. Am J Med Genet A
35. Phillips A, Fransen J, Hauri HP, et al. The constitutive exocytotic pathway in microvillous atrophy
. J Pediatr Gastroenterol Nutr
36. Phillips AD, Brown A, Hicks S, et al. Acetylated sialic acid residues and blood group antigens localise within the epithelium in microvillous atrophy
indicating internal accumulation of the glycocalyx. Gut
37. Roland JT, Bryant DM, Datta A, et al. Rab GTPase-Myo5B complexes control membrane recycling and epithelial polarization. Proc Natl Acad Sci U S A
38. Wakabayashi Y, Dutt P, Lippincott-Schwartz J, et al. Rab11a and myosin Vb are required for bile canalicular formation in WIF-B9 cells. Proc Natl Acad Sci U S A
39. Girard M, Lacaille F, Verkarre V, et al. MYO5B and BSEP contribute to cholestatic liver disorder in microvillous inclusion disease
40. Wiegerinck CL, Janecke AR, Schneeberger K, et al. 1. Loss of syntaxin 3 causes variant microvillus inclusion disease. Gastroenterology
intractable diarrhea; microvillous atrophy; microvillous inclusion disease; myosin 5b
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