Neonatal Respiratory Dysfunction
Caused by SFTPC Gene Mutation: a Case Report and Literature Review
Weijie Yu, M.B.B.S., Qiuying Hou, M.B.B.S., Qinlai
Ying,
M.B.B.S., Wen Zhu*, M.B.B.S.
Pediatric department, the second affiliated hospital of Jiaxing medical
college, Jiaxing children’s medical center. Jiaxing city, Zhejiang
province. 314200, China.
* is the corresponding author.
Information of the corresponding author:
Mailing address: Pediatric department, the second affiliated hospital of
Jiaxing medical college, Jiaxing children’s medical center. Jiaxing
city, Zhejiang province. 314200, China.
Telephone number: 0573-8208093
Fax number: 0573-82080930
E-maill address: edgar281@sina.com
Abstract
Background: In this article, we present the case of a newborn with
respiratory insufficiency caused by SFTPC gene mutation. We summarized
and analyzed the clinical, chest imaging and gene test data of the case,
and reviewed related literature.
Case presentation: Case data: female infant, 6 hours with dyspnea.
Physical examination on admission showed three concave signs, no rales
or dryness in both lungs. Multiple chest radiographs indicated that the
brightness of the two lungs gradually decreased, and chest CT indicated
diffuse lung lesions. Sp-related gene detection indicated that SFTPC was
newly mutated due to c.563t > c (p.l188p). Literature
reported six similar cases: 1) SFTPC gene c.68G > G/A,
p.r23q heterozygosity missense mutation, 2) SFTPC gene c.115G
> G/T, p.v39l heterozygosity missense mutation, 3) c.203T
>a, p. Val68asp mutation, 4) c.435G> c
mutation, 5) Cys121Phe/C121F mutation, and 6) p. Cp121gly /C121G
mutation. All these cases developed severe neonatal respiratory distress
syndrome shortly after birth, and there are no reports consistent with
the gene loci and manifestations of this case.
Conclusion: The mutation of SFTPC gene can cause early respiratory
insufficiency and lead to progressive exacerbation of respiratory
failure. We report a newly mutated
SFTPC gene due to c.563t > c (p.l188p).
Keywords: SFTPC; genetic mutation; respiratory insufficiency
Introduction:
Genetic surfactant disorders often cause neonatal respiratory distress
syndromes.
Pulmonary surfactant could prevent the lung alveoli from collapsing
through reducing tension at the air-water interface. It consists of
proteins and lipids. Half of proteins consist of four SPs, namely SP-A,
SP-B, SP-C, and SP-D [1]. ABCA3, NKX2-1, GM-CSF
are also involved in the process of surfactant generation and secretion.
However, genetic variations are more frequently described in SFTPC and
ABCA3, and less frequently in NKX2-1, SFTPB, SFTPA, and GM-CSF[2]. In this article, we present a case of the
process of clinical diagnosis and treatment of a newborn with
respiratory insufficiency caused by SFTPC gene mutation. The newborn
developed aggravating symptoms. Chest imaging indicated diffuse lesions
in both lungs. Sp-related gene detection indicated a novel mutation of
SFTPC, which was newly mutated due to c.563t > c (p.l188p).
Case History:
Case summary:
The newborn was female, G3P2, gestational age was 38 weeks + 6 days. She
was delivered by caesarean section due to ”scarred uterus”, birth weight
was 3450g.The amniotic fluid was clear, umbilical cord and placenta were
normal. Apgar score at 1 and 5 minutes were 8 and 9 points respectively.
Half an hour after birth, she presented with shortness of breath and
grunting. Thereafter, she was observed on oxygen for 6 hours. Without
relief, she was transferred to our hospital.
Family history:
The parents were in good health and denied consanguineous marriages.
There was no family history of hereditary diseases. The couple has a
7-year-old daughter without similar history.
Physical examination:
T: 37.5℃, P: 110 beats/min, R: 42 beats/min, conscious, slightly
shortness of breath, moaning, the response cries were fine. The bregma
was flat, 0.5x0.5cm in size. Neck was soft. In both lungs, respiratory
sounds were coarse, a small amount of coarse wet rumbling was heard.
Heart rhythms and heart sounds were normal, no murmurs heard. The
abdomen was flat and soft, the liver was detected at 1.0cm below the
ribs, 1.5cm below the xiphoid process, the splenic was not palpable, no
mass was detected. The bowel sounds were present. Umbilical cord
ligation was intact, and there was no exudate. Limb activity was less
than expected, muscle tone was normal, limbs were cool.CRT was 3
seconds.
Auxiliary examination:
On admission, blood glucose was 3.9 mmol/L, transcutaneous oxygen
saturation was 100% (under nasal oxygen).
Lab tests:
On Jan 1st, neonatal blood gas : PH was 7.34, partial pressure of carbon
dioxide was 38.6 mmHg, partial pressure of oxygen was 145.4 mmHg,
concentration of HCO3 was 20.4 mmol/L, residual base was
-4.87 mmol/L, oxygen saturation was 100.0%, lactate was 1.90 mmol/L.
Pediatric routine blood test and hCRP test at emergency: white blood
cell count was 32.64*109/L, ultra-sensitive C-reactive
protein level was 3.58mg/L, percentage of neutrophil was 93.3%,
hemoglobin was 179g/L, platelet count was 253*109/L.
Emergency PCT: calcitonin level was 10.02ng/ml. On Jan 3rd ,neonatal
blood gas : pH was 7.38, partial pressure of carbon dioxide was 36.9
mmHg, partial pressure of oxygen was 32.9mmHg, concentration of
HCO3 was 21.4 mmol/L, residual base was -3.05 mmol/L,
oxygen saturation was 75.1%, lactic acid was 3.2mmol/L, reduced
hemoglobin was 24.3%; On Jan 4th , neonatal blood gas : pH was 7.29,
partial pressure of carbon dioxide was 53.4 mmHg, partial pressure of
oxygen was 41.4 mmHg, concentration of HCO3 was 25
mmol/L, residual base was -2.48 mmol/L, oxygen saturation was 80.4%,
glucose was 6.3mmol/L, lactic acid was 2.9mmol/L, reduced hemoglobin was
19.2%; On Jan 6th , neonatal blood gas : PH was 7.36, partial pressure
of carbon dioxide was 62.2 mmHg, partial pressure of oxygen was 46.0
mmHg, concentration of HCO3 was 34.2 mmol/L, residual
base was 6.65mmol/L, oxygen saturation was 85.7%, reduced hemoglobin
was 14.0%, lactate was 1.1 mmol/L. On Jan 7th , neonatal blood gas : PH
was 7.37, partial pressure of carbon dioxide was 57.8 mmHg, partial
pressure of oxygen was 75.1 mmHg, concentration of oxygen was 32.8
mmol/L, standard bicarbonate concentration was 28.8 mmol/L, total oxygen
content was 75.1 mmol/L, total carbon dioxide was 29.0mmol/L, residual
base was 5.81mmol/L, oxygen saturation was 97.9%, reduced hemoglobin
was 14.0%, lactic acid was 1.5 mmol/L.
Imaging:
On Jan 1st, chest and abdomen x-ray illustrated that she had bronchitis.
On Jan 4th, chest x-ray indicated that she had bronchiectasis.
Gene test:
Sp-related gene detection showed that SFTPC was newly mutated due to
c.563t > c (p.l188p).
Treatment history:
After admission, the patient was placed in a warm box with nasal
catheter oxygenation, then given cefotaxime injection and penicillin G
sodium injection for anti-infection, given rehydration and other
treatment to combat symptoms. On the third day after admission, under
nasal catheter oxygenation (0.5L/min), there were repeated paroxysmal
drop in oxygen saturation, which dropped to 60%-70% and could
gradually rise again. On the fourth day, the paroxysmal drop was more
frequent, and oxygen saturation dropped to 30%-70%, then slowly rose
on its own. There was no convulsion, no breath-holding, no apnea, no
fever. She could drink milk. Physical examination showed that she had a
concave sign, the cry was still loud, the response was normal. Morning
TCB result: 3.9/3.4mg/dl. The respiratory sounds of both lungs were
coarse, but no obvious rumbling was heard. Heart rhythm was normal,
heart sounds were moderate, no murmur was heard. The abdomen was flat
and soft, the liver was 1.0cm below the rib, 1.5cm below the
xiphoid
process, the splenic was not palpable, the bowel sounds were present,
the limbs were less active, the extremities were warm. CRT was 3
seconds. On the eighth day, high-flow oxygen (Jan 8th-Jan 11th) and
nebulization (Jan 8th-Jan 11th) were given, because of carbon dioxide
retention in the follow-up blood gas analysis and low permeability of
both lungs in chest radiograph, then changed to high-frequency assisted
ventilation (Jan 11th to Jan 18th). On Jan 11th, 240 mg of Curosurf was
given as intra-tracheal drip, and then high-frequency assisted
ventilation (Jan 18th -Jan 19th) was changed to normal-frequency
assisted ventilation (Jan 19th-Jan 20th), because of positive
inspiratory cavity, then changed to high-flow oxygen administration (Jan
20th-Feb 5th); On Jan 18th,chest CT suggested there were diffuse lung
lesions, then underwent WES examination and bronchoscopic alveolar
lavage. On Feb 2nd, follow-up chest radiograph showed that her lung
transmittance decreased, again she was given Curosurf 480mg + Pulmicort
1mg via intra-tracheal drip. Dyspnea was improved for a while, then
dyspnea worsened progressively. On Feb 5th, tracheal intubation was
given, high-frequency ventilator-assisted ventilation was given until
Feb 8th. The ventilator parameters gradually increased. Considering it
was difficult to recover from the disease, the family gave up further
treatments, then the patient died.
The chest radiograph gradually decreased in translucency as the disease
progressed (Figure 1, Figure 2, Figure 3).
Discussion
Neonatal respiratory distress syndrome (NRDS) is one of the most common
critical illnesses in the neonatal period, most often seen in premature
infants, mainly due to small gestational age and inadequate production
of surface active substances covering lungs. However, it could also be
seen in full-term or near-full-term infants. The condition is often
severe and is a common cause of neonatal death. NRDS is often treated
with supplementation of lung surface active substances, sometimes the
efficacy is not satisfying. The main components of pulmonary surfactant
are SP and phospholipids, and SP contains four subtypes: SP-A, SP-B,
SP-C and SP-D. Among them, SP-C is closely related to the development of
respiratory distress syndrome (RDS) [3]. The
activity and function of pulmonary surfactant are closely related to the
concentration and activity of SP-C [4].The SP-C
gene is 3.5-kb and it contains six exons, located on the short arm of
chromosome 8, which can selectively promote the synthesis of dipalmitoyl
lecithin and phospholipid. It assists in the distribution of pulmonary
surfactant on the alveolar surface and maintains its stability, reduces
alveolar surface tension [4]. Alteration in the
SP-C allele are closely related with NRDS. The mechanism is associated
with the accumulation of misfolded SP-C precursor proteins. The
misfolding could lead to protein aggregation and endoplasmic reticulum
stress. Then cause pro-inflammatory cytokines releasing and lead to
apoptosis [5-6].
Genetic defects in surface active substance metabolism are related with
a wide range of clinical manifestations [7]. Early
treatment may improve symptoms, but diagnosis is often delayed due to
phenotypic and genotypic variants. This case is a heterozygous variant
of the SFTPC gene NM-003018: exon5: c.563T>C (p.L188P). The
causative variant of SFTPC gene can cause pulmonary surfactant
metabolism dysfunction type II; it is associated with progressive
respiratory insufficiency and pulmonary disease, in which excessive
lipoprotein accumulation in the alveoli causes severe respiratory
distress. The main clinical features are neonatal respiratory
insufficiency, alveolar protein deposition disease, and interstitial
pneumonia. SFTPC mutations are caused by de novo mutations, they are
autosomal dominant disorders and cases are mostly disseminated[8]. Various types of SP-C gene mutations have
been reported in the literature, with the exon 5 region being the most
common mutation hotspot [9]. The pathogenesis of
SFTPC mutation is the misfolding and abnormal processing of the SP-C
precursor protein, which leads to cell damage and apoptosis, causing
abnormal intracellular directional transport of SP-C protein and
accumulation in alveolar type II cells [10-13].
Chronic alveolar inflammation is associated with interstitial lung
disease in older children and adults [14]. Park et
al reported the first case in Korea, a child who suffered neonatal RDS
and developed childhood interstitial lung disease due to a novel
heterozygous SFTPC mutation: c.203T>A[15].Alzaid et al reported the first case in Arab
world, with mutation of c.218T>C[16].
Mutations in different sites of SFTPC cause variable clinical
manifestations and transitions of associated lung disease, ranging from
neonatal respiratory insufficiency, fatal neonatal respiratory distress
syndrome, respiratory failure in infancy, interstitial lung disease in
childhood, alveolar protein deposition, to chronic interstitial lung
disease in adults. Children with mild disease gradually develop
hypoxemia and dyspnea, and children with severe disease often die within
3 to 6 months, surviving children often need mechanical ventilation and
long-term oxygen therapy, consistent with van Hoorn Jeroen[17] and other reports. SFTPC mutations cause
related pulmonary symptoms and treatment difficulties. Literature
reported a case of SFTPC gene in exon 4 coding for Cys121Gly/C121G,
experimental treatment with hydroxychloroquine has resulted in
significant clinical improvement within 2 weeks[18]. A case of successful lung transplantation
has also been reported [19]. Early detection and
diagnosis are relatively difficult in patients with early symptoms, and
chest X-rays are not evident, high-resolution tomography (HRCT) scan
features can help in early identification [20-21].
In summary, when neonates show signs of respiratory insufficiency such
as repeated decreases in oxygen saturation after birth, especially in
full-term infants, after excluding congenital heart disease, it is
recommended to improve lung surface active substance-related gene
testing. Early chest high-resolution CT examination can clarify the
diagnosis and subsequent treatments could improve symptoms at an early
stage.
Conclusion:
We reported a case with c.563t > c (p.l188p) mutation of
SFTPC gene. It can cause early respiratory insufficiency and eventually
lead to progressive exacerbation of respiratory failure.
Declarations:
Ethics approval and consent to participate: The study was approved by
Medical Ethics Committee of The Second Hospital of Jiaxing (Approval
code: 20200522H03).
Availability of data and materials: Data sharing is not applicable to
this article as no datasets were generated or analysed during the
current study.
Competing interests: None declared.
Funding: Not applicable.
Acknowledgements: Not applicable.
Authors’ contributions: Weijie Yu, Qiuying Hou, Qinlai Ying were
responsible for the treatment of this patient, under the supervision of
Yufeng Zhang and Wen Zhu. Weijie, Qiuying Hou did the literature review
and drafted the manuscript.
List of abbreviation: CT: computated tomography, T: temperature, P:
pulse, R: respiratory rate, CRT: clot retraction test,
HCO3: bicarbonate, TCB: total conjugated bilirubin.
References:
Akella A,Deshpande SB. Pulmonary surfactants and their role in
pathophysiology of lung disorders[J].Indian J Exp
Biol,2013,51(1):5—22.
Glasser R,Mallampalli K. Surfactant and its role in the pathobiology of
pulmonary infection.[J] .Microbes Infect., 2012, 14: 17-25.
Sweet G, Carnielli V, Greisen G et al. European Consensus Guidelines on
the Management of Respiratory Distress Syndrome - 2019 Update.[J]
.Neonatology, 2019, 115: 432-450.
Jiang M,Roth G,Chun-On P et al. SFTPC Phenotypic Diversity Caused by
Differential Expression of -Cre-Transgenic Alleles.[J] .Am. J.
Respir. Cell Mol. Biol., 2020, 62: 692-698.
Almlén A,Walther J,Waring J et al. Synthetic surfactant based on
analogues of SP-B and SP-C is superior to single-peptide surfactants in
ventilated premature rabbits.[J] .Neonatology, 2010, 98: 91-9.
Nathan N, Borensztajn K, Clement A. Genetic causes and clinical
management of pediatric interstitial lung diseases.[J] .Curr Opin
Pulm Med, 2018, 24: 253-259.
Delestrain C, Simon S ,Aissat A et al. Deciphering the mechanism of
Q145H SFTPC mutation unmasks a splicing defect and explains the severity
of the phenotype.[J] .Eur. J. Hum. Genet., 2017, 25: 779-782.
Da H,Yuanyuan Q,Huijun W et al. Surfactant protein C gene mutations in
two newborns with neonatal respiratory distress syndrome and literature
review[J]. Chinese Journal of Evidence -Based Pediatric, 2016,
11(1): 51-55.
Chen J H,Zhao D Y,An S H et al. [Clinical manifestations of three
cases of surfactant protein C p. V39L mutation].[J] .Zhonghua Er
Ke Za Zhi, 2017, 55: 457-461.
Liu T,Sano K ,Ogiwara N et al. A novel surfactant protein C L55F
mutation associated with interstitial lung disease alters subcellular
localization of proSP-C in A549 cells.[J] .Pediatr. Res., 2016, 79:
27-33.
Hawkins A,Guttentag H,Deterding R et al. A non-BRICHOS SFTPC mutant
(SP-CI73T) linked to interstitial lung disease promotes a late block in
macroautophagy disrupting cellular proteostasis and mitophagy.[J]
.Am. J. Physiol. Lung Cell Mol. Physiol., 2015, 308: L33-47.
Katzen J,Wagner D,Venosa A et al. An SFTPC BRICHOS mutant links
epithelial ER stress and spontaneous lung fibrosis.[J] .JCI Insight,
2019, 4: undefined.
Hong D , Qi Y , Liu J , et al. A novel surfactant protein C mutation
resulting in aberrant protein processing and altered subcellular
localization causes infantile interstitial lung disease[J].
Pediatric Research.
Avital A,Hevroni A,Godfrey S et al. Natural history of five children
with surfactant protein C mutations and interstitial lung
disease.[J] .Pediatr. Pulmonol., 2014, 49: 1097-105.
Park S,Choi J,Kim T et al. SFTPC Pediatric Case Report on an
Interstitial Lung Disease with a Novel Mutation of Successfully Treated
with Lung Transplantation.[J] .J. Korean Med. Sci., 2018, 33: e159.
Alzaid A,Eltahir S,Amin M et al. SFTPC An gene mutation causes childhood
interstitial lung disease: first report in the Arab region.[J] .JRSM
Open, 2020, 11: 2054270419894821.
van Hoorn J,Brouwers A,Griese M et al. Successful weaning from
mechanical ventilation in a patient with surfactant protein C deficiency
presenting with severe neonatal respiratory distress.[J] .BMJ Case
Rep, 2014, 2014: undefined.
Hepping N,Griese M,Lohse P et al. Successful treatment of neonatal
respiratory failure caused by a novel surfactant protein C p.Cys121Gly
mutation with hydroxychloroquine.[J] .J Perinatol, 2013, 33: 492-4.
Park S,Choi J,Kim T et al. SFTPCPediatric Case Report on an Interstitial
Lung Disease with a Novel Mutation of Successfully Treated with Lung
Transplantation.[J] .J. Korean Med. Sci., 2018, 33: e159.
Mechri M,Epaud R,Emond S et al. Surfactant protein C gene (SFTPC)
mutation-associated lung disease: high-resolution computed tomography
(HRCT) findings and its relation to histological analysis.[J]
.Pediatr Pulmonol, 2010, 45: 1021-9.
Owen S,Manley J,Davis G et al. The evolution of modern respiratory care
for preterm infants.[J] .Lancet, 2017, 389: 1649-1659.